Merge remote-tracking branch 'origin' into divs

.github/workflows/publish_collab_image.yml

@@ -22,6 +22,9 @@ jobs:
       - name: Sign into DigitalOcean docker registry
         run: doctl registry login
 
+      - name: Prune Docker system
+        run: docker system prune
+
       - name: Checkout repo
         uses: actions/checkout@v3
         with:

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     "crates/auto_update",
     "crates/breadcrumbs",
     "crates/call",
+    "crates/channel",
     "crates/cli",
     "crates/client",
     "crates/clock",
@@ -13,6 +14,7 @@ members = [
     "crates/collab_ui",
     "crates/collections",
     "crates/command_palette",
+    "crates/component_test",
     "crates/context_menu",
     "crates/copilot",
     "crates/copilot_button",
@@ -60,7 +62,7 @@ members = [
     "crates/snippet",
     "crates/sqlez",
     "crates/sqlez_macros",
-    "crates/staff_mode",
+    "crates/feature_flags",
     "crates/sum_tree",
     "crates/terminal",
     "crates/text",
@@ -95,10 +97,11 @@ log = { version = "0.4.16", features = ["kv_unstable_serde"] }
 ordered-float = { version = "2.1.1" }
 parking_lot = { version = "0.11.1" }
 postage = { version = "0.5", features = ["futures-traits"] }
+prost = { version = "0.8" }
 rand = { version = "0.8.5" }
 refineable = { path = "./crates/refineable" }
 regex = { version = "1.5" }
-rust-embed = { version = "6.3", features = ["include-exclude"] }
+rust-embed = { version = "8.0", features = ["include-exclude"] }
 schemars = { version = "0.8" }
 serde = { version = "1.0", features = ["derive", "rc"] }
 serde_derive = { version = "1.0", features = ["deserialize_in_place"] }

Dockerfile

@@ -1,6 +1,6 @@
 # syntax = docker/dockerfile:1.2
 
-FROM rust:1.71-bullseye as builder
+FROM rust:1.72-bullseye as builder
 WORKDIR app
 COPY . .
 

assets/keymaps/default.json

@@ -521,7 +521,8 @@
       "ctrl-alt-cmd-f": "workspace::FollowNextCollaborator",
       // TODO: Move this to a dock open action
       "cmd-shift-c": "collab_panel::ToggleFocus",
-      "cmd-alt-i": "zed::DebugElements"
+      "cmd-alt-i": "zed::DebugElements",
+      "ctrl-shift-:": "editor::ToggleInlayHints",
     }
   },
   {

assets/keymaps/vim.json

@@ -137,10 +137,67 @@
           "partialWord": true
         }
       ],
+      "g j": [
+        "vim::Down",
+        {
+          "displayLines": true
+        }
+      ],
+      "g down": [
+        "vim::Down",
+        {
+          "displayLines": true
+        }
+      ],
+      "g k": [
+        "vim::Up",
+        {
+          "displayLines": true
+        }
+      ],
+      "g up": [
+        "vim::Up",
+        {
+          "displayLines": true
+        }
+      ],
+      "g $": [
+        "vim::EndOfLine",
+        {
+          "displayLines": true
+        }
+      ],
+      "g end": [
+        "vim::EndOfLine",
+        {
+          "displayLines": true
+        }
+      ],
+      "g 0": [
+        "vim::StartOfLine",
+        {
+          "displayLines": true
+        }
+      ],
+      "g home": [
+        "vim::StartOfLine",
+        {
+          "displayLines": true
+        }
+      ],
+      "g ^": [
+        "vim::FirstNonWhitespace",
+        {
+          "displayLines": true
+        }
+      ],
       // z commands
       "z t": "editor::ScrollCursorTop",
       "z z": "editor::ScrollCursorCenter",
       "z b": "editor::ScrollCursorBottom",
+      "z c": "editor::Fold",
+      "z o": "editor::UnfoldLines",
+      "z f": "editor::FoldSelectedRanges",
       // Count support
       "1": [
         "vim::Number",

assets/settings/default.json

@@ -98,6 +98,7 @@
     // Whether to show selections in the scrollbar.
     "selections": true
   },
+  "relative_line_numbers": false,
   // Inlay hint related settings
   "inlay_hints": {
     // Global switch to toggle hints on and off, switched off by default.
@@ -284,8 +285,6 @@
     //          "directory": "~/zed/projects/"
     //        }
     //      }
-    //
-    //
     "working_directory": "current_project_directory",
     // Set the cursor blinking behavior in the terminal.
     // May take 4 values:
@@ -334,13 +333,32 @@
     //         "line_height": {
     //           "custom": 2
     //         },
-    "line_height": "comfortable"
+    "line_height": "comfortable",
+    // Activate the python virtual environment, if one is found, in the
+    // terminal's working directory (as resolved by the working_directory
+    // setting). Set this to "off" to disable this behavior.
+    "detect_venv": {
+      "on": {
+        // Default directories to search for virtual environments, relative
+        // to the current working directory. We recommend overriding this
+        // in your project's settings, rather than globally.
+        "directories": [
+          ".env",
+          "env",
+          ".venv",
+          "venv"
+        ],
+        // Can also be 'csh' and 'fish'
+        "activate_script": "default"
+      }
+    }
     // Set the terminal's font size. If this option is not included,
     // the terminal will default to matching the buffer's font size.
-    // "font_size": "15"
+    // "font_size": "15",
     // Set the terminal's font family. If this option is not included,
     // the terminal will default to matching the buffer's font family.
-    // "font_family": "Zed Mono"
+    // "font_family": "Zed Mono",
+    // ---
   },
   // Difference settings for semantic_index
   "semantic_index": {

crates/ai/src/assistant.rs

@@ -855,14 +855,14 @@ impl Conversation {
     ) -> Self {
         let markdown = language_registry.language_for_name("Markdown");
         let buffer = cx.add_model(|cx| {
-            let mut buffer = Buffer::new(0, "", cx);
+            let mut buffer = Buffer::new(0, cx.model_id() as u64, "");
             buffer.set_language_registry(language_registry);
             cx.spawn_weak(|buffer, mut cx| async move {
                 let markdown = markdown.await?;
                 let buffer = buffer
                     .upgrade(&cx)
                     .ok_or_else(|| anyhow!("buffer was dropped"))?;
-                buffer.update(&mut cx, |buffer, cx| {
+                buffer.update(&mut cx, |buffer: &mut Buffer, cx| {
                     buffer.set_language(Some(markdown), cx)
                 });
                 anyhow::Ok(())
@@ -944,7 +944,7 @@ impl Conversation {
         let mut message_anchors = Vec::new();
         let mut next_message_id = MessageId(0);
         let buffer = cx.add_model(|cx| {
-            let mut buffer = Buffer::new(0, saved_conversation.text, cx);
+            let mut buffer = Buffer::new(0, cx.model_id() as u64, saved_conversation.text);
             for message in saved_conversation.messages {
                 message_anchors.push(MessageAnchor {
                     id: message.id,
@@ -958,7 +958,7 @@ impl Conversation {
                 let buffer = buffer
                     .upgrade(&cx)
                     .ok_or_else(|| anyhow!("buffer was dropped"))?;
-                buffer.update(&mut cx, |buffer, cx| {
+                buffer.update(&mut cx, |buffer: &mut Buffer, cx| {
                     buffer.set_language(Some(markdown), cx)
                 });
                 anyhow::Ok(())
@@ -1128,7 +1128,9 @@ impl Conversation {
                     stream: true,
                 };
 
-                let Some(api_key) = self.api_key.borrow().clone() else { continue };
+                let Some(api_key) = self.api_key.borrow().clone() else {
+                    continue;
+                };
                 let stream = stream_completion(api_key, cx.background().clone(), request);
                 let assistant_message = self
                     .insert_message_after(
@@ -1484,7 +1486,9 @@ impl Conversation {
             }) {
                 current_message = messages.next();
             }
-            let Some(message) = current_message.as_ref() else { break };
+            let Some(message) = current_message.as_ref() else {
+                break;
+            };
 
             // Skip offsets that are in the same message.
             while offsets.peek().map_or(false, |offset| {
@@ -1921,7 +1925,10 @@ impl ConversationEditor {
         let Some(panel) = workspace.panel::<AssistantPanel>(cx) else {
             return;
         };
-        let Some(editor) = workspace.active_item(cx).and_then(|item| item.act_as::<Editor>(cx)) else {
+        let Some(editor) = workspace
+            .active_item(cx)
+            .and_then(|item| item.act_as::<Editor>(cx))
+        else {
             return;
         };
 

crates/call/Cargo.toml

@@ -20,6 +20,7 @@ test-support = [
 
 [dependencies]
 audio = { path = "../audio" }
+channel = { path = "../channel" }
 client = { path = "../client" }
 collections = { path = "../collections" }
 gpui = { path = "../gpui" }

crates/call/src/call.rs

@@ -7,9 +7,8 @@ use std::sync::Arc;
 use anyhow::{anyhow, Result};
 use audio::Audio;
 use call_settings::CallSettings;
-use client::{
-    proto, ChannelId, ClickhouseEvent, Client, TelemetrySettings, TypedEnvelope, User, UserStore,
-};
+use channel::ChannelId;
+use client::{proto, ClickhouseEvent, Client, TelemetrySettings, TypedEnvelope, User, UserStore};
 use collections::HashSet;
 use futures::{future::Shared, FutureExt};
 use postage::watch;

crates/call/src/room.rs

@@ -644,7 +644,9 @@ impl Room {
 
                 if let Some(participants) = remote_participants.log_err() {
                     for (participant, user) in room.participants.into_iter().zip(participants) {
-                        let Some(peer_id) = participant.peer_id else { continue };
+                        let Some(peer_id) = participant.peer_id else {
+                            continue;
+                        };
                         this.participant_user_ids.insert(participant.user_id);
 
                         let old_projects = this

crates/channel/Cargo.toml

@@ -0,0 +1,51 @@
+[package]
+name = "channel"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[lib]
+path = "src/channel.rs"
+doctest = false
+
+[features]
+test-support = ["collections/test-support", "gpui/test-support", "rpc/test-support"]
+
+[dependencies]
+client = { path = "../client" }
+collections = { path = "../collections" }
+db = { path = "../db" }
+gpui = { path = "../gpui" }
+util = { path = "../util" }
+rpc = { path = "../rpc" }
+text = { path = "../text" }
+language = { path = "../language" }
+settings = { path = "../settings" }
+feature_flags = { path = "../feature_flags" }
+sum_tree = { path = "../sum_tree" }
+
+anyhow.workspace = true
+futures.workspace = true
+image = "0.23"
+lazy_static.workspace = true
+log.workspace = true
+parking_lot.workspace = true
+postage.workspace = true
+rand.workspace = true
+schemars.workspace = true
+smol.workspace = true
+thiserror.workspace = true
+time.workspace = true
+tiny_http = "0.8"
+uuid = { version = "1.1.2", features = ["v4"] }
+url = "2.2"
+serde.workspace = true
+serde_derive.workspace = true
+tempfile = "3"
+
+[dev-dependencies]
+collections = { path = "../collections", features = ["test-support"] }
+gpui = { path = "../gpui", features = ["test-support"] }
+rpc = { path = "../rpc", features = ["test-support"] }
+settings = { path = "../settings", features = ["test-support"] }
+util = { path = "../util", features = ["test-support"] }

crates/channel/src/channel.rs

@@ -0,0 +1,14 @@
+mod channel_store;
+
+pub mod channel_buffer;
+use std::sync::Arc;
+
+pub use channel_store::*;
+use client::Client;
+
+#[cfg(test)]
+mod channel_store_tests;
+
+pub fn init(client: &Arc<Client>) {
+    channel_buffer::init(client);
+}

crates/channel/src/channel_buffer.rs

@@ -0,0 +1,197 @@
+use crate::Channel;
+use anyhow::Result;
+use client::Client;
+use gpui::{AppContext, AsyncAppContext, Entity, ModelContext, ModelHandle};
+use rpc::{proto, TypedEnvelope};
+use std::sync::Arc;
+use util::ResultExt;
+
+pub(crate) fn init(client: &Arc<Client>) {
+    client.add_model_message_handler(ChannelBuffer::handle_update_channel_buffer);
+    client.add_model_message_handler(ChannelBuffer::handle_add_channel_buffer_collaborator);
+    client.add_model_message_handler(ChannelBuffer::handle_remove_channel_buffer_collaborator);
+}
+
+pub struct ChannelBuffer {
+    pub(crate) channel: Arc<Channel>,
+    connected: bool,
+    collaborators: Vec<proto::Collaborator>,
+    buffer: ModelHandle<language::Buffer>,
+    client: Arc<Client>,
+    subscription: Option<client::Subscription>,
+}
+
+pub enum Event {
+    CollaboratorsChanged,
+    Disconnected,
+}
+
+impl Entity for ChannelBuffer {
+    type Event = Event;
+
+    fn release(&mut self, _: &mut AppContext) {
+        if self.connected {
+            self.client
+                .send(proto::LeaveChannelBuffer {
+                    channel_id: self.channel.id,
+                })
+                .log_err();
+        }
+    }
+}
+
+impl ChannelBuffer {
+    pub(crate) async fn new(
+        channel: Arc<Channel>,
+        client: Arc<Client>,
+        mut cx: AsyncAppContext,
+    ) -> Result<ModelHandle<Self>> {
+        let response = client
+            .request(proto::JoinChannelBuffer {
+                channel_id: channel.id,
+            })
+            .await?;
+
+        let base_text = response.base_text;
+        let operations = response
+            .operations
+            .into_iter()
+            .map(language::proto::deserialize_operation)
+            .collect::<Result<Vec<_>, _>>()?;
+
+        let collaborators = response.collaborators;
+
+        let buffer = cx.add_model(|_| {
+            language::Buffer::remote(response.buffer_id, response.replica_id as u16, base_text)
+        });
+        buffer.update(&mut cx, |buffer, cx| buffer.apply_ops(operations, cx))?;
+
+        let subscription = client.subscribe_to_entity(channel.id)?;
+
+        anyhow::Ok(cx.add_model(|cx| {
+            cx.subscribe(&buffer, Self::on_buffer_update).detach();
+
+            Self {
+                buffer,
+                client,
+                connected: true,
+                collaborators,
+                channel,
+                subscription: Some(subscription.set_model(&cx.handle(), &mut cx.to_async())),
+            }
+        }))
+    }
+
+    async fn handle_update_channel_buffer(
+        this: ModelHandle<Self>,
+        update_channel_buffer: TypedEnvelope<proto::UpdateChannelBuffer>,
+        _: Arc<Client>,
+        mut cx: AsyncAppContext,
+    ) -> Result<()> {
+        let ops = update_channel_buffer
+            .payload
+            .operations
+            .into_iter()
+            .map(language::proto::deserialize_operation)
+            .collect::<Result<Vec<_>, _>>()?;
+
+        this.update(&mut cx, |this, cx| {
+            cx.notify();
+            this.buffer
+                .update(cx, |buffer, cx| buffer.apply_ops(ops, cx))
+        })?;
+
+        Ok(())
+    }
+
+    async fn handle_add_channel_buffer_collaborator(
+        this: ModelHandle<Self>,
+        envelope: TypedEnvelope<proto::AddChannelBufferCollaborator>,
+        _: Arc<Client>,
+        mut cx: AsyncAppContext,
+    ) -> Result<()> {
+        let collaborator = envelope.payload.collaborator.ok_or_else(|| {
+            anyhow::anyhow!(
+                "Should have gotten a collaborator in the AddChannelBufferCollaborator message"
+            )
+        })?;
+
+        this.update(&mut cx, |this, cx| {
+            this.collaborators.push(collaborator);
+            cx.emit(Event::CollaboratorsChanged);
+            cx.notify();
+        });
+
+        Ok(())
+    }
+
+    async fn handle_remove_channel_buffer_collaborator(
+        this: ModelHandle<Self>,
+        message: TypedEnvelope<proto::RemoveChannelBufferCollaborator>,
+        _: Arc<Client>,
+        mut cx: AsyncAppContext,
+    ) -> Result<()> {
+        this.update(&mut cx, |this, cx| {
+            this.collaborators.retain(|collaborator| {
+                if collaborator.peer_id == message.payload.peer_id {
+                    this.buffer.update(cx, |buffer, cx| {
+                        buffer.remove_peer(collaborator.replica_id as u16, cx)
+                    });
+                    false
+                } else {
+                    true
+                }
+            });
+            cx.emit(Event::CollaboratorsChanged);
+            cx.notify();
+        });
+
+        Ok(())
+    }
+
+    fn on_buffer_update(
+        &mut self,
+        _: ModelHandle<language::Buffer>,
+        event: &language::Event,
+        _: &mut ModelContext<Self>,
+    ) {
+        if let language::Event::Operation(operation) = event {
+            let operation = language::proto::serialize_operation(operation);
+            self.client
+                .send(proto::UpdateChannelBuffer {
+                    channel_id: self.channel.id,
+                    operations: vec![operation],
+                })
+                .log_err();
+        }
+    }
+
+    pub fn buffer(&self) -> ModelHandle<language::Buffer> {
+        self.buffer.clone()
+    }
+
+    pub fn collaborators(&self) -> &[proto::Collaborator] {
+        &self.collaborators
+    }
+
+    pub fn channel(&self) -> Arc<Channel> {
+        self.channel.clone()
+    }
+
+    pub(crate) fn disconnect(&mut self, cx: &mut ModelContext<Self>) {
+        if self.connected {
+            self.connected = false;
+            self.subscription.take();
+            cx.emit(Event::Disconnected);
+            cx.notify()
+        }
+    }
+
+    pub fn is_connected(&self) -> bool {
+        self.connected
+    }
+
+    pub fn replica_id(&self, cx: &AppContext) -> u16 {
+        self.buffer.read(cx).replica_id()
+    }
+}

crates/channel/src/channel_store.rs

@@ -1,19 +1,14 @@
-use crate::Status;
-use crate::{Client, Subscription, User, UserStore};
-use anyhow::anyhow;
-use anyhow::Result;
-use collections::HashMap;
-use collections::HashSet;
-use futures::channel::mpsc;
-use futures::Future;
-use futures::StreamExt;
-use gpui::{AsyncAppContext, Entity, ModelContext, ModelHandle, Task};
+use crate::channel_buffer::ChannelBuffer;
+use anyhow::{anyhow, Result};
+use client::{Client, Status, Subscription, User, UserId, UserStore};
+use collections::{hash_map, HashMap, HashSet};
+use futures::{channel::mpsc, future::Shared, Future, FutureExt, StreamExt};
+use gpui::{AsyncAppContext, Entity, ModelContext, ModelHandle, Task, WeakModelHandle};
 use rpc::{proto, TypedEnvelope};
 use std::sync::Arc;
 use util::ResultExt;
 
 pub type ChannelId = u64;
-pub type UserId = u64;
 
 pub struct ChannelStore {
     channels_by_id: HashMap<ChannelId, Arc<Channel>>,
@@ -23,6 +18,7 @@ pub struct ChannelStore {
     channels_with_admin_privileges: HashSet<ChannelId>,
     outgoing_invites: HashSet<(ChannelId, UserId)>,
     update_channels_tx: mpsc::UnboundedSender<proto::UpdateChannels>,
+    opened_buffers: HashMap<ChannelId, OpenedChannelBuffer>,
     client: Arc<Client>,
     user_store: ModelHandle<UserStore>,
     _rpc_subscription: Subscription,
@@ -57,6 +53,11 @@ pub enum ChannelMemberStatus {
     NotMember,
 }
 
+enum OpenedChannelBuffer {
+    Open(WeakModelHandle<ChannelBuffer>),
+    Loading(Shared<Task<Result<ModelHandle<ChannelBuffer>, Arc<anyhow::Error>>>>),
+}
+
 impl ChannelStore {
     pub fn new(
         client: Arc<Client>,
@@ -70,16 +71,14 @@ impl ChannelStore {
         let mut connection_status = client.status();
         let watch_connection_status = cx.spawn_weak(|this, mut cx| async move {
             while let Some(status) = connection_status.next().await {
-                if matches!(status, Status::ConnectionLost | Status::SignedOut) {
+                if !status.is_connected() {
                     if let Some(this) = this.upgrade(&cx) {
                         this.update(&mut cx, |this, cx| {
-                            this.channels_by_id.clear();
-                            this.channel_invitations.clear();
-                            this.channel_participants.clear();
-                            this.channels_with_admin_privileges.clear();
-                            this.channel_paths.clear();
-                            this.outgoing_invites.clear();
-                            cx.notify();
+                            if matches!(status, Status::ConnectionLost | Status::SignedOut) {
+                                this.handle_disconnect(cx);
+                            } else {
+                                this.disconnect_buffers(cx);
+                            }
                         });
                     } else {
                         break;
@@ -87,6 +86,7 @@ impl ChannelStore {
                 }
             }
         });
+
         Self {
             channels_by_id: HashMap::default(),
             channel_invitations: Vec::default(),
@@ -94,6 +94,7 @@ impl ChannelStore {
             channel_participants: Default::default(),
             channels_with_admin_privileges: Default::default(),
             outgoing_invites: Default::default(),
+            opened_buffers: Default::default(),
             update_channels_tx,
             client,
             user_store,
@@ -114,6 +115,16 @@ impl ChannelStore {
         }
     }
 
+    pub fn has_children(&self, channel_id: ChannelId) -> bool {
+        self.channel_paths.iter().any(|path| {
+            if let Some(ix) = path.iter().position(|id| *id == channel_id) {
+                path.len() > ix + 1
+            } else {
+                false
+            }
+        })
+    }
+
     pub fn channel_count(&self) -> usize {
         self.channel_paths.len()
     }
@@ -141,6 +152,74 @@ impl ChannelStore {
         self.channels_by_id.get(&channel_id)
     }
 
+    pub fn open_channel_buffer(
+        &mut self,
+        channel_id: ChannelId,
+        cx: &mut ModelContext<Self>,
+    ) -> Task<Result<ModelHandle<ChannelBuffer>>> {
+        // Make sure that a given channel buffer is only opened once per
+        // app instance, even if this method is called multiple times
+        // with the same channel id while the first task is still running.
+        let task = loop {
+            match self.opened_buffers.entry(channel_id) {
+                hash_map::Entry::Occupied(e) => match e.get() {
+                    OpenedChannelBuffer::Open(buffer) => {
+                        if let Some(buffer) = buffer.upgrade(cx) {
+                            break Task::ready(Ok(buffer)).shared();
+                        } else {
+                            self.opened_buffers.remove(&channel_id);
+                            continue;
+                        }
+                    }
+                    OpenedChannelBuffer::Loading(task) => break task.clone(),
+                },
+                hash_map::Entry::Vacant(e) => {
+                    let client = self.client.clone();
+                    let task = cx
+                        .spawn(|this, cx| async move {
+                            let channel = this.read_with(&cx, |this, _| {
+                                this.channel_for_id(channel_id).cloned().ok_or_else(|| {
+                                    Arc::new(anyhow!("no channel for id: {}", channel_id))
+                                })
+                            })?;
+
+                            ChannelBuffer::new(channel, client, cx)
+                                .await
+                                .map_err(Arc::new)
+                        })
+                        .shared();
+                    e.insert(OpenedChannelBuffer::Loading(task.clone()));
+                    cx.spawn({
+                        let task = task.clone();
+                        |this, mut cx| async move {
+                            let result = task.await;
+                            this.update(&mut cx, |this, cx| match result {
+                                Ok(buffer) => {
+                                    cx.observe_release(&buffer, move |this, _, _| {
+                                        this.opened_buffers.remove(&channel_id);
+                                    })
+                                    .detach();
+                                    this.opened_buffers.insert(
+                                        channel_id,
+                                        OpenedChannelBuffer::Open(buffer.downgrade()),
+                                    );
+                                }
+                                Err(error) => {
+                                    log::error!("failed to open channel buffer {error:?}");
+                                    this.opened_buffers.remove(&channel_id);
+                                }
+                            });
+                        }
+                    })
+                    .detach();
+                    break task;
+                }
+            }
+        };
+        cx.foreground()
+            .spawn(async move { task.await.map_err(|error| anyhow!("{}", error)) })
+    }
+
     pub fn is_user_admin(&self, channel_id: ChannelId) -> bool {
         self.channel_paths.iter().any(|path| {
             if let Some(ix) = path.iter().position(|id| *id == channel_id) {
@@ -403,6 +482,27 @@ impl ChannelStore {
         Ok(())
     }
 
+    fn handle_disconnect(&mut self, cx: &mut ModelContext<'_, ChannelStore>) {
+        self.disconnect_buffers(cx);
+        self.channels_by_id.clear();
+        self.channel_invitations.clear();
+        self.channel_participants.clear();
+        self.channels_with_admin_privileges.clear();
+        self.channel_paths.clear();
+        self.outgoing_invites.clear();
+        cx.notify();
+    }
+
+    fn disconnect_buffers(&mut self, cx: &mut ModelContext<ChannelStore>) {
+        for (_, buffer) in self.opened_buffers.drain() {
+            if let OpenedChannelBuffer::Open(buffer) = buffer {
+                if let Some(buffer) = buffer.upgrade(cx) {
+                    buffer.update(cx, |buffer, cx| buffer.disconnect(cx));
+                }
+            }
+        }
+    }
+
     pub(crate) fn update_channels(
         &mut self,
         payload: proto::UpdateChannels,
@@ -437,25 +537,30 @@ impl ChannelStore {
                     .retain(|channel_id, _| !payload.remove_channels.contains(channel_id));
                 self.channels_with_admin_privileges
                     .retain(|channel_id| !payload.remove_channels.contains(channel_id));
+
+                for channel_id in &payload.remove_channels {
+                    let channel_id = *channel_id;
+                    if let Some(OpenedChannelBuffer::Open(buffer)) =
+                        self.opened_buffers.remove(&channel_id)
+                    {
+                        if let Some(buffer) = buffer.upgrade(cx) {
+                            buffer.update(cx, ChannelBuffer::disconnect);
+                        }
+                    }
+                }
             }
 
-            for channel in payload.channels {
-                if let Some(existing_channel) = self.channels_by_id.get_mut(&channel.id) {
-                    // FIXME: We may be missing a path for this existing channel in certain cases
-                    let existing_channel = Arc::make_mut(existing_channel);
-                    existing_channel.name = channel.name;
-                    continue;
-                }
+            for channel_proto in payload.channels {
+                if let Some(existing_channel) = self.channels_by_id.get_mut(&channel_proto.id) {
+                    Arc::make_mut(existing_channel).name = channel_proto.name;
+                } else {
+                    let channel = Arc::new(Channel {
+                        id: channel_proto.id,
+                        name: channel_proto.name,
+                    });
+                    self.channels_by_id.insert(channel.id, channel.clone());
 
-                self.channels_by_id.insert(
-                    channel.id,
-                    Arc::new(Channel {
-                        id: channel.id,
-                        name: channel.name,
-                    }),
-                );
-
-                if let Some(parent_id) = channel.parent_id {
+                    if let Some(parent_id) = channel_proto.parent_id {
                         let mut ix = 0;
                         while ix < self.channel_paths.len() {
                             let path = &self.channel_paths[ix];
@@ -471,6 +576,7 @@ impl ChannelStore {
                         self.channel_paths.push(vec![channel.id]);
                     }
                 }
+            }
 
             self.channel_paths.sort_by(|a, b| {
                 let a = Self::channel_path_sorting_key(a, &self.channels_by_id);

crates/channel/src/channel_store_tests.rs

@@ -1,4 +1,7 @@
 use super::*;
+use client::{Client, UserStore};
+use gpui::{AppContext, ModelHandle};
+use rpc::proto;
 use util::http::FakeHttpClient;
 
 #[gpui::test]

crates/client/Cargo.toml

@@ -17,8 +17,9 @@ db = { path = "../db" }
 gpui = { path = "../gpui" }
 util = { path = "../util" }
 rpc = { path = "../rpc" }
+text = { path = "../text" }
 settings = { path = "../settings" }
-staff_mode = { path = "../staff_mode" }
+feature_flags = { path = "../feature_flags" }
 sum_tree = { path = "../sum_tree" }
 
 anyhow.workspace = true

crates/client/src/client.rs

@@ -1,10 +1,6 @@
 #[cfg(any(test, feature = "test-support"))]
 pub mod test;
 
-#[cfg(test)]
-mod channel_store_tests;
-
-pub mod channel_store;
 pub mod telemetry;
 pub mod user;
 
@@ -48,7 +44,6 @@ use util::channel::ReleaseChannel;
 use util::http::HttpClient;
 use util::{ResultExt, TryFutureExt};
 
-pub use channel_store::*;
 pub use rpc::*;
 pub use telemetry::ClickhouseEvent;
 pub use user::*;

crates/client/src/telemetry.rs

@@ -135,8 +135,6 @@ impl Telemetry {
         }
     }
 
-    /// This method takes the entire TelemetrySettings struct in order to force client code
-    /// to pull the struct out of the settings global. Do not remove!
     pub fn set_authenticated_user_info(
         self: &Arc<Self>,
         metrics_id: Option<String>,

crates/client/src/test.rs

@@ -168,6 +168,7 @@ impl FakeServer {
                     GetPrivateUserInfoResponse {
                         metrics_id: "the-metrics-id".into(),
                         staff: false,
+                        flags: Default::default(),
                     },
                 )
                 .await;

crates/client/src/user.rs

@@ -1,18 +1,20 @@
 use super::{proto, Client, Status, TypedEnvelope};
 use anyhow::{anyhow, Context, Result};
 use collections::{hash_map::Entry, HashMap, HashSet};
+use feature_flags::FeatureFlagAppExt;
 use futures::{channel::mpsc, future, AsyncReadExt, Future, StreamExt};
 use gpui::{AsyncAppContext, Entity, ImageData, ModelContext, ModelHandle, Task};
 use postage::{sink::Sink, watch};
 use rpc::proto::{RequestMessage, UsersResponse};
-use staff_mode::StaffMode;
 use std::sync::{Arc, Weak};
 use util::http::HttpClient;
 use util::TryFutureExt as _;
 
+pub type UserId = u64;
+
 #[derive(Default, Debug)]
 pub struct User {
-    pub id: u64,
+    pub id: UserId,
     pub github_login: String,
     pub avatar: Option<Arc<ImageData>>,
 }
@@ -143,26 +145,23 @@ impl UserStore {
                                 let fetch_metrics_id =
                                     client.request(proto::GetPrivateUserInfo {}).log_err();
                                 let (user, info) = futures::join!(fetch_user, fetch_metrics_id);
-                                cx.read(|cx| {
+
+                                if let Some(info) = info {
+                                    cx.update(|cx| {
+                                        cx.update_flags(info.staff, info.flags);
                                         client.telemetry.set_authenticated_user_info(
-                                        info.as_ref().map(|info| info.metrics_id.clone()),
-                                        info.as_ref().map(|info| info.staff).unwrap_or(false),
+                                            Some(info.metrics_id.clone()),
+                                            info.staff,
                                             cx,
                                         )
                                     });
-
-                                cx.update(|cx| {
-                                    cx.update_default_global(|staff_mode: &mut StaffMode, _| {
-                                        if !staff_mode.0 {
-                                            *staff_mode = StaffMode(
-                                                info.as_ref()
-                                                    .map(|info| info.staff)
-                                                    .unwrap_or_default(),
-                                            )
+                                } else {
+                                    cx.read(|cx| {
+                                        client
+                                            .telemetry
+                                            .set_authenticated_user_info(None, false, cx)
+                                    });
                                 }
-                                        ()
-                                    });
-                                });
 
                                 current_user_tx.send(user).await.ok();
 

crates/collab/Cargo.toml

@@ -3,7 +3,7 @@ authors = ["Nathan Sobo <nathan@zed.dev>"]
 default-run = "collab"
 edition = "2021"
 name = "collab"
-version = "0.17.0"
+version = "0.18.0"
 publish = false
 
 [[bin]]
@@ -14,8 +14,10 @@ name = "seed"
 required-features = ["seed-support"]
 
 [dependencies]
+clock = { path = "../clock" }
 collections = { path = "../collections" }
 live_kit_server = { path = "../live_kit_server" }
+text = { path = "../text" }
 rpc = { path = "../rpc" }
 util = { path = "../util" }
 
@@ -35,6 +37,7 @@ log.workspace = true
 nanoid = "0.4"
 parking_lot.workspace = true
 prometheus = "0.13"
+prost.workspace = true
 rand.workspace = true
 reqwest = { version = "0.11", features = ["json"], optional = true }
 scrypt = "0.7"
@@ -62,6 +65,7 @@ collections = { path = "../collections", features = ["test-support"] }
 gpui = { path = "../gpui", features = ["test-support"] }
 call = { path = "../call", features = ["test-support"] }
 client = { path = "../client", features = ["test-support"] }
+channel = { path = "../channel" }
 editor = { path = "../editor", features = ["test-support"] }
 language = { path = "../language", features = ["test-support"] }
 fs = { path = "../fs", features = ["test-support"] }
@@ -74,6 +78,7 @@ rpc = { path = "../rpc", features = ["test-support"] }
 settings = { path = "../settings", features = ["test-support"] }
 theme = { path = "../theme" }
 workspace = { path = "../workspace", features = ["test-support"] }
+collab_ui = { path = "../collab_ui", features = ["test-support"] }
 
 ctor.workspace = true
 env_logger.workspace = true

crates/collab/migrations.sqlite/20221109000000_test_schema.sql

@@ -208,3 +208,63 @@ CREATE TABLE "channel_members" (
 );
 
 CREATE UNIQUE INDEX "index_channel_members_on_channel_id_and_user_id" ON "channel_members" ("channel_id", "user_id");
+
+CREATE TABLE "buffers" (
+    "id" INTEGER PRIMARY KEY AUTOINCREMENT,
+    "channel_id" INTEGER NOT NULL REFERENCES channels (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL DEFAULT 0
+);
+
+CREATE INDEX "index_buffers_on_channel_id" ON "buffers" ("channel_id");
+
+CREATE TABLE "buffer_operations" (
+    "buffer_id" INTEGER NOT NULL REFERENCES buffers (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL,
+    "replica_id" INTEGER NOT NULL,
+    "lamport_timestamp" INTEGER NOT NULL,
+    "value" BLOB NOT NULL,
+    PRIMARY KEY(buffer_id, epoch, lamport_timestamp, replica_id)
+);
+
+CREATE TABLE "buffer_snapshots" (
+    "buffer_id" INTEGER NOT NULL REFERENCES buffers (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL,
+    "text" TEXT NOT NULL,
+    "operation_serialization_version" INTEGER NOT NULL,
+    PRIMARY KEY(buffer_id, epoch)
+);
+
+CREATE TABLE "channel_buffer_collaborators" (
+    "id" INTEGER PRIMARY KEY AUTOINCREMENT,
+    "channel_id" INTEGER NOT NULL REFERENCES channels (id) ON DELETE CASCADE,
+    "connection_id" INTEGER NOT NULL,
+    "connection_server_id" INTEGER NOT NULL REFERENCES servers (id) ON DELETE CASCADE,
+    "connection_lost" BOOLEAN NOT NULL DEFAULT false,
+    "user_id" INTEGER NOT NULL REFERENCES users (id) ON DELETE CASCADE,
+    "replica_id" INTEGER NOT NULL
+);
+
+CREATE INDEX "index_channel_buffer_collaborators_on_channel_id" ON "channel_buffer_collaborators" ("channel_id");
+CREATE UNIQUE INDEX "index_channel_buffer_collaborators_on_channel_id_and_replica_id" ON "channel_buffer_collaborators" ("channel_id", "replica_id");
+CREATE INDEX "index_channel_buffer_collaborators_on_connection_server_id" ON "channel_buffer_collaborators" ("connection_server_id");
+CREATE INDEX "index_channel_buffer_collaborators_on_connection_id" ON "channel_buffer_collaborators" ("connection_id");
+CREATE UNIQUE INDEX "index_channel_buffer_collaborators_on_channel_id_connection_id_and_server_id" ON "channel_buffer_collaborators" ("channel_id", "connection_id", "connection_server_id");
+
+
+CREATE TABLE "feature_flags" (
+    "id" INTEGER PRIMARY KEY AUTOINCREMENT,
+    "flag" TEXT NOT NULL UNIQUE
+);
+
+CREATE INDEX "index_feature_flags" ON "feature_flags" ("id");
+
+
+CREATE TABLE "user_features" (
+    "user_id" INTEGER NOT NULL REFERENCES users (id) ON DELETE CASCADE,
+    "feature_id" INTEGER NOT NULL REFERENCES feature_flags (id) ON DELETE CASCADE,
+    PRIMARY KEY (user_id, feature_id)
+);
+
+CREATE UNIQUE INDEX "index_user_features_user_id_and_feature_id" ON "user_features" ("user_id", "feature_id");
+CREATE INDEX "index_user_features_on_user_id" ON "user_features" ("user_id");
+CREATE INDEX "index_user_features_on_feature_id" ON "user_features" ("feature_id");

crates/collab/migrations/20230819154600_add_channel_buffers.sql

@@ -0,0 +1,40 @@
+CREATE TABLE "buffers" (
+    "id" SERIAL PRIMARY KEY,
+    "channel_id" INTEGER NOT NULL REFERENCES channels (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL DEFAULT 0
+);
+
+CREATE INDEX "index_buffers_on_channel_id" ON "buffers" ("channel_id");
+
+CREATE TABLE "buffer_operations" (
+    "buffer_id" INTEGER NOT NULL REFERENCES buffers (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL,
+    "replica_id" INTEGER NOT NULL,
+    "lamport_timestamp" INTEGER NOT NULL,
+    "value" BYTEA NOT NULL,
+    PRIMARY KEY(buffer_id, epoch, lamport_timestamp, replica_id)
+);
+
+CREATE TABLE "buffer_snapshots" (
+    "buffer_id" INTEGER NOT NULL REFERENCES buffers (id) ON DELETE CASCADE,
+    "epoch" INTEGER NOT NULL,
+    "text" TEXT NOT NULL,
+    "operation_serialization_version" INTEGER NOT NULL,
+    PRIMARY KEY(buffer_id, epoch)
+);
+
+CREATE TABLE "channel_buffer_collaborators" (
+    "id" SERIAL PRIMARY KEY,
+    "channel_id" INTEGER NOT NULL REFERENCES channels (id) ON DELETE CASCADE,
+    "connection_id" INTEGER NOT NULL,
+    "connection_server_id" INTEGER NOT NULL REFERENCES servers (id) ON DELETE CASCADE,
+    "connection_lost" BOOLEAN NOT NULL DEFAULT FALSE,
+    "user_id" INTEGER NOT NULL REFERENCES users (id) ON DELETE CASCADE,
+    "replica_id" INTEGER NOT NULL
+);
+
+CREATE INDEX "index_channel_buffer_collaborators_on_channel_id" ON "channel_buffer_collaborators" ("channel_id");
+CREATE UNIQUE INDEX "index_channel_buffer_collaborators_on_channel_id_and_replica_id" ON "channel_buffer_collaborators" ("channel_id", "replica_id");
+CREATE INDEX "index_channel_buffer_collaborators_on_connection_server_id" ON "channel_buffer_collaborators" ("connection_server_id");
+CREATE INDEX "index_channel_buffer_collaborators_on_connection_id" ON "channel_buffer_collaborators" ("connection_id");
+CREATE UNIQUE INDEX "index_channel_buffer_collaborators_on_channel_id_connection_id_and_server_id" ON "channel_buffer_collaborators" ("channel_id", "connection_id", "connection_server_id");

crates/collab/migrations/20230825190322_add_server_feature_flags.sql

@@ -0,0 +1,16 @@
+CREATE TABLE "feature_flags" (
+    "id" SERIAL PRIMARY KEY,
+    "flag" VARCHAR(255) NOT NULL UNIQUE
+);
+
+CREATE UNIQUE INDEX "index_feature_flags" ON "feature_flags" ("id");
+
+CREATE TABLE "user_features" (
+    "user_id" INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    "feature_id" INTEGER NOT NULL REFERENCES feature_flags(id) ON DELETE CASCADE,
+    PRIMARY KEY (user_id, feature_id)
+);
+
+CREATE UNIQUE INDEX "index_user_features_user_id_and_feature_id" ON "user_features" ("user_id", "feature_id");
+CREATE INDEX "index_user_features_on_user_id" ON "user_features" ("user_id");
+CREATE INDEX "index_user_features_on_feature_id" ON "user_features" ("feature_id");

crates/collab/src/db.rs

@@ -1,7 +1,8 @@
 #[cfg(test)]
-mod db_tests;
+pub mod tests;
+
 #[cfg(test)]
-pub mod test_db;
+pub use tests::TestDb;
 
 mod ids;
 mod queries;
@@ -52,6 +53,8 @@ pub struct Database {
     runtime: Option<tokio::runtime::Runtime>,
 }
 
+// The `Database` type has so many methods that its impl blocks are split into
+// separate files in the `queries` folder.
 impl Database {
     pub async fn new(options: ConnectOptions, executor: Executor) -> Result<Self> {
         Ok(Self {
@@ -246,7 +249,9 @@ impl Database {
         let mut tx = Arc::new(Some(tx));
         let result = f(TransactionHandle(tx.clone())).await;
         let Some(tx) = Arc::get_mut(&mut tx).and_then(|tx| tx.take()) else {
-            return Err(anyhow!("couldn't complete transaction because it's still in use"))?;
+            return Err(anyhow!(
+                "couldn't complete transaction because it's still in use"
+            ))?;
         };
 
         Ok((tx, result))

crates/collab/src/db/ids.rs

@@ -110,6 +110,7 @@ fn value_to_integer(v: Value) -> Result<i32, ValueTypeErr> {
     }
 }
 
+id_type!(BufferId);
 id_type!(AccessTokenId);
 id_type!(ChannelId);
 id_type!(ChannelMemberId);
@@ -123,3 +124,5 @@ id_type!(ReplicaId);
 id_type!(ServerId);
 id_type!(SignupId);
 id_type!(UserId);
+id_type!(ChannelBufferCollaboratorId);
+id_type!(FlagId);

crates/collab/src/db/queries.rs

@@ -1,6 +1,7 @@
 use super::*;
 
 pub mod access_tokens;
+pub mod buffers;
 pub mod channels;
 pub mod contacts;
 pub mod projects;

crates/collab/src/db/queries/buffers.rs

@@ -0,0 +1,588 @@
+use super::*;
+use prost::Message;
+use text::{EditOperation, InsertionTimestamp, UndoOperation};
+
+impl Database {
+    pub async fn join_channel_buffer(
+        &self,
+        channel_id: ChannelId,
+        user_id: UserId,
+        connection: ConnectionId,
+    ) -> Result<proto::JoinChannelBufferResponse> {
+        self.transaction(|tx| async move {
+            let tx = tx;
+
+            self.check_user_is_channel_member(channel_id, user_id, &tx)
+                .await?;
+
+            let buffer = channel::Model {
+                id: channel_id,
+                ..Default::default()
+            }
+            .find_related(buffer::Entity)
+            .one(&*tx)
+            .await?;
+
+            let buffer = if let Some(buffer) = buffer {
+                buffer
+            } else {
+                let buffer = buffer::ActiveModel {
+                    channel_id: ActiveValue::Set(channel_id),
+                    ..Default::default()
+                }
+                .insert(&*tx)
+                .await?;
+                buffer_snapshot::ActiveModel {
+                    buffer_id: ActiveValue::Set(buffer.id),
+                    epoch: ActiveValue::Set(0),
+                    text: ActiveValue::Set(String::new()),
+                    operation_serialization_version: ActiveValue::Set(
+                        storage::SERIALIZATION_VERSION,
+                    ),
+                }
+                .insert(&*tx)
+                .await?;
+                buffer
+            };
+
+            // Join the collaborators
+            let mut collaborators = channel_buffer_collaborator::Entity::find()
+                .filter(channel_buffer_collaborator::Column::ChannelId.eq(channel_id))
+                .all(&*tx)
+                .await?;
+            let replica_ids = collaborators
+                .iter()
+                .map(|c| c.replica_id)
+                .collect::<HashSet<_>>();
+            let mut replica_id = ReplicaId(0);
+            while replica_ids.contains(&replica_id) {
+                replica_id.0 += 1;
+            }
+            let collaborator = channel_buffer_collaborator::ActiveModel {
+                channel_id: ActiveValue::Set(channel_id),
+                connection_id: ActiveValue::Set(connection.id as i32),
+                connection_server_id: ActiveValue::Set(ServerId(connection.owner_id as i32)),
+                user_id: ActiveValue::Set(user_id),
+                replica_id: ActiveValue::Set(replica_id),
+                ..Default::default()
+            }
+            .insert(&*tx)
+            .await?;
+            collaborators.push(collaborator);
+
+            // Assemble the buffer state
+            let (base_text, operations) = self.get_buffer_state(&buffer, &tx).await?;
+
+            Ok(proto::JoinChannelBufferResponse {
+                buffer_id: buffer.id.to_proto(),
+                replica_id: replica_id.to_proto() as u32,
+                base_text,
+                operations,
+                collaborators: collaborators
+                    .into_iter()
+                    .map(|collaborator| proto::Collaborator {
+                        peer_id: Some(collaborator.connection().into()),
+                        user_id: collaborator.user_id.to_proto(),
+                        replica_id: collaborator.replica_id.0 as u32,
+                    })
+                    .collect(),
+            })
+        })
+        .await
+    }
+
+    pub async fn leave_channel_buffer(
+        &self,
+        channel_id: ChannelId,
+        connection: ConnectionId,
+    ) -> Result<Vec<ConnectionId>> {
+        self.transaction(|tx| async move {
+            self.leave_channel_buffer_internal(channel_id, connection, &*tx)
+                .await
+        })
+        .await
+    }
+
+    pub async fn leave_channel_buffer_internal(
+        &self,
+        channel_id: ChannelId,
+        connection: ConnectionId,
+        tx: &DatabaseTransaction,
+    ) -> Result<Vec<ConnectionId>> {
+        let result = channel_buffer_collaborator::Entity::delete_many()
+            .filter(
+                Condition::all()
+                    .add(channel_buffer_collaborator::Column::ChannelId.eq(channel_id))
+                    .add(channel_buffer_collaborator::Column::ConnectionId.eq(connection.id as i32))
+                    .add(
+                        channel_buffer_collaborator::Column::ConnectionServerId
+                            .eq(connection.owner_id as i32),
+                    ),
+            )
+            .exec(&*tx)
+            .await?;
+        if result.rows_affected == 0 {
+            Err(anyhow!("not a collaborator on this project"))?;
+        }
+
+        let mut connections = Vec::new();
+        let mut rows = channel_buffer_collaborator::Entity::find()
+            .filter(
+                Condition::all().add(channel_buffer_collaborator::Column::ChannelId.eq(channel_id)),
+            )
+            .stream(&*tx)
+            .await?;
+        while let Some(row) = rows.next().await {
+            let row = row?;
+            connections.push(ConnectionId {
+                id: row.connection_id as u32,
+                owner_id: row.connection_server_id.0 as u32,
+            });
+        }
+
+        drop(rows);
+
+        if connections.is_empty() {
+            self.snapshot_buffer(channel_id, &tx).await?;
+        }
+
+        Ok(connections)
+    }
+
+    pub async fn leave_channel_buffers(
+        &self,
+        connection: ConnectionId,
+    ) -> Result<Vec<(ChannelId, Vec<ConnectionId>)>> {
+        self.transaction(|tx| async move {
+            #[derive(Debug, Clone, Copy, EnumIter, DeriveColumn)]
+            enum QueryChannelIds {
+                ChannelId,
+            }
+
+            let channel_ids: Vec<ChannelId> = channel_buffer_collaborator::Entity::find()
+                .select_only()
+                .column(channel_buffer_collaborator::Column::ChannelId)
+                .filter(Condition::all().add(
+                    channel_buffer_collaborator::Column::ConnectionId.eq(connection.id as i32),
+                ))
+                .into_values::<_, QueryChannelIds>()
+                .all(&*tx)
+                .await?;
+
+            let mut result = Vec::new();
+            for channel_id in channel_ids {
+                let collaborators = self
+                    .leave_channel_buffer_internal(channel_id, connection, &*tx)
+                    .await?;
+                result.push((channel_id, collaborators));
+            }
+
+            Ok(result)
+        })
+        .await
+    }
+
+    #[cfg(debug_assertions)]
+    pub async fn get_channel_buffer_collaborators(
+        &self,
+        channel_id: ChannelId,
+    ) -> Result<Vec<UserId>> {
+        self.transaction(|tx| async move {
+            #[derive(Debug, Clone, Copy, EnumIter, DeriveColumn)]
+            enum QueryUserIds {
+                UserId,
+            }
+
+            let users: Vec<UserId> = channel_buffer_collaborator::Entity::find()
+                .select_only()
+                .column(channel_buffer_collaborator::Column::UserId)
+                .filter(
+                    Condition::all()
+                        .add(channel_buffer_collaborator::Column::ChannelId.eq(channel_id)),
+                )
+                .into_values::<_, QueryUserIds>()
+                .all(&*tx)
+                .await?;
+
+            Ok(users)
+        })
+        .await
+    }
+
+    pub async fn update_channel_buffer(
+        &self,
+        channel_id: ChannelId,
+        user: UserId,
+        operations: &[proto::Operation],
+    ) -> Result<Vec<ConnectionId>> {
+        self.transaction(move |tx| async move {
+            self.check_user_is_channel_member(channel_id, user, &*tx)
+                .await?;
+
+            let buffer = buffer::Entity::find()
+                .filter(buffer::Column::ChannelId.eq(channel_id))
+                .one(&*tx)
+                .await?
+                .ok_or_else(|| anyhow!("no such buffer"))?;
+
+            #[derive(Debug, Clone, Copy, EnumIter, DeriveColumn)]
+            enum QueryVersion {
+                OperationSerializationVersion,
+            }
+
+            let serialization_version: i32 = buffer
+                .find_related(buffer_snapshot::Entity)
+                .select_only()
+                .column(buffer_snapshot::Column::OperationSerializationVersion)
+                .filter(buffer_snapshot::Column::Epoch.eq(buffer.epoch))
+                .into_values::<_, QueryVersion>()
+                .one(&*tx)
+                .await?
+                .ok_or_else(|| anyhow!("missing buffer snapshot"))?;
+
+            let operations = operations
+                .iter()
+                .filter_map(|op| operation_to_storage(op, &buffer, serialization_version))
+                .collect::<Vec<_>>();
+            if !operations.is_empty() {
+                buffer_operation::Entity::insert_many(operations)
+                    .exec(&*tx)
+                    .await?;
+            }
+
+            let mut connections = Vec::new();
+            let mut rows = channel_buffer_collaborator::Entity::find()
+                .filter(
+                    Condition::all()
+                        .add(channel_buffer_collaborator::Column::ChannelId.eq(channel_id)),
+                )
+                .stream(&*tx)
+                .await?;
+            while let Some(row) = rows.next().await {
+                let row = row?;
+                connections.push(ConnectionId {
+                    id: row.connection_id as u32,
+                    owner_id: row.connection_server_id.0 as u32,
+                });
+            }
+
+            Ok(connections)
+        })
+        .await
+    }
+
+    async fn get_buffer_state(
+        &self,
+        buffer: &buffer::Model,
+        tx: &DatabaseTransaction,
+    ) -> Result<(String, Vec<proto::Operation>)> {
+        let id = buffer.id;
+        let (base_text, version) = if buffer.epoch > 0 {
+            let snapshot = buffer_snapshot::Entity::find()
+                .filter(
+                    buffer_snapshot::Column::BufferId
+                        .eq(id)
+                        .and(buffer_snapshot::Column::Epoch.eq(buffer.epoch)),
+                )
+                .one(&*tx)
+                .await?
+                .ok_or_else(|| anyhow!("no such snapshot"))?;
+
+            let version = snapshot.operation_serialization_version;
+            (snapshot.text, version)
+        } else {
+            (String::new(), storage::SERIALIZATION_VERSION)
+        };
+
+        let mut rows = buffer_operation::Entity::find()
+            .filter(
+                buffer_operation::Column::BufferId
+                    .eq(id)
+                    .and(buffer_operation::Column::Epoch.eq(buffer.epoch)),
+            )
+            .stream(&*tx)
+            .await?;
+        let mut operations = Vec::new();
+        while let Some(row) = rows.next().await {
+            let row = row?;
+
+            let operation = operation_from_storage(row, version)?;
+            operations.push(proto::Operation {
+                variant: Some(operation),
+            })
+        }
+
+        Ok((base_text, operations))
+    }
+
+    async fn snapshot_buffer(&self, channel_id: ChannelId, tx: &DatabaseTransaction) -> Result<()> {
+        let buffer = channel::Model {
+            id: channel_id,
+            ..Default::default()
+        }
+        .find_related(buffer::Entity)
+        .one(&*tx)
+        .await?
+        .ok_or_else(|| anyhow!("no such buffer"))?;
+
+        let (base_text, operations) = self.get_buffer_state(&buffer, tx).await?;
+        if operations.is_empty() {
+            return Ok(());
+        }
+
+        let mut text_buffer = text::Buffer::new(0, 0, base_text);
+        text_buffer
+            .apply_ops(operations.into_iter().filter_map(operation_from_wire))
+            .unwrap();
+
+        let base_text = text_buffer.text();
+        let epoch = buffer.epoch + 1;
+
+        buffer_snapshot::Model {
+            buffer_id: buffer.id,
+            epoch,
+            text: base_text,
+            operation_serialization_version: storage::SERIALIZATION_VERSION,
+        }
+        .into_active_model()
+        .insert(tx)
+        .await?;
+
+        buffer::ActiveModel {
+            id: ActiveValue::Unchanged(buffer.id),
+            epoch: ActiveValue::Set(epoch),
+            ..Default::default()
+        }
+        .save(tx)
+        .await?;
+
+        Ok(())
+    }
+}
+
+fn operation_to_storage(
+    operation: &proto::Operation,
+    buffer: &buffer::Model,
+    _format: i32,
+) -> Option<buffer_operation::ActiveModel> {
+    let (replica_id, lamport_timestamp, value) = match operation.variant.as_ref()? {
+        proto::operation::Variant::Edit(operation) => (
+            operation.replica_id,
+            operation.lamport_timestamp,
+            storage::Operation {
+                local_timestamp: operation.local_timestamp,
+                version: version_to_storage(&operation.version),
+                is_undo: false,
+                edit_ranges: operation
+                    .ranges
+                    .iter()
+                    .map(|range| storage::Range {
+                        start: range.start,
+                        end: range.end,
+                    })
+                    .collect(),
+                edit_texts: operation.new_text.clone(),
+                undo_counts: Vec::new(),
+            },
+        ),
+        proto::operation::Variant::Undo(operation) => (
+            operation.replica_id,
+            operation.lamport_timestamp,
+            storage::Operation {
+                local_timestamp: operation.local_timestamp,
+                version: version_to_storage(&operation.version),
+                is_undo: true,
+                edit_ranges: Vec::new(),
+                edit_texts: Vec::new(),
+                undo_counts: operation
+                    .counts
+                    .iter()
+                    .map(|entry| storage::UndoCount {
+                        replica_id: entry.replica_id,
+                        local_timestamp: entry.local_timestamp,
+                        count: entry.count,
+                    })
+                    .collect(),
+            },
+        ),
+        _ => None?,
+    };
+
+    Some(buffer_operation::ActiveModel {
+        buffer_id: ActiveValue::Set(buffer.id),
+        epoch: ActiveValue::Set(buffer.epoch),
+        replica_id: ActiveValue::Set(replica_id as i32),
+        lamport_timestamp: ActiveValue::Set(lamport_timestamp as i32),
+        value: ActiveValue::Set(value.encode_to_vec()),
+    })
+}
+
+fn operation_from_storage(
+    row: buffer_operation::Model,
+    _format_version: i32,
+) -> Result<proto::operation::Variant, Error> {
+    let operation =
+        storage::Operation::decode(row.value.as_slice()).map_err(|error| anyhow!("{}", error))?;
+    let version = version_from_storage(&operation.version);
+    Ok(if operation.is_undo {
+        proto::operation::Variant::Undo(proto::operation::Undo {
+            replica_id: row.replica_id as u32,
+            local_timestamp: operation.local_timestamp as u32,
+            lamport_timestamp: row.lamport_timestamp as u32,
+            version,
+            counts: operation
+                .undo_counts
+                .iter()
+                .map(|entry| proto::UndoCount {
+                    replica_id: entry.replica_id,
+                    local_timestamp: entry.local_timestamp,
+                    count: entry.count,
+                })
+                .collect(),
+        })
+    } else {
+        proto::operation::Variant::Edit(proto::operation::Edit {
+            replica_id: row.replica_id as u32,
+            local_timestamp: operation.local_timestamp as u32,
+            lamport_timestamp: row.lamport_timestamp as u32,
+            version,
+            ranges: operation
+                .edit_ranges
+                .into_iter()
+                .map(|range| proto::Range {
+                    start: range.start,
+                    end: range.end,
+                })
+                .collect(),
+            new_text: operation.edit_texts,
+        })
+    })
+}
+
+fn version_to_storage(version: &Vec<proto::VectorClockEntry>) -> Vec<storage::VectorClockEntry> {
+    version
+        .iter()
+        .map(|entry| storage::VectorClockEntry {
+            replica_id: entry.replica_id,
+            timestamp: entry.timestamp,
+        })
+        .collect()
+}
+
+fn version_from_storage(version: &Vec<storage::VectorClockEntry>) -> Vec<proto::VectorClockEntry> {
+    version
+        .iter()
+        .map(|entry| proto::VectorClockEntry {
+            replica_id: entry.replica_id,
+            timestamp: entry.timestamp,
+        })
+        .collect()
+}
+
+// This is currently a manual copy of the deserialization code in the client's langauge crate
+pub fn operation_from_wire(operation: proto::Operation) -> Option<text::Operation> {
+    match operation.variant? {
+        proto::operation::Variant::Edit(edit) => Some(text::Operation::Edit(EditOperation {
+            timestamp: InsertionTimestamp {
+                replica_id: edit.replica_id as text::ReplicaId,
+                local: edit.local_timestamp,
+                lamport: edit.lamport_timestamp,
+            },
+            version: version_from_wire(&edit.version),
+            ranges: edit
+                .ranges
+                .into_iter()
+                .map(|range| {
+                    text::FullOffset(range.start as usize)..text::FullOffset(range.end as usize)
+                })
+                .collect(),
+            new_text: edit.new_text.into_iter().map(Arc::from).collect(),
+        })),
+        proto::operation::Variant::Undo(undo) => Some(text::Operation::Undo {
+            lamport_timestamp: clock::Lamport {
+                replica_id: undo.replica_id as text::ReplicaId,
+                value: undo.lamport_timestamp,
+            },
+            undo: UndoOperation {
+                id: clock::Local {
+                    replica_id: undo.replica_id as text::ReplicaId,
+                    value: undo.local_timestamp,
+                },
+                version: version_from_wire(&undo.version),
+                counts: undo
+                    .counts
+                    .into_iter()
+                    .map(|c| {
+                        (
+                            clock::Local {
+                                replica_id: c.replica_id as text::ReplicaId,
+                                value: c.local_timestamp,
+                            },
+                            c.count,
+                        )
+                    })
+                    .collect(),
+            },
+        }),
+        _ => None,
+    }
+}
+
+fn version_from_wire(message: &[proto::VectorClockEntry]) -> clock::Global {
+    let mut version = clock::Global::new();
+    for entry in message {
+        version.observe(clock::Local {
+            replica_id: entry.replica_id as text::ReplicaId,
+            value: entry.timestamp,
+        });
+    }
+    version
+}
+
+mod storage {
+    #![allow(non_snake_case)]
+    use prost::Message;
+    pub const SERIALIZATION_VERSION: i32 = 1;
+
+    #[derive(Message)]
+    pub struct Operation {
+        #[prost(uint32, tag = "1")]
+        pub local_timestamp: u32,
+        #[prost(message, repeated, tag = "2")]
+        pub version: Vec<VectorClockEntry>,
+        #[prost(bool, tag = "3")]
+        pub is_undo: bool,
+        #[prost(message, repeated, tag = "4")]
+        pub edit_ranges: Vec<Range>,
+        #[prost(string, repeated, tag = "5")]
+        pub edit_texts: Vec<String>,
+        #[prost(message, repeated, tag = "6")]
+        pub undo_counts: Vec<UndoCount>,
+    }
+
+    #[derive(Message)]
+    pub struct VectorClockEntry {
+        #[prost(uint32, tag = "1")]
+        pub replica_id: u32,
+        #[prost(uint32, tag = "2")]
+        pub timestamp: u32,
+    }
+
+    #[derive(Message)]
+    pub struct Range {
+        #[prost(uint64, tag = "1")]
+        pub start: u64,
+        #[prost(uint64, tag = "2")]
+        pub end: u64,
+    }
+
+    #[derive(Message)]
+    pub struct UndoCount {
+        #[prost(uint32, tag = "1")]
+        pub replica_id: u32,
+        #[prost(uint32, tag = "2")]
+        pub local_timestamp: u32,
+        #[prost(uint32, tag = "3")]
+        pub count: u32,
+    }
+}

crates/collab/src/db/queries/rooms.rs

@@ -465,9 +465,9 @@ impl Database {
             let mut rejoined_projects = Vec::new();
             for rejoined_project in &rejoin_room.rejoined_projects {
                 let project_id = ProjectId::from_proto(rejoined_project.id);
-                let Some(project) = project::Entity::find_by_id(project_id)
-                    .one(&*tx)
-                    .await? else { continue };
+                let Some(project) = project::Entity::find_by_id(project_id).one(&*tx).await? else {
+                    continue;
+                };
 
                 let mut worktrees = Vec::new();
                 let db_worktrees = project.find_related(worktree::Entity).all(&*tx).await?;
@@ -903,15 +903,35 @@ impl Database {
                         ),
                 )
                 .one(&*tx)
-                .await?
-                .ok_or_else(|| anyhow!("not a participant in any room"))?;
+                .await?;
 
+            if let Some(participant) = participant {
                 room_participant::Entity::update(room_participant::ActiveModel {
                     answering_connection_lost: ActiveValue::set(true),
                     ..participant.into_active_model()
                 })
                 .exec(&*tx)
                 .await?;
+            }
+
+            channel_buffer_collaborator::Entity::update_many()
+                .filter(
+                    Condition::all()
+                        .add(
+                            channel_buffer_collaborator::Column::ConnectionId
+                                .eq(connection.id as i32),
+                        )
+                        .add(
+                            channel_buffer_collaborator::Column::ConnectionServerId
+                                .eq(connection.owner_id as i32),
+                        ),
+                )
+                .set(channel_buffer_collaborator::ActiveModel {
+                    connection_lost: ActiveValue::set(true),
+                    ..Default::default()
+                })
+                .exec(&*tx)
+                .await?;
 
             Ok(())
         })

crates/collab/src/db/queries/users.rs

@@ -240,4 +240,58 @@ impl Database {
         result.push('%');
         result
     }
+
+    #[cfg(debug_assertions)]
+    pub async fn create_user_flag(&self, flag: &str) -> Result<FlagId> {
+        self.transaction(|tx| async move {
+            let flag = feature_flag::Entity::insert(feature_flag::ActiveModel {
+                flag: ActiveValue::set(flag.to_string()),
+                ..Default::default()
+            })
+            .exec(&*tx)
+            .await?
+            .last_insert_id;
+
+            Ok(flag)
+        })
+        .await
+    }
+
+    #[cfg(debug_assertions)]
+    pub async fn add_user_flag(&self, user: UserId, flag: FlagId) -> Result<()> {
+        self.transaction(|tx| async move {
+            user_feature::Entity::insert(user_feature::ActiveModel {
+                user_id: ActiveValue::set(user),
+                feature_id: ActiveValue::set(flag),
+            })
+            .exec(&*tx)
+            .await?;
+
+            Ok(())
+        })
+        .await
+    }
+
+    pub async fn get_user_flags(&self, user: UserId) -> Result<Vec<String>> {
+        self.transaction(|tx| async move {
+            #[derive(Copy, Clone, Debug, EnumIter, DeriveColumn)]
+            enum QueryAs {
+                Flag,
+            }
+
+            let flags = user::Model {
+                id: user,
+                ..Default::default()
+            }
+            .find_linked(user::UserFlags)
+            .select_only()
+            .column(feature_flag::Column::Flag)
+            .into_values::<_, QueryAs>()
+            .all(&*tx)
+            .await?;
+
+            Ok(flags)
+        })
+        .await
+    }
 }

crates/collab/src/db/tables.rs

@@ -1,8 +1,13 @@
 pub mod access_token;
+pub mod buffer;
+pub mod buffer_operation;
+pub mod buffer_snapshot;
 pub mod channel;
+pub mod channel_buffer_collaborator;
 pub mod channel_member;
 pub mod channel_path;
 pub mod contact;
+pub mod feature_flag;
 pub mod follower;
 pub mod language_server;
 pub mod project;
@@ -12,6 +17,7 @@ pub mod room_participant;
 pub mod server;
 pub mod signup;
 pub mod user;
+pub mod user_feature;
 pub mod worktree;
 pub mod worktree_diagnostic_summary;
 pub mod worktree_entry;

crates/collab/src/db/tables/buffer.rs

@@ -0,0 +1,45 @@
+use crate::db::{BufferId, ChannelId};
+use sea_orm::entity::prelude::*;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "buffers")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: BufferId,
+    pub epoch: i32,
+    pub channel_id: ChannelId,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(has_many = "super::buffer_operation::Entity")]
+    Operations,
+    #[sea_orm(has_many = "super::buffer_snapshot::Entity")]
+    Snapshots,
+    #[sea_orm(
+        belongs_to = "super::channel::Entity",
+        from = "Column::ChannelId",
+        to = "super::channel::Column::Id"
+    )]
+    Channel,
+}
+
+impl Related<super::buffer_operation::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Operations.def()
+    }
+}
+
+impl Related<super::buffer_snapshot::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Snapshots.def()
+    }
+}
+
+impl Related<super::channel::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Channel.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/tables/buffer_operation.rs

@@ -0,0 +1,34 @@
+use crate::db::BufferId;
+use sea_orm::entity::prelude::*;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "buffer_operations")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub buffer_id: BufferId,
+    #[sea_orm(primary_key)]
+    pub epoch: i32,
+    #[sea_orm(primary_key)]
+    pub lamport_timestamp: i32,
+    #[sea_orm(primary_key)]
+    pub replica_id: i32,
+    pub value: Vec<u8>,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(
+        belongs_to = "super::buffer::Entity",
+        from = "Column::BufferId",
+        to = "super::buffer::Column::Id"
+    )]
+    Buffer,
+}
+
+impl Related<super::buffer::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Buffer.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/tables/buffer_snapshot.rs

@@ -0,0 +1,31 @@
+use crate::db::BufferId;
+use sea_orm::entity::prelude::*;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "buffer_snapshots")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub buffer_id: BufferId,
+    #[sea_orm(primary_key)]
+    pub epoch: i32,
+    pub text: String,
+    pub operation_serialization_version: i32,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(
+        belongs_to = "super::buffer::Entity",
+        from = "Column::BufferId",
+        to = "super::buffer::Column::Id"
+    )]
+    Buffer,
+}
+
+impl Related<super::buffer::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Buffer.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/tables/channel.rs

@@ -15,8 +15,12 @@ impl ActiveModelBehavior for ActiveModel {}
 pub enum Relation {
     #[sea_orm(has_one = "super::room::Entity")]
     Room,
+    #[sea_orm(has_one = "super::buffer::Entity")]
+    Buffer,
     #[sea_orm(has_many = "super::channel_member::Entity")]
     Member,
+    #[sea_orm(has_many = "super::channel_buffer_collaborator::Entity")]
+    BufferCollaborators,
 }
 
 impl Related<super::channel_member::Entity> for Entity {
@@ -30,3 +34,15 @@ impl Related<super::room::Entity> for Entity {
         Relation::Room.def()
     }
 }
+
+impl Related<super::buffer::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Buffer.def()
+    }
+}
+
+impl Related<super::channel_buffer_collaborator::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::BufferCollaborators.def()
+    }
+}

crates/collab/src/db/tables/channel_buffer_collaborator.rs

@@ -0,0 +1,43 @@
+use crate::db::{ChannelBufferCollaboratorId, ChannelId, ReplicaId, ServerId, UserId};
+use rpc::ConnectionId;
+use sea_orm::entity::prelude::*;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "channel_buffer_collaborators")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: ChannelBufferCollaboratorId,
+    pub channel_id: ChannelId,
+    pub connection_id: i32,
+    pub connection_server_id: ServerId,
+    pub connection_lost: bool,
+    pub user_id: UserId,
+    pub replica_id: ReplicaId,
+}
+
+impl Model {
+    pub fn connection(&self) -> ConnectionId {
+        ConnectionId {
+            owner_id: self.connection_server_id.0 as u32,
+            id: self.connection_id as u32,
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(
+        belongs_to = "super::channel::Entity",
+        from = "Column::ChannelId",
+        to = "super::channel::Column::Id"
+    )]
+    Channel,
+}
+
+impl Related<super::channel::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Channel.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/tables/feature_flag.rs

@@ -0,0 +1,40 @@
+use sea_orm::entity::prelude::*;
+
+use crate::db::FlagId;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "feature_flags")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: FlagId,
+    pub flag: String,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(has_many = "super::user_feature::Entity")]
+    UserFeature,
+}
+
+impl Related<super::user_feature::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::UserFeature.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}
+
+pub struct FlaggedUsers;
+
+impl Linked for FlaggedUsers {
+    type FromEntity = Entity;
+
+    type ToEntity = super::user::Entity;
+
+    fn link(&self) -> Vec<RelationDef> {
+        vec![
+            super::user_feature::Relation::Flag.def().rev(),
+            super::user_feature::Relation::User.def(),
+        ]
+    }
+}

crates/collab/src/db/tables/user.rs

@@ -28,6 +28,8 @@ pub enum Relation {
     HostedProjects,
     #[sea_orm(has_many = "super::channel_member::Entity")]
     ChannelMemberships,
+    #[sea_orm(has_many = "super::user_feature::Entity")]
+    UserFeatures,
 }
 
 impl Related<super::access_token::Entity> for Entity {
@@ -54,4 +56,25 @@ impl Related<super::channel_member::Entity> for Entity {
     }
 }
 
+impl Related<super::user_feature::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::UserFeatures.def()
+    }
+}
+
 impl ActiveModelBehavior for ActiveModel {}
+
+pub struct UserFlags;
+
+impl Linked for UserFlags {
+    type FromEntity = Entity;
+
+    type ToEntity = super::feature_flag::Entity;
+
+    fn link(&self) -> Vec<RelationDef> {
+        vec![
+            super::user_feature::Relation::User.def().rev(),
+            super::user_feature::Relation::Flag.def(),
+        ]
+    }
+}

crates/collab/src/db/tables/user_feature.rs

@@ -0,0 +1,42 @@
+use sea_orm::entity::prelude::*;
+
+use crate::db::{FlagId, UserId};
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "user_features")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub user_id: UserId,
+    #[sea_orm(primary_key)]
+    pub feature_id: FlagId,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(
+        belongs_to = "super::feature_flag::Entity",
+        from = "Column::FeatureId",
+        to = "super::feature_flag::Column::Id"
+    )]
+    Flag,
+    #[sea_orm(
+        belongs_to = "super::user::Entity",
+        from = "Column::UserId",
+        to = "super::user::Column::Id"
+    )]
+    User,
+}
+
+impl Related<super::feature_flag::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Flag.def()
+    }
+}
+
+impl Related<super::user::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::User.def()
+    }
+}
+
+impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/tests.rs

@@ -1,3 +1,7 @@
+mod buffer_tests;
+mod db_tests;
+mod feature_flag_tests;
+
 use super::*;
 use gpui::executor::Background;
 use parking_lot::Mutex;
@@ -91,6 +95,26 @@ impl TestDb {
     }
 }
 
+#[macro_export]
+macro_rules! test_both_dbs {
+    ($test_name:ident, $postgres_test_name:ident, $sqlite_test_name:ident) => {
+        #[gpui::test]
+        async fn $postgres_test_name() {
+            let test_db = crate::db::TestDb::postgres(
+                gpui::executor::Deterministic::new(0).build_background(),
+            );
+            $test_name(test_db.db()).await;
+        }
+
+        #[gpui::test]
+        async fn $sqlite_test_name() {
+            let test_db =
+                crate::db::TestDb::sqlite(gpui::executor::Deterministic::new(0).build_background());
+            $test_name(test_db.db()).await;
+        }
+    };
+}
+
 impl Drop for TestDb {
     fn drop(&mut self) {
         let db = self.db.take().unwrap();

crates/collab/src/db/tests/buffer_tests.rs

@@ -0,0 +1,165 @@
+use super::*;
+use crate::test_both_dbs;
+use language::proto;
+use text::Buffer;
+
+test_both_dbs!(
+    test_channel_buffers,
+    test_channel_buffers_postgres,
+    test_channel_buffers_sqlite
+);
+
+async fn test_channel_buffers(db: &Arc<Database>) {
+    let a_id = db
+        .create_user(
+            "user_a@example.com",
+            false,
+            NewUserParams {
+                github_login: "user_a".into(),
+                github_user_id: 101,
+                invite_count: 0,
+            },
+        )
+        .await
+        .unwrap()
+        .user_id;
+    let b_id = db
+        .create_user(
+            "user_b@example.com",
+            false,
+            NewUserParams {
+                github_login: "user_b".into(),
+                github_user_id: 102,
+                invite_count: 0,
+            },
+        )
+        .await
+        .unwrap()
+        .user_id;
+
+    // This user will not be a part of the channel
+    let c_id = db
+        .create_user(
+            "user_c@example.com",
+            false,
+            NewUserParams {
+                github_login: "user_c".into(),
+                github_user_id: 102,
+                invite_count: 0,
+            },
+        )
+        .await
+        .unwrap()
+        .user_id;
+
+    let owner_id = db.create_server("production").await.unwrap().0 as u32;
+
+    let zed_id = db.create_root_channel("zed", "1", a_id).await.unwrap();
+
+    db.invite_channel_member(zed_id, b_id, a_id, false)
+        .await
+        .unwrap();
+
+    db.respond_to_channel_invite(zed_id, b_id, true)
+        .await
+        .unwrap();
+
+    let connection_id_a = ConnectionId { owner_id, id: 1 };
+    let _ = db
+        .join_channel_buffer(zed_id, a_id, connection_id_a)
+        .await
+        .unwrap();
+
+    let mut buffer_a = Buffer::new(0, 0, "".to_string());
+    let mut operations = Vec::new();
+    operations.push(buffer_a.edit([(0..0, "hello world")]));
+    operations.push(buffer_a.edit([(5..5, ", cruel")]));
+    operations.push(buffer_a.edit([(0..5, "goodbye")]));
+    operations.push(buffer_a.undo().unwrap().1);
+    assert_eq!(buffer_a.text(), "hello, cruel world");
+
+    let operations = operations
+        .into_iter()
+        .map(|op| proto::serialize_operation(&language::Operation::Buffer(op)))
+        .collect::<Vec<_>>();
+
+    db.update_channel_buffer(zed_id, a_id, &operations)
+        .await
+        .unwrap();
+
+    let connection_id_b = ConnectionId { owner_id, id: 2 };
+    let buffer_response_b = db
+        .join_channel_buffer(zed_id, b_id, connection_id_b)
+        .await
+        .unwrap();
+
+    let mut buffer_b = Buffer::new(0, 0, buffer_response_b.base_text);
+    buffer_b
+        .apply_ops(buffer_response_b.operations.into_iter().map(|operation| {
+            let operation = proto::deserialize_operation(operation).unwrap();
+            if let language::Operation::Buffer(operation) = operation {
+                operation
+            } else {
+                unreachable!()
+            }
+        }))
+        .unwrap();
+
+    assert_eq!(buffer_b.text(), "hello, cruel world");
+
+    // Ensure that C fails to open the buffer
+    assert!(db
+        .join_channel_buffer(zed_id, c_id, ConnectionId { owner_id, id: 3 })
+        .await
+        .is_err());
+
+    // Ensure that both collaborators have shown up
+    assert_eq!(
+        buffer_response_b.collaborators,
+        &[
+            rpc::proto::Collaborator {
+                user_id: a_id.to_proto(),
+                peer_id: Some(rpc::proto::PeerId { id: 1, owner_id }),
+                replica_id: 0,
+            },
+            rpc::proto::Collaborator {
+                user_id: b_id.to_proto(),
+                peer_id: Some(rpc::proto::PeerId { id: 2, owner_id }),
+                replica_id: 1,
+            }
+        ]
+    );
+
+    // Ensure that get_channel_buffer_collaborators works
+    let zed_collaborats = db.get_channel_buffer_collaborators(zed_id).await.unwrap();
+    assert_eq!(zed_collaborats, &[a_id, b_id]);
+
+    let collaborators = db
+        .leave_channel_buffer(zed_id, connection_id_b)
+        .await
+        .unwrap();
+
+    assert_eq!(collaborators, &[connection_id_a],);
+
+    let cargo_id = db.create_root_channel("cargo", "2", a_id).await.unwrap();
+    let _ = db
+        .join_channel_buffer(cargo_id, a_id, connection_id_a)
+        .await
+        .unwrap();
+
+    db.leave_channel_buffers(connection_id_a).await.unwrap();
+
+    let zed_collaborators = db.get_channel_buffer_collaborators(zed_id).await.unwrap();
+    let cargo_collaborators = db.get_channel_buffer_collaborators(cargo_id).await.unwrap();
+    assert_eq!(zed_collaborators, &[]);
+    assert_eq!(cargo_collaborators, &[]);
+
+    // When everyone has left the channel, the operations are collapsed into
+    // a new base text.
+    let buffer_response_b = db
+        .join_channel_buffer(zed_id, b_id, connection_id_b)
+        .await
+        .unwrap();
+    assert_eq!(buffer_response_b.base_text, "hello, cruel world");
+    assert_eq!(buffer_response_b.operations, &[]);
+}

crates/collab/src/db/tests/db_tests.rs

@@ -1,32 +1,17 @@
 use super::*;
+use crate::test_both_dbs;
 use gpui::executor::{Background, Deterministic};
 use pretty_assertions::{assert_eq, assert_ne};
 use std::sync::Arc;
-use test_db::TestDb;
-
-macro_rules! test_both_dbs {
-    ($postgres_test_name:ident, $sqlite_test_name:ident, $db:ident, $body:block) => {
-        #[gpui::test]
-        async fn $postgres_test_name() {
-            let test_db = TestDb::postgres(Deterministic::new(0).build_background());
-            let $db = test_db.db();
-            $body
-        }
-
-        #[gpui::test]
-        async fn $sqlite_test_name() {
-            let test_db = TestDb::sqlite(Deterministic::new(0).build_background());
-            let $db = test_db.db();
-            $body
-        }
-    };
-}
+use tests::TestDb;
 
 test_both_dbs!(
+    test_get_users,
     test_get_users_by_ids_postgres,
-    test_get_users_by_ids_sqlite,
-    db,
-    {
+    test_get_users_by_ids_sqlite
+);
+
+async fn test_get_users(db: &Arc<Database>) {
     let mut user_ids = Vec::new();
     let mut user_metric_ids = Vec::new();
     for i in 1..=4 {
@@ -88,13 +73,14 @@ test_both_dbs!(
         ]
     );
 }
-);
 
 test_both_dbs!(
+    test_get_or_create_user_by_github_account,
     test_get_or_create_user_by_github_account_postgres,
-    test_get_or_create_user_by_github_account_sqlite,
-    db,
-    {
+    test_get_or_create_user_by_github_account_sqlite
+);
+
+async fn test_get_or_create_user_by_github_account(db: &Arc<Database>) {
     let user_id1 = db
         .create_user(
             "user1@example.com",
@@ -155,13 +141,14 @@ test_both_dbs!(
     assert_eq!(user.github_user_id, Some(103));
     assert_eq!(user.email_address, Some("user3@example.com".into()));
 }
-);
 
 test_both_dbs!(
+    test_create_access_tokens,
     test_create_access_tokens_postgres,
-    test_create_access_tokens_sqlite,
-    db,
-    {
+    test_create_access_tokens_sqlite
+);
+
+async fn test_create_access_tokens(db: &Arc<Database>) {
     let user = db
         .create_user(
             "u1@example.com",
@@ -234,9 +221,14 @@ test_both_dbs!(
     assert!(db.get_access_token(token_2).await.is_err());
     assert!(db.get_access_token(token_1).await.is_err());
 }
+
+test_both_dbs!(
+    test_add_contacts,
+    test_add_contacts_postgres,
+    test_add_contacts_sqlite
 );
 
-test_both_dbs!(test_add_contacts_postgres, test_add_contacts_sqlite, db, {
+async fn test_add_contacts(db: &Arc<Database>) {
     let mut user_ids = Vec::new();
     for i in 0..3 {
         user_ids.push(
@@ -403,9 +395,15 @@ test_both_dbs!(test_add_contacts_postgres, test_add_contacts_sqlite, db, {
             busy: false,
         }],
     );
-});
+}
 
-test_both_dbs!(test_metrics_id_postgres, test_metrics_id_sqlite, db, {
+test_both_dbs!(
+    test_metrics_id,
+    test_metrics_id_postgres,
+    test_metrics_id_sqlite
+);
+
+async fn test_metrics_id(db: &Arc<Database>) {
     let NewUserResult {
         user_id: user1,
         metrics_id: metrics_id1,
@@ -444,13 +442,15 @@ test_both_dbs!(test_metrics_id_postgres, test_metrics_id_sqlite, db, {
     assert_eq!(metrics_id1.len(), 36);
     assert_eq!(metrics_id2.len(), 36);
     assert_ne!(metrics_id1, metrics_id2);
-});
+}
 
 test_both_dbs!(
+    test_project_count,
     test_project_count_postgres,
-    test_project_count_sqlite,
-    db,
-    {
+    test_project_count_sqlite
+);
+
+async fn test_project_count(db: &Arc<Database>) {
     let owner_id = db.create_server("test").await.unwrap().0 as u32;
 
     let user1 = db
@@ -519,7 +519,6 @@ test_both_dbs!(
         .unwrap();
     assert_eq!(db.project_count_excluding_admins().await.unwrap(), 0);
 }
-);
 
 #[test]
 fn test_fuzzy_like_string() {
@@ -878,7 +877,9 @@ async fn test_invite_codes() {
     assert!(db.has_contact(user5, user1).await.unwrap());
 }
 
-test_both_dbs!(test_channels_postgres, test_channels_sqlite, db, {
+test_both_dbs!(test_channels, test_channels_postgres, test_channels_sqlite);
+
+async fn test_channels(db: &Arc<Database>) {
     let a_id = db
         .create_user(
             "user1@example.com",
@@ -1063,13 +1064,15 @@ test_both_dbs!(test_channels_postgres, test_channels_sqlite, db, {
     assert!(db.get_channel(rust_id, a_id).await.unwrap().is_none());
     assert!(db.get_channel(cargo_id, a_id).await.unwrap().is_none());
     assert!(db.get_channel(cargo_ra_id, a_id).await.unwrap().is_none());
-});
+}
 
 test_both_dbs!(
+    test_joining_channels,
     test_joining_channels_postgres,
-    test_joining_channels_sqlite,
-    db,
-    {
+    test_joining_channels_sqlite
+);
+
+async fn test_joining_channels(db: &Arc<Database>) {
     let owner_id = db.create_server("test").await.unwrap().0 as u32;
 
     let user_1 = db
@@ -1119,13 +1122,14 @@ test_both_dbs!(
         .await
         .is_err());
 }
-);
 
 test_both_dbs!(
+    test_channel_invites,
     test_channel_invites_postgres,
-    test_channel_invites_sqlite,
-    db,
-    {
+    test_channel_invites_sqlite
+);
+
+async fn test_channel_invites(db: &Arc<Database>) {
     db.create_server("test").await.unwrap();
 
     let user_1 = db
@@ -1263,13 +1267,14 @@ test_both_dbs!(
         ]
     );
 }
-);
 
 test_both_dbs!(
+    test_channel_renames,
     test_channel_renames_postgres,
-    test_channel_renames_sqlite,
-    db,
-    {
+    test_channel_renames_sqlite
+);
+
+async fn test_channel_renames(db: &Arc<Database>) {
     db.create_server("test").await.unwrap();
 
     let user_1 = db
@@ -1323,7 +1328,6 @@ test_both_dbs!(
     let bad_name_rename = db.rename_channel(zed_id, user_1, "#").await;
     assert!(bad_name_rename.is_err())
 }
-);
 
 #[gpui::test]
 async fn test_multiple_signup_overwrite() {

crates/collab/src/db/tests/feature_flag_tests.rs

@@ -0,0 +1,60 @@
+use crate::{
+    db::{Database, NewUserParams},
+    test_both_dbs,
+};
+use std::sync::Arc;
+
+test_both_dbs!(
+    test_get_user_flags,
+    test_get_user_flags_postgres,
+    test_get_user_flags_sqlite
+);
+
+async fn test_get_user_flags(db: &Arc<Database>) {
+    let user_1 = db
+        .create_user(
+            &format!("user1@example.com"),
+            false,
+            NewUserParams {
+                github_login: format!("user1"),
+                github_user_id: 1,
+                invite_count: 0,
+            },
+        )
+        .await
+        .unwrap()
+        .user_id;
+
+    let user_2 = db
+        .create_user(
+            &format!("user2@example.com"),
+            false,
+            NewUserParams {
+                github_login: format!("user2"),
+                github_user_id: 2,
+                invite_count: 0,
+            },
+        )
+        .await
+        .unwrap()
+        .user_id;
+
+    const CHANNELS_ALPHA: &'static str = "channels-alpha";
+    const NEW_SEARCH: &'static str = "new-search";
+
+    let channels_flag = db.create_user_flag(CHANNELS_ALPHA).await.unwrap();
+    let search_flag = db.create_user_flag(NEW_SEARCH).await.unwrap();
+
+    db.add_user_flag(user_1, channels_flag).await.unwrap();
+    db.add_user_flag(user_1, search_flag).await.unwrap();
+
+    db.add_user_flag(user_2, channels_flag).await.unwrap();
+
+    let mut user_1_flags = db.get_user_flags(user_1).await.unwrap();
+    user_1_flags.sort();
+    assert_eq!(user_1_flags, &[CHANNELS_ALPHA, NEW_SEARCH]);
+
+    let mut user_2_flags = db.get_user_flags(user_2).await.unwrap();
+    user_2_flags.sort();
+    assert_eq!(user_2_flags, &[CHANNELS_ALPHA]);
+}

crates/collab/src/rpc.rs

@@ -35,8 +35,8 @@ use lazy_static::lazy_static;
 use prometheus::{register_int_gauge, IntGauge};
 use rpc::{
     proto::{
-        self, AnyTypedEnvelope, EntityMessage, EnvelopedMessage, LiveKitConnectionInfo,
-        RequestMessage,
+        self, Ack, AddChannelBufferCollaborator, AnyTypedEnvelope, EntityMessage, EnvelopedMessage,
+        LiveKitConnectionInfo, RequestMessage,
     },
     Connection, ConnectionId, Peer, Receipt, TypedEnvelope,
 };
@@ -248,6 +248,9 @@ impl Server {
             .add_request_handler(remove_channel_member)
             .add_request_handler(set_channel_member_admin)
             .add_request_handler(rename_channel)
+            .add_request_handler(join_channel_buffer)
+            .add_request_handler(leave_channel_buffer)
+            .add_message_handler(update_channel_buffer)
             .add_request_handler(get_channel_members)
             .add_request_handler(respond_to_channel_invite)
             .add_request_handler(join_channel)
@@ -851,6 +854,10 @@ async fn connection_lost(
         .await
         .trace_err();
 
+    leave_channel_buffers_for_session(&session)
+        .await
+        .trace_err();
+
     futures::select_biased! {
         _ = executor.sleep(RECONNECT_TIMEOUT).fuse() => {
             leave_room_for_session(&session).await.trace_err();
@@ -866,6 +873,8 @@ async fn connection_lost(
                 }
             }
             update_user_contacts(session.user_id, &session).await?;
+
+
         }
         _ = teardown.changed().fuse() => {}
     }
@@ -2478,6 +2487,104 @@ async fn join_channel(
     Ok(())
 }
 
+async fn join_channel_buffer(
+    request: proto::JoinChannelBuffer,
+    response: Response<proto::JoinChannelBuffer>,
+    session: Session,
+) -> Result<()> {
+    let db = session.db().await;
+    let channel_id = ChannelId::from_proto(request.channel_id);
+
+    let open_response = db
+        .join_channel_buffer(channel_id, session.user_id, session.connection_id)
+        .await?;
+
+    let replica_id = open_response.replica_id;
+    let collaborators = open_response.collaborators.clone();
+
+    response.send(open_response)?;
+
+    let update = AddChannelBufferCollaborator {
+        channel_id: channel_id.to_proto(),
+        collaborator: Some(proto::Collaborator {
+            user_id: session.user_id.to_proto(),
+            peer_id: Some(session.connection_id.into()),
+            replica_id,
+        }),
+    };
+    channel_buffer_updated(
+        session.connection_id,
+        collaborators
+            .iter()
+            .filter_map(|collaborator| Some(collaborator.peer_id?.into())),
+        &update,
+        &session.peer,
+    );
+
+    Ok(())
+}
+
+async fn update_channel_buffer(
+    request: proto::UpdateChannelBuffer,
+    session: Session,
+) -> Result<()> {
+    let db = session.db().await;
+    let channel_id = ChannelId::from_proto(request.channel_id);
+
+    let collaborators = db
+        .update_channel_buffer(channel_id, session.user_id, &request.operations)
+        .await?;
+
+    channel_buffer_updated(
+        session.connection_id,
+        collaborators,
+        &proto::UpdateChannelBuffer {
+            channel_id: channel_id.to_proto(),
+            operations: request.operations,
+        },
+        &session.peer,
+    );
+    Ok(())
+}
+
+async fn leave_channel_buffer(
+    request: proto::LeaveChannelBuffer,
+    response: Response<proto::LeaveChannelBuffer>,
+    session: Session,
+) -> Result<()> {
+    let db = session.db().await;
+    let channel_id = ChannelId::from_proto(request.channel_id);
+
+    let collaborators_to_notify = db
+        .leave_channel_buffer(channel_id, session.connection_id)
+        .await?;
+
+    response.send(Ack {})?;
+
+    channel_buffer_updated(
+        session.connection_id,
+        collaborators_to_notify,
+        &proto::RemoveChannelBufferCollaborator {
+            channel_id: channel_id.to_proto(),
+            peer_id: Some(session.connection_id.into()),
+        },
+        &session.peer,
+    );
+
+    Ok(())
+}
+
+fn channel_buffer_updated<T: EnvelopedMessage>(
+    sender_id: ConnectionId,
+    collaborators: impl IntoIterator<Item = ConnectionId>,
+    message: &T,
+    peer: &Peer,
+) {
+    broadcast(Some(sender_id), collaborators.into_iter(), |peer_id| {
+        peer.send(peer_id.into(), message.clone())
+    });
+}
+
 async fn update_diff_base(request: proto::UpdateDiffBase, session: Session) -> Result<()> {
     let project_id = ProjectId::from_proto(request.project_id);
     let project_connection_ids = session
@@ -2502,20 +2609,19 @@ async fn get_private_user_info(
     response: Response<proto::GetPrivateUserInfo>,
     session: Session,
 ) -> Result<()> {
-    let metrics_id = session
-        .db()
-        .await
-        .get_user_metrics_id(session.user_id)
-        .await?;
-    let user = session
-        .db()
-        .await
+    let db = session.db().await;
+
+    let metrics_id = db.get_user_metrics_id(session.user_id).await?;
+    let user = db
         .get_user_by_id(session.user_id)
         .await?
         .ok_or_else(|| anyhow!("user not found"))?;
+    let flags = db.get_user_flags(session.user_id).await?;
+
     response.send(proto::GetPrivateUserInfoResponse {
         metrics_id,
         staff: user.admin,
+        flags,
     })?;
     Ok(())
 }
@@ -2803,6 +2909,28 @@ async fn leave_room_for_session(session: &Session) -> Result<()> {
     Ok(())
 }
 
+async fn leave_channel_buffers_for_session(session: &Session) -> Result<()> {
+    let left_channel_buffers = session
+        .db()
+        .await
+        .leave_channel_buffers(session.connection_id)
+        .await?;
+
+    for (channel_id, connections) in left_channel_buffers {
+        channel_buffer_updated(
+            session.connection_id,
+            connections,
+            &proto::RemoveChannelBufferCollaborator {
+                channel_id: channel_id.to_proto(),
+                peer_id: Some(session.connection_id.into()),
+            },
+            &session.peer,
+        );
+    }
+
+    Ok(())
+}
+
 fn project_left(project: &db::LeftProject, session: &Session) {
     for connection_id in &project.connection_ids {
         if project.host_user_id == session.user_id {

crates/collab/src/tests.rs

@@ -1,14 +1,14 @@
 use crate::{
-    db::{test_db::TestDb, NewUserParams, UserId},
+    db::{tests::TestDb, NewUserParams, UserId},
     executor::Executor,
     rpc::{Server, CLEANUP_TIMEOUT},
     AppState,
 };
 use anyhow::anyhow;
 use call::{ActiveCall, Room};
+use channel::ChannelStore;
 use client::{
-    self, proto::PeerId, ChannelStore, Client, Connection, Credentials, EstablishConnectionError,
-    UserStore,
+    self, proto::PeerId, Client, Connection, Credentials, EstablishConnectionError, UserStore,
 };
 use collections::{HashMap, HashSet};
 use fs::FakeFs;
@@ -31,6 +31,7 @@ use std::{
 use util::http::FakeHttpClient;
 use workspace::Workspace;
 
+mod channel_buffer_tests;
 mod channel_tests;
 mod integration_tests;
 mod randomized_integration_tests;
@@ -210,6 +211,7 @@ impl TestServer {
             workspace::init(app_state.clone(), cx);
             audio::init((), cx);
             call::init(client.clone(), user_store.clone(), cx);
+            channel::init(&client);
         });
 
         client

crates/collab/src/tests/channel_buffer_tests.rs

@@ -0,0 +1,426 @@
+use crate::{rpc::RECONNECT_TIMEOUT, tests::TestServer};
+use call::ActiveCall;
+use channel::Channel;
+use client::UserId;
+use collab_ui::channel_view::ChannelView;
+use collections::HashMap;
+use futures::future;
+use gpui::{executor::Deterministic, ModelHandle, TestAppContext};
+use rpc::{proto, RECEIVE_TIMEOUT};
+use serde_json::json;
+use std::sync::Arc;
+
+#[gpui::test]
+async fn test_core_channel_buffers(
+    deterministic: Arc<Deterministic>,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+) {
+    deterministic.forbid_parking();
+    let mut server = TestServer::start(&deterministic).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+
+    let zed_id = server
+        .make_channel("zed", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .await;
+
+    // Client A joins the channel buffer
+    let channel_buffer_a = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| channel.open_channel_buffer(zed_id, cx))
+        .await
+        .unwrap();
+
+    // Client A edits the buffer
+    let buffer_a = channel_buffer_a.read_with(cx_a, |buffer, _| buffer.buffer());
+
+    buffer_a.update(cx_a, |buffer, cx| {
+        buffer.edit([(0..0, "hello world")], None, cx)
+    });
+    buffer_a.update(cx_a, |buffer, cx| {
+        buffer.edit([(5..5, ", cruel")], None, cx)
+    });
+    buffer_a.update(cx_a, |buffer, cx| {
+        buffer.edit([(0..5, "goodbye")], None, cx)
+    });
+    buffer_a.update(cx_a, |buffer, cx| buffer.undo(cx));
+    deterministic.run_until_parked();
+
+    assert_eq!(buffer_text(&buffer_a, cx_a), "hello, cruel world");
+
+    // Client B joins the channel buffer
+    let channel_buffer_b = client_b
+        .channel_store()
+        .update(cx_b, |channel, cx| channel.open_channel_buffer(zed_id, cx))
+        .await
+        .unwrap();
+
+    channel_buffer_b.read_with(cx_b, |buffer, _| {
+        assert_collaborators(
+            buffer.collaborators(),
+            &[client_a.user_id(), client_b.user_id()],
+        );
+    });
+
+    // Client B sees the correct text, and then edits it
+    let buffer_b = channel_buffer_b.read_with(cx_b, |buffer, _| buffer.buffer());
+    assert_eq!(
+        buffer_b.read_with(cx_b, |buffer, _| buffer.remote_id()),
+        buffer_a.read_with(cx_a, |buffer, _| buffer.remote_id())
+    );
+    assert_eq!(buffer_text(&buffer_b, cx_b), "hello, cruel world");
+    buffer_b.update(cx_b, |buffer, cx| {
+        buffer.edit([(7..12, "beautiful")], None, cx)
+    });
+
+    // Both A and B see the new edit
+    deterministic.run_until_parked();
+    assert_eq!(buffer_text(&buffer_a, cx_a), "hello, beautiful world");
+    assert_eq!(buffer_text(&buffer_b, cx_b), "hello, beautiful world");
+
+    // Client A closes the channel buffer.
+    cx_a.update(|_| drop(channel_buffer_a));
+    deterministic.run_until_parked();
+
+    // Client B sees that client A is gone from the channel buffer.
+    channel_buffer_b.read_with(cx_b, |buffer, _| {
+        assert_collaborators(&buffer.collaborators(), &[client_b.user_id()]);
+    });
+
+    // Client A rejoins the channel buffer
+    let _channel_buffer_a = client_a
+        .channel_store()
+        .update(cx_a, |channels, cx| {
+            channels.open_channel_buffer(zed_id, cx)
+        })
+        .await
+        .unwrap();
+    deterministic.run_until_parked();
+
+    // Sanity test, make sure we saw A rejoining
+    channel_buffer_b.read_with(cx_b, |buffer, _| {
+        assert_collaborators(
+            &buffer.collaborators(),
+            &[client_b.user_id(), client_a.user_id()],
+        );
+    });
+
+    // Client A loses connection.
+    server.forbid_connections();
+    server.disconnect_client(client_a.peer_id().unwrap());
+    deterministic.advance_clock(RECEIVE_TIMEOUT + RECONNECT_TIMEOUT);
+
+    // Client B observes A disconnect
+    channel_buffer_b.read_with(cx_b, |buffer, _| {
+        assert_collaborators(&buffer.collaborators(), &[client_b.user_id()]);
+    });
+
+    // TODO:
+    // - Test synchronizing offline updates, what happens to A's channel buffer when A disconnects
+    // - Test interaction with channel deletion while buffer is open
+}
+
+#[gpui::test]
+async fn test_channel_buffer_replica_ids(
+    deterministic: Arc<Deterministic>,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+    cx_c: &mut TestAppContext,
+) {
+    deterministic.forbid_parking();
+    let mut server = TestServer::start(&deterministic).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+    let client_c = server.create_client(cx_c, "user_c").await;
+
+    let channel_id = server
+        .make_channel(
+            "zed",
+            (&client_a, cx_a),
+            &mut [(&client_b, cx_b), (&client_c, cx_c)],
+        )
+        .await;
+
+    let active_call_a = cx_a.read(ActiveCall::global);
+    let active_call_b = cx_b.read(ActiveCall::global);
+    let active_call_c = cx_c.read(ActiveCall::global);
+
+    // Clients A and B join a channel.
+    active_call_a
+        .update(cx_a, |call, cx| call.join_channel(channel_id, cx))
+        .await
+        .unwrap();
+    active_call_b
+        .update(cx_b, |call, cx| call.join_channel(channel_id, cx))
+        .await
+        .unwrap();
+
+    // Clients A, B, and C join a channel buffer
+    // C first so that the replica IDs in the project and the channel buffer are different
+    let channel_buffer_c = client_c
+        .channel_store()
+        .update(cx_c, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+    let channel_buffer_b = client_b
+        .channel_store()
+        .update(cx_b, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+    let channel_buffer_a = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+
+    // Client B shares a project
+    client_b
+        .fs()
+        .insert_tree("/dir", json!({ "file.txt": "contents" }))
+        .await;
+    let (project_b, _) = client_b.build_local_project("/dir", cx_b).await;
+    let shared_project_id = active_call_b
+        .update(cx_b, |call, cx| call.share_project(project_b.clone(), cx))
+        .await
+        .unwrap();
+
+    // Client A joins the project
+    let project_a = client_a.build_remote_project(shared_project_id, cx_a).await;
+    deterministic.run_until_parked();
+
+    // Client C is in a separate project.
+    client_c.fs().insert_tree("/dir", json!({})).await;
+    let (separate_project_c, _) = client_c.build_local_project("/dir", cx_c).await;
+
+    // Note that each user has a different replica id in the projects vs the
+    // channel buffer.
+    channel_buffer_a.read_with(cx_a, |channel_buffer, cx| {
+        assert_eq!(project_a.read(cx).replica_id(), 1);
+        assert_eq!(channel_buffer.buffer().read(cx).replica_id(), 2);
+    });
+    channel_buffer_b.read_with(cx_b, |channel_buffer, cx| {
+        assert_eq!(project_b.read(cx).replica_id(), 0);
+        assert_eq!(channel_buffer.buffer().read(cx).replica_id(), 1);
+    });
+    channel_buffer_c.read_with(cx_c, |channel_buffer, cx| {
+        // C is not in the project
+        assert_eq!(channel_buffer.buffer().read(cx).replica_id(), 0);
+    });
+
+    let channel_window_a =
+        cx_a.add_window(|cx| ChannelView::new(project_a.clone(), channel_buffer_a.clone(), cx));
+    let channel_window_b =
+        cx_b.add_window(|cx| ChannelView::new(project_b.clone(), channel_buffer_b.clone(), cx));
+    let channel_window_c = cx_c.add_window(|cx| {
+        ChannelView::new(separate_project_c.clone(), channel_buffer_c.clone(), cx)
+    });
+
+    let channel_view_a = channel_window_a.root(cx_a);
+    let channel_view_b = channel_window_b.root(cx_b);
+    let channel_view_c = channel_window_c.root(cx_c);
+
+    // For clients A and B, the replica ids in the channel buffer are mapped
+    // so that they match the same users' replica ids in their shared project.
+    channel_view_a.read_with(cx_a, |view, cx| {
+        assert_eq!(
+            view.editor.read(cx).replica_id_map().unwrap(),
+            &[(1, 0), (2, 1)].into_iter().collect::<HashMap<_, _>>()
+        );
+    });
+    channel_view_b.read_with(cx_b, |view, cx| {
+        assert_eq!(
+            view.editor.read(cx).replica_id_map().unwrap(),
+            &[(1, 0), (2, 1)].into_iter().collect::<HashMap<u16, u16>>(),
+        )
+    });
+
+    // Client C only sees themself, as they're not part of any shared project
+    channel_view_c.read_with(cx_c, |view, cx| {
+        assert_eq!(
+            view.editor.read(cx).replica_id_map().unwrap(),
+            &[(0, 0)].into_iter().collect::<HashMap<u16, u16>>(),
+        );
+    });
+
+    // Client C joins the project that clients A and B are in.
+    active_call_c
+        .update(cx_c, |call, cx| call.join_channel(channel_id, cx))
+        .await
+        .unwrap();
+    let project_c = client_c.build_remote_project(shared_project_id, cx_c).await;
+    deterministic.run_until_parked();
+    project_c.read_with(cx_c, |project, _| {
+        assert_eq!(project.replica_id(), 2);
+    });
+
+    // For clients A and B, client C's replica id in the channel buffer is
+    // now mapped to their replica id in the shared project.
+    channel_view_a.read_with(cx_a, |view, cx| {
+        assert_eq!(
+            view.editor.read(cx).replica_id_map().unwrap(),
+            &[(1, 0), (2, 1), (0, 2)]
+                .into_iter()
+                .collect::<HashMap<_, _>>()
+        );
+    });
+    channel_view_b.read_with(cx_b, |view, cx| {
+        assert_eq!(
+            view.editor.read(cx).replica_id_map().unwrap(),
+            &[(1, 0), (2, 1), (0, 2)]
+                .into_iter()
+                .collect::<HashMap<_, _>>(),
+        )
+    });
+}
+
+#[gpui::test]
+async fn test_reopen_channel_buffer(deterministic: Arc<Deterministic>, cx_a: &mut TestAppContext) {
+    deterministic.forbid_parking();
+    let mut server = TestServer::start(&deterministic).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+
+    let zed_id = server.make_channel("zed", (&client_a, cx_a), &mut []).await;
+
+    let channel_buffer_1 = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| channel.open_channel_buffer(zed_id, cx));
+    let channel_buffer_2 = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| channel.open_channel_buffer(zed_id, cx));
+    let channel_buffer_3 = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| channel.open_channel_buffer(zed_id, cx));
+
+    // All concurrent tasks for opening a channel buffer return the same model handle.
+    let (channel_buffer_1, channel_buffer_2, channel_buffer_3) =
+        future::try_join3(channel_buffer_1, channel_buffer_2, channel_buffer_3)
+            .await
+            .unwrap();
+    let model_id = channel_buffer_1.id();
+    assert_eq!(channel_buffer_1, channel_buffer_2);
+    assert_eq!(channel_buffer_1, channel_buffer_3);
+
+    channel_buffer_1.update(cx_a, |buffer, cx| {
+        buffer.buffer().update(cx, |buffer, cx| {
+            buffer.edit([(0..0, "hello")], None, cx);
+        })
+    });
+    deterministic.run_until_parked();
+
+    cx_a.update(|_| {
+        drop(channel_buffer_1);
+        drop(channel_buffer_2);
+        drop(channel_buffer_3);
+    });
+    deterministic.run_until_parked();
+
+    // The channel buffer can be reopened after dropping it.
+    let channel_buffer = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| channel.open_channel_buffer(zed_id, cx))
+        .await
+        .unwrap();
+    assert_ne!(channel_buffer.id(), model_id);
+    channel_buffer.update(cx_a, |buffer, cx| {
+        buffer.buffer().update(cx, |buffer, _| {
+            assert_eq!(buffer.text(), "hello");
+        })
+    });
+}
+
+#[gpui::test]
+async fn test_channel_buffer_disconnect(
+    deterministic: Arc<Deterministic>,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+) {
+    deterministic.forbid_parking();
+    let mut server = TestServer::start(&deterministic).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+
+    let channel_id = server
+        .make_channel("zed", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .await;
+
+    let channel_buffer_a = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+
+    let channel_buffer_b = client_b
+        .channel_store()
+        .update(cx_b, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+
+    server.forbid_connections();
+    server.disconnect_client(client_a.peer_id().unwrap());
+    deterministic.advance_clock(RECEIVE_TIMEOUT + RECONNECT_TIMEOUT);
+
+    channel_buffer_a.update(cx_a, |buffer, _| {
+        assert_eq!(
+            buffer.channel().as_ref(),
+            &Channel {
+                id: channel_id,
+                name: "zed".to_string()
+            }
+        );
+        assert!(!buffer.is_connected());
+    });
+
+    deterministic.run_until_parked();
+
+    server.allow_connections();
+    deterministic.advance_clock(RECEIVE_TIMEOUT + RECONNECT_TIMEOUT);
+
+    deterministic.run_until_parked();
+
+    client_a
+        .channel_store()
+        .update(cx_a, |channel_store, _| {
+            channel_store.remove_channel(channel_id)
+        })
+        .await
+        .unwrap();
+    deterministic.run_until_parked();
+
+    // Channel buffer observed the deletion
+    channel_buffer_b.update(cx_b, |buffer, _| {
+        assert_eq!(
+            buffer.channel().as_ref(),
+            &Channel {
+                id: channel_id,
+                name: "zed".to_string()
+            }
+        );
+        assert!(!buffer.is_connected());
+    });
+}
+
+#[track_caller]
+fn assert_collaborators(collaborators: &[proto::Collaborator], ids: &[Option<UserId>]) {
+    assert_eq!(
+        collaborators
+            .into_iter()
+            .map(|collaborator| collaborator.user_id)
+            .collect::<Vec<_>>(),
+        ids.into_iter().map(|id| id.unwrap()).collect::<Vec<_>>()
+    );
+}
+
+fn buffer_text(channel_buffer: &ModelHandle<language::Buffer>, cx: &mut TestAppContext) -> String {
+    channel_buffer.read_with(cx, |buffer, _| buffer.text())
+}

crates/collab/src/tests/channel_tests.rs

@@ -3,7 +3,8 @@ use crate::{
     tests::{room_participants, RoomParticipants, TestServer},
 };
 use call::ActiveCall;
-use client::{ChannelId, ChannelMembership, ChannelStore, User};
+use channel::{ChannelId, ChannelMembership, ChannelStore};
+use client::User;
 use gpui::{executor::Deterministic, ModelHandle, TestAppContext};
 use rpc::{proto, RECEIVE_TIMEOUT};
 use std::sync::Arc;
@@ -798,7 +799,7 @@ async fn test_lost_channel_creation(
 
     deterministic.run_until_parked();
 
-    // Sanity check
+    // Sanity check, B has the invitation
     assert_channel_invitations(
         client_b.channel_store(),
         cx_b,
@@ -810,6 +811,7 @@ async fn test_lost_channel_creation(
         }],
     );
 
+    // A creates a subchannel while the invite is still pending.
     let subchannel_id = client_a
         .channel_store()
         .update(cx_a, |channel_store, cx| {
@@ -840,7 +842,7 @@ async fn test_lost_channel_creation(
         ],
     );
 
-    // Accept the invite
+    // Client B accepts the invite
     client_b
         .channel_store()
         .update(cx_b, |channel_store, _| {
@@ -851,7 +853,7 @@ async fn test_lost_channel_creation(
 
     deterministic.run_until_parked();
 
-    // B should now see the channel
+    // Client B should now see the channel
     assert_channels(
         client_b.channel_store(),
         cx_b,

crates/collab/src/tests/integration_tests.rs

@@ -4,7 +4,7 @@ use crate::{
 };
 use call::{room, ActiveCall, ParticipantLocation, Room};
 use client::{User, RECEIVE_TIMEOUT};
-use collections::HashSet;
+use collections::{HashMap, HashSet};
 use editor::{
     test::editor_test_context::EditorTestContext, ConfirmCodeAction, ConfirmCompletion,
     ConfirmRename, Editor, ExcerptRange, MultiBuffer, Redo, Rename, ToggleCodeActions, Undo,
@@ -4821,15 +4821,16 @@ async fn test_project_search(
     let project_b = client_b.build_remote_project(project_id, cx_b).await;
 
     // Perform a search as the guest.
-    let results = project_b
-        .update(cx_b, |project, cx| {
+    let mut results = HashMap::default();
+    let mut search_rx = project_b.update(cx_b, |project, cx| {
         project.search(
             SearchQuery::text("world", false, false, Vec::new(), Vec::new()),
             cx,
         )
-        })
-        .await
-        .unwrap();
+    });
+    while let Some((buffer, ranges)) = search_rx.next().await {
+        results.entry(buffer).or_insert(ranges);
+    }
 
     let mut ranges_by_path = results
         .into_iter()
@@ -5320,7 +5321,7 @@ async fn test_collaborating_with_code_actions(
         .unwrap();
 
     let mut fake_language_server = fake_language_servers.next().await.unwrap();
-    fake_language_server
+    let mut requests = fake_language_server
         .handle_request::<lsp::request::CodeActionRequest, _, _>(|params, _| async move {
             assert_eq!(
                 params.text_document.uri,
@@ -5329,9 +5330,9 @@ async fn test_collaborating_with_code_actions(
             assert_eq!(params.range.start, lsp::Position::new(0, 0));
             assert_eq!(params.range.end, lsp::Position::new(0, 0));
             Ok(None)
-        })
-        .next()
-        .await;
+        });
+    deterministic.advance_clock(editor::CODE_ACTIONS_DEBOUNCE_TIMEOUT * 2);
+    requests.next().await;
 
     // Move cursor to a location that contains code actions.
     editor_b.update(cx_b, |editor, cx| {
@@ -5341,7 +5342,7 @@ async fn test_collaborating_with_code_actions(
         cx.focus(&editor_b);
     });
 
-    fake_language_server
+    let mut requests = fake_language_server
         .handle_request::<lsp::request::CodeActionRequest, _, _>(|params, _| async move {
             assert_eq!(
                 params.text_document.uri,
@@ -5393,9 +5394,9 @@ async fn test_collaborating_with_code_actions(
                     ..Default::default()
                 },
             )]))
-        })
-        .next()
-        .await;
+        });
+    deterministic.advance_clock(editor::CODE_ACTIONS_DEBOUNCE_TIMEOUT * 2);
+    requests.next().await;
 
     // Toggle code actions and wait for them to display.
     editor_b.update(cx_b, |editor, cx| {
@@ -7863,6 +7864,7 @@ async fn test_mutual_editor_inlay_hint_cache_update(
     client_a.language_registry().add(Arc::clone(&language));
     client_b.language_registry().add(language);
 
+    // Client A opens a project.
     client_a
         .fs()
         .insert_tree(
@@ -7883,6 +7885,7 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         .await
         .unwrap();
 
+    // Client B joins the project
     let project_b = client_b.build_remote_project(project_id, cx_b).await;
     active_call_b
         .update(cx_b, |call, cx| call.set_location(Some(&project_b), cx))
@@ -7892,6 +7895,7 @@ async fn test_mutual_editor_inlay_hint_cache_update(
     let workspace_a = client_a.build_workspace(&project_a, cx_a).root(cx_a);
     cx_a.foreground().start_waiting();
 
+    // The host opens a rust file.
     let _buffer_a = project_a
         .update(cx_a, |project, cx| {
             project.open_local_buffer("/a/main.rs", cx)
@@ -7899,7 +7903,6 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         .await
         .unwrap();
     let fake_language_server = fake_language_servers.next().await.unwrap();
-    let next_call_id = Arc::new(AtomicU32::new(0));
     let editor_a = workspace_a
         .update(cx_a, |workspace, cx| {
             workspace.open_path((worktree_id, "main.rs"), None, true, cx)
@@ -7908,6 +7911,9 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         .unwrap()
         .downcast::<Editor>()
         .unwrap();
+
+    // Set up the language server to return an additional inlay hint on each request.
+    let next_call_id = Arc::new(AtomicU32::new(0));
     fake_language_server
         .handle_request::<lsp::request::InlayHintRequest, _, _>(move |params, _| {
             let task_next_call_id = Arc::clone(&next_call_id);
@@ -7916,33 +7922,28 @@ async fn test_mutual_editor_inlay_hint_cache_update(
                     params.text_document.uri,
                     lsp::Url::from_file_path("/a/main.rs").unwrap(),
                 );
-                let mut current_call_id = Arc::clone(&task_next_call_id).fetch_add(1, SeqCst);
-                let mut new_hints = Vec::with_capacity(current_call_id as usize);
-                loop {
-                    new_hints.push(lsp::InlayHint {
-                        position: lsp::Position::new(0, current_call_id),
-                        label: lsp::InlayHintLabel::String(current_call_id.to_string()),
+                let call_count = task_next_call_id.fetch_add(1, SeqCst);
+                Ok(Some(
+                    (0..=call_count)
+                        .map(|ix| lsp::InlayHint {
+                            position: lsp::Position::new(0, ix),
+                            label: lsp::InlayHintLabel::String(ix.to_string()),
                             kind: None,
                             text_edits: None,
                             tooltip: None,
                             padding_left: None,
                             padding_right: None,
                             data: None,
-                    });
-                    if current_call_id == 0 {
-                        break;
-                    }
-                    current_call_id -= 1;
-                }
-                Ok(Some(new_hints))
+                        })
+                        .collect(),
+                ))
             }
         })
         .next()
         .await
         .unwrap();
 
-    cx_a.foreground().finish_waiting();
-    cx_a.foreground().run_until_parked();
+    deterministic.run_until_parked();
 
     let mut edits_made = 1;
     editor_a.update(cx_a, |editor, _| {
@@ -7968,7 +7969,7 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         .downcast::<Editor>()
         .unwrap();
 
-    cx_b.foreground().run_until_parked();
+    deterministic.run_until_parked();
     editor_b.update(cx_b, |editor, _| {
         assert_eq!(
             vec!["0".to_string(), "1".to_string()],
@@ -7989,18 +7990,9 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         cx.focus(&editor_b);
         edits_made += 1;
     });
-    cx_a.foreground().run_until_parked();
-    cx_b.foreground().run_until_parked();
+
+    deterministic.run_until_parked();
     editor_a.update(cx_a, |editor, _| {
-        assert_eq!(
-            vec!["0".to_string(), "1".to_string(), "2".to_string()],
-            extract_hint_labels(editor),
-            "Host should get hints from the 1st edit and 1st LSP query"
-        );
-        let inlay_cache = editor.inlay_hint_cache();
-        assert_eq!(inlay_cache.version(), edits_made);
-    });
-    editor_b.update(cx_b, |editor, _| {
         assert_eq!(
             vec![
                 "0".to_string(),
@@ -8014,6 +8006,15 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         let inlay_cache = editor.inlay_hint_cache();
         assert_eq!(inlay_cache.version(), edits_made);
     });
+    editor_b.update(cx_b, |editor, _| {
+        assert_eq!(
+            vec!["0".to_string(), "1".to_string(), "2".to_string(),],
+            extract_hint_labels(editor),
+            "Guest should get hints the 1st edit and 2nd LSP query"
+        );
+        let inlay_cache = editor.inlay_hint_cache();
+        assert_eq!(inlay_cache.version(), edits_made);
+    });
 
     editor_a.update(cx_a, |editor, cx| {
         editor.change_selections(None, cx, |s| s.select_ranges([13..13]));
@@ -8021,8 +8022,8 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         cx.focus(&editor_a);
         edits_made += 1;
     });
-    cx_a.foreground().run_until_parked();
-    cx_b.foreground().run_until_parked();
+
+    deterministic.run_until_parked();
     editor_a.update(cx_a, |editor, _| {
         assert_eq!(
             vec![
@@ -8061,8 +8062,8 @@ async fn test_mutual_editor_inlay_hint_cache_update(
         .await
         .expect("inlay refresh request failed");
     edits_made += 1;
-    cx_a.foreground().run_until_parked();
-    cx_b.foreground().run_until_parked();
+
+    deterministic.run_until_parked();
     editor_a.update(cx_a, |editor, _| {
         assert_eq!(
             vec![

crates/collab/src/tests/randomized_integration_tests.rs

@@ -6,7 +6,7 @@ use crate::{
 use anyhow::{anyhow, Result};
 use call::ActiveCall;
 use client::RECEIVE_TIMEOUT;
-use collections::BTreeMap;
+use collections::{BTreeMap, HashMap};
 use editor::Bias;
 use fs::{repository::GitFileStatus, FakeFs, Fs as _};
 use futures::StreamExt as _;
@@ -121,7 +121,9 @@ async fn test_random_collaboration(
     let mut operation_channels = Vec::new();
 
     loop {
-        let Some((next_operation, applied)) = plan.lock().next_server_operation(&clients) else { break };
+        let Some((next_operation, applied)) = plan.lock().next_server_operation(&clients) else {
+            break;
+        };
         applied.store(true, SeqCst);
         let did_apply = apply_server_operation(
             deterministic.clone(),
@@ -224,7 +226,9 @@ async fn apply_server_operation(
             let client_ix = clients
                 .iter()
                 .position(|(client, cx)| client.current_user_id(cx) == removed_user_id);
-            let Some(client_ix) = client_ix else { return false };
+            let Some(client_ix) = client_ix else {
+                return false;
+            };
             let user_connection_ids = server
                 .connection_pool
                 .lock()
@@ -718,7 +722,7 @@ async fn apply_client_operation(
                 if detach { "detaching" } else { "awaiting" }
             );
 
-            let search = project.update(cx, |project, cx| {
+            let mut search = project.update(cx, |project, cx| {
                 project.search(
                     SearchQuery::text(query, false, false, Vec::new(), Vec::new()),
                     cx,
@@ -726,15 +730,13 @@ async fn apply_client_operation(
             });
             drop(project);
             let search = cx.background().spawn(async move {
-                search
-                    .await
-                    .map_err(|err| anyhow!("search request failed: {:?}", err))
-            });
-            if detach {
-                cx.update(|cx| search.detach_and_log_err(cx));
-            } else {
-                search.await?;
+                let mut results = HashMap::default();
+                while let Some((buffer, ranges)) = search.next().await {
+                    results.entry(buffer).or_insert(ranges);
                 }
+                results
+            });
+            search.await;
         }
 
         ClientOperation::WriteFsEntry {
@@ -1591,10 +1593,11 @@ impl TestPlan {
                     81.. => match self.rng.gen_range(0..100_u32) {
                         // Add a worktree to a local project
                         0..=50 => {
-                            let Some(project) = client
-                                .local_projects()
-                                .choose(&mut self.rng)
-                                .cloned() else { continue };
+                            let Some(project) =
+                                client.local_projects().choose(&mut self.rng).cloned()
+                            else {
+                                continue;
+                            };
                             let project_root_name = root_name_for_project(&project, cx);
                             let mut paths = client.fs().paths(false);
                             paths.remove(0);
@@ -1611,7 +1614,9 @@ impl TestPlan {
 
                         // Add an entry to a worktree
                         _ => {
-                            let Some(project) = choose_random_project(client, &mut self.rng) else { continue };
+                            let Some(project) = choose_random_project(client, &mut self.rng) else {
+                                continue;
+                            };
                             let project_root_name = root_name_for_project(&project, cx);
                             let is_local = project.read_with(cx, |project, _| project.is_local());
                             let worktree = project.read_with(cx, |project, cx| {
@@ -1645,7 +1650,9 @@ impl TestPlan {
 
                 // Query and mutate buffers
                 60..=90 => {
-                    let Some(project) = choose_random_project(client, &mut self.rng) else { continue };
+                    let Some(project) = choose_random_project(client, &mut self.rng) else {
+                        continue;
+                    };
                     let project_root_name = root_name_for_project(&project, cx);
                     let is_local = project.read_with(cx, |project, _| project.is_local());
 
@@ -1656,7 +1663,10 @@ impl TestPlan {
                                 .buffers_for_project(&project)
                                 .iter()
                                 .choose(&mut self.rng)
-                                .cloned() else { continue };
+                                .cloned()
+                            else {
+                                continue;
+                            };
 
                             let full_path = buffer
                                 .read_with(cx, |buffer, cx| buffer.file().unwrap().full_path(cx));
@@ -2026,7 +2036,10 @@ async fn simulate_client(
     client.app_state.languages.add(Arc::new(language));
 
     while let Some(batch_id) = operation_rx.next().await {
-        let Some((operation, applied)) = plan.lock().next_client_operation(&client, batch_id, &cx) else { break };
+        let Some((operation, applied)) = plan.lock().next_client_operation(&client, batch_id, &cx)
+        else {
+            break;
+        };
         applied.store(true, SeqCst);
         match apply_client_operation(&client, operation, &mut cx).await {
             Ok(()) => {}

crates/collab_ui/Cargo.toml

@@ -26,6 +26,7 @@ auto_update = { path = "../auto_update" }
 db = { path = "../db" }
 call = { path = "../call" }
 client = { path = "../client" }
+channel = { path = "../channel" }
 clock = { path = "../clock" }
 collections = { path = "../collections" }
 context_menu = { path = "../context_menu" }
@@ -33,12 +34,13 @@ editor = { path = "../editor" }
 feedback = { path = "../feedback" }
 fuzzy = { path = "../fuzzy" }
 gpui = { path = "../gpui" }
+language = { path = "../language" }
 menu = { path = "../menu" }
 picker = { path = "../picker" }
 project = { path = "../project" }
 recent_projects = {path = "../recent_projects"}
 settings = { path = "../settings" }
-staff_mode = {path = "../staff_mode"}
+feature_flags = {path = "../feature_flags"}
 theme = { path = "../theme" }
 theme_selector = { path = "../theme_selector" }
 vcs_menu = { path = "../vcs_menu" }

crates/collab_ui/src/channel_view.rs

@@ -0,0 +1,355 @@
+use anyhow::{anyhow, Result};
+use channel::{
+    channel_buffer::{self, ChannelBuffer},
+    ChannelId,
+};
+use client::proto;
+use clock::ReplicaId;
+use collections::HashMap;
+use editor::Editor;
+use gpui::{
+    actions,
+    elements::{ChildView, Label},
+    geometry::vector::Vector2F,
+    AnyElement, AnyViewHandle, AppContext, Element, Entity, ModelHandle, Subscription, Task, View,
+    ViewContext, ViewHandle,
+};
+use project::Project;
+use std::any::Any;
+use workspace::{
+    item::{FollowableItem, Item, ItemHandle},
+    register_followable_item,
+    searchable::SearchableItemHandle,
+    ItemNavHistory, Pane, ViewId, Workspace, WorkspaceId,
+};
+
+actions!(channel_view, [Deploy]);
+
+pub(crate) fn init(cx: &mut AppContext) {
+    register_followable_item::<ChannelView>(cx)
+}
+
+pub struct ChannelView {
+    pub editor: ViewHandle<Editor>,
+    project: ModelHandle<Project>,
+    channel_buffer: ModelHandle<ChannelBuffer>,
+    remote_id: Option<ViewId>,
+    _editor_event_subscription: Subscription,
+}
+
+impl ChannelView {
+    pub fn open(
+        channel_id: ChannelId,
+        pane: ViewHandle<Pane>,
+        workspace: ViewHandle<Workspace>,
+        cx: &mut AppContext,
+    ) -> Task<Result<ViewHandle<Self>>> {
+        let workspace = workspace.read(cx);
+        let project = workspace.project().to_owned();
+        let channel_store = workspace.app_state().channel_store.clone();
+        let markdown = workspace
+            .app_state()
+            .languages
+            .language_for_name("Markdown");
+        let channel_buffer =
+            channel_store.update(cx, |store, cx| store.open_channel_buffer(channel_id, cx));
+
+        cx.spawn(|mut cx| async move {
+            let channel_buffer = channel_buffer.await?;
+            let markdown = markdown.await?;
+            channel_buffer.update(&mut cx, |buffer, cx| {
+                buffer.buffer().update(cx, |buffer, cx| {
+                    buffer.set_language(Some(markdown), cx);
+                })
+            });
+
+            pane.update(&mut cx, |pane, cx| {
+                pane.items_of_type::<Self>()
+                    .find(|channel_view| channel_view.read(cx).channel_buffer == channel_buffer)
+                    .unwrap_or_else(|| cx.add_view(|cx| Self::new(project, channel_buffer, cx)))
+            })
+            .ok_or_else(|| anyhow!("pane was dropped"))
+        })
+    }
+
+    pub fn new(
+        project: ModelHandle<Project>,
+        channel_buffer: ModelHandle<ChannelBuffer>,
+        cx: &mut ViewContext<Self>,
+    ) -> Self {
+        let buffer = channel_buffer.read(cx).buffer();
+        // buffer.update(cx, |buffer, cx| buffer.set_language(language, cx));
+        let editor = cx.add_view(|cx| Editor::for_buffer(buffer, None, cx));
+        let _editor_event_subscription = cx.subscribe(&editor, |_, _, e, cx| cx.emit(e.clone()));
+
+        cx.subscribe(&project, Self::handle_project_event).detach();
+        cx.subscribe(&channel_buffer, Self::handle_channel_buffer_event)
+            .detach();
+
+        let this = Self {
+            editor,
+            project,
+            channel_buffer,
+            remote_id: None,
+            _editor_event_subscription,
+        };
+        this.refresh_replica_id_map(cx);
+        this
+    }
+
+    fn handle_project_event(
+        &mut self,
+        _: ModelHandle<Project>,
+        event: &project::Event,
+        cx: &mut ViewContext<Self>,
+    ) {
+        match event {
+            project::Event::RemoteIdChanged(_) => {}
+            project::Event::DisconnectedFromHost => {}
+            project::Event::Closed => {}
+            project::Event::CollaboratorUpdated { .. } => {}
+            project::Event::CollaboratorLeft(_) => {}
+            project::Event::CollaboratorJoined(_) => {}
+            _ => return,
+        }
+        self.refresh_replica_id_map(cx);
+    }
+
+    fn handle_channel_buffer_event(
+        &mut self,
+        _: ModelHandle<ChannelBuffer>,
+        event: &channel_buffer::Event,
+        cx: &mut ViewContext<Self>,
+    ) {
+        match event {
+            channel_buffer::Event::CollaboratorsChanged => {
+                self.refresh_replica_id_map(cx);
+            }
+            channel_buffer::Event::Disconnected => self.editor.update(cx, |editor, cx| {
+                editor.set_read_only(true);
+                cx.notify();
+            }),
+        }
+    }
+
+    /// Build a mapping of channel buffer replica ids to the corresponding
+    /// replica ids in the current project.
+    ///
+    /// Using this mapping, a given user can be displayed with the same color
+    /// in the channel buffer as in other files in the project. Users who are
+    /// in the channel buffer but not the project will not have a color.
+    fn refresh_replica_id_map(&self, cx: &mut ViewContext<Self>) {
+        let mut project_replica_ids_by_channel_buffer_replica_id = HashMap::default();
+        let project = self.project.read(cx);
+        let channel_buffer = self.channel_buffer.read(cx);
+        project_replica_ids_by_channel_buffer_replica_id
+            .insert(channel_buffer.replica_id(cx), project.replica_id());
+        project_replica_ids_by_channel_buffer_replica_id.extend(
+            channel_buffer
+                .collaborators()
+                .iter()
+                .filter_map(|channel_buffer_collaborator| {
+                    project
+                        .collaborators()
+                        .values()
+                        .find_map(|project_collaborator| {
+                            (project_collaborator.user_id == channel_buffer_collaborator.user_id)
+                                .then_some((
+                                    channel_buffer_collaborator.replica_id as ReplicaId,
+                                    project_collaborator.replica_id,
+                                ))
+                        })
+                }),
+        );
+
+        self.editor.update(cx, |editor, cx| {
+            editor.set_replica_id_map(Some(project_replica_ids_by_channel_buffer_replica_id), cx)
+        });
+    }
+}
+
+impl Entity for ChannelView {
+    type Event = editor::Event;
+}
+
+impl View for ChannelView {
+    fn ui_name() -> &'static str {
+        "ChannelView"
+    }
+
+    fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
+        ChildView::new(self.editor.as_any(), cx).into_any()
+    }
+
+    fn focus_in(&mut self, _: AnyViewHandle, cx: &mut ViewContext<Self>) {
+        if cx.is_self_focused() {
+            cx.focus(self.editor.as_any())
+        }
+    }
+}
+
+impl Item for ChannelView {
+    fn tab_content<V: 'static>(
+        &self,
+        _: Option<usize>,
+        style: &theme::Tab,
+        cx: &gpui::AppContext,
+    ) -> AnyElement<V> {
+        let channel_name = &self.channel_buffer.read(cx).channel().name;
+        let label = if self.channel_buffer.read(cx).is_connected() {
+            format!("#{}", channel_name)
+        } else {
+            format!("#{} (disconnected)", channel_name)
+        };
+        Label::new(label, style.label.to_owned()).into_any()
+    }
+
+    fn clone_on_split(&self, _: WorkspaceId, cx: &mut ViewContext<Self>) -> Option<Self> {
+        Some(Self::new(
+            self.project.clone(),
+            self.channel_buffer.clone(),
+            cx,
+        ))
+    }
+
+    fn is_singleton(&self, _cx: &AppContext) -> bool {
+        true
+    }
+
+    fn navigate(&mut self, data: Box<dyn Any>, cx: &mut ViewContext<Self>) -> bool {
+        self.editor
+            .update(cx, |editor, cx| editor.navigate(data, cx))
+    }
+
+    fn deactivated(&mut self, cx: &mut ViewContext<Self>) {
+        self.editor
+            .update(cx, |editor, cx| Item::deactivated(editor, cx))
+    }
+
+    fn set_nav_history(&mut self, history: ItemNavHistory, cx: &mut ViewContext<Self>) {
+        self.editor
+            .update(cx, |editor, cx| Item::set_nav_history(editor, history, cx))
+    }
+
+    fn as_searchable(&self, _: &ViewHandle<Self>) -> Option<Box<dyn SearchableItemHandle>> {
+        Some(Box::new(self.editor.clone()))
+    }
+
+    fn show_toolbar(&self) -> bool {
+        true
+    }
+
+    fn pixel_position_of_cursor(&self, cx: &AppContext) -> Option<Vector2F> {
+        self.editor.read(cx).pixel_position_of_cursor(cx)
+    }
+}
+
+impl FollowableItem for ChannelView {
+    fn remote_id(&self) -> Option<workspace::ViewId> {
+        self.remote_id
+    }
+
+    fn to_state_proto(&self, cx: &AppContext) -> Option<proto::view::Variant> {
+        let channel = self.channel_buffer.read(cx).channel();
+        Some(proto::view::Variant::ChannelView(
+            proto::view::ChannelView {
+                channel_id: channel.id,
+                editor: if let Some(proto::view::Variant::Editor(proto)) =
+                    self.editor.read(cx).to_state_proto(cx)
+                {
+                    Some(proto)
+                } else {
+                    None
+                },
+            },
+        ))
+    }
+
+    fn from_state_proto(
+        pane: ViewHandle<workspace::Pane>,
+        workspace: ViewHandle<workspace::Workspace>,
+        remote_id: workspace::ViewId,
+        state: &mut Option<proto::view::Variant>,
+        cx: &mut AppContext,
+    ) -> Option<gpui::Task<anyhow::Result<ViewHandle<Self>>>> {
+        let Some(proto::view::Variant::ChannelView(_)) = state else {
+            return None;
+        };
+        let Some(proto::view::Variant::ChannelView(state)) = state.take() else {
+            unreachable!()
+        };
+
+        let open = ChannelView::open(state.channel_id, pane, workspace, cx);
+
+        Some(cx.spawn(|mut cx| async move {
+            let this = open.await?;
+
+            let task = this
+                .update(&mut cx, |this, cx| {
+                    this.remote_id = Some(remote_id);
+
+                    if let Some(state) = state.editor {
+                        Some(this.editor.update(cx, |editor, cx| {
+                            editor.apply_update_proto(
+                                &this.project,
+                                proto::update_view::Variant::Editor(proto::update_view::Editor {
+                                    selections: state.selections,
+                                    pending_selection: state.pending_selection,
+                                    scroll_top_anchor: state.scroll_top_anchor,
+                                    scroll_x: state.scroll_x,
+                                    scroll_y: state.scroll_y,
+                                    ..Default::default()
+                                }),
+                                cx,
+                            )
+                        }))
+                    } else {
+                        None
+                    }
+                })
+                .ok_or_else(|| anyhow!("window was closed"))?;
+
+            if let Some(task) = task {
+                task.await?;
+            }
+
+            Ok(this)
+        }))
+    }
+
+    fn add_event_to_update_proto(
+        &self,
+        event: &Self::Event,
+        update: &mut Option<proto::update_view::Variant>,
+        cx: &AppContext,
+    ) -> bool {
+        self.editor
+            .read(cx)
+            .add_event_to_update_proto(event, update, cx)
+    }
+
+    fn apply_update_proto(
+        &mut self,
+        project: &ModelHandle<Project>,
+        message: proto::update_view::Variant,
+        cx: &mut ViewContext<Self>,
+    ) -> gpui::Task<anyhow::Result<()>> {
+        self.editor.update(cx, |editor, cx| {
+            editor.apply_update_proto(project, message, cx)
+        })
+    }
+
+    fn set_leader_replica_id(
+        &mut self,
+        leader_replica_id: Option<u16>,
+        cx: &mut ViewContext<Self>,
+    ) {
+        self.editor.update(cx, |editor, cx| {
+            editor.set_leader_replica_id(leader_replica_id, cx)
+        })
+    }
+
+    fn should_unfollow_on_event(event: &Self::Event, cx: &AppContext) -> bool {
+        Editor::should_unfollow_on_event(event, cx)
+    }
+}

crates/collab_ui/src/collab_panel.rs

@@ -4,28 +4,30 @@ mod panel_settings;
 
 use anyhow::Result;
 use call::ActiveCall;
-use client::{
-    proto::PeerId, Channel, ChannelEvent, ChannelId, ChannelStore, Client, Contact, User, UserStore,
-};
-
+use channel::{Channel, ChannelEvent, ChannelId, ChannelStore};
+use client::{proto::PeerId, Client, Contact, User, UserStore};
 use context_menu::{ContextMenu, ContextMenuItem};
 use db::kvp::KEY_VALUE_STORE;
 use editor::{Cancel, Editor};
+
+use feature_flags::{ChannelsAlpha, FeatureFlagAppExt, FeatureFlagViewExt};
 use futures::StreamExt;
 use fuzzy::{match_strings, StringMatchCandidate};
 use gpui::{
     actions,
     elements::{
-        Canvas, ChildView, Empty, Flex, Image, Label, List, ListOffset, ListState,
-        MouseEventHandler, Orientation, OverlayPositionMode, Padding, ParentElement, Stack, Svg,
+        Canvas, ChildView, Component, Empty, Flex, Image, Label, List, ListOffset, ListState,
+        MouseEventHandler, Orientation, OverlayPositionMode, Padding, ParentElement, SafeStylable,
+        Stack, Svg,
     },
+    fonts::TextStyle,
     geometry::{
         rect::RectF,
         vector::{vec2f, Vector2F},
     },
     impl_actions,
     platform::{CursorStyle, MouseButton, PromptLevel},
-    serde_json, AnyElement, AppContext, AsyncAppContext, Element, Entity, ModelHandle,
+    serde_json, AnyElement, AppContext, AsyncAppContext, Element, Entity, FontCache, ModelHandle,
     Subscription, Task, View, ViewContext, ViewHandle, WeakViewHandle,
 };
 use menu::{Confirm, SelectNext, SelectPrev};
@@ -33,9 +35,8 @@ use panel_settings::{CollaborationPanelDockPosition, CollaborationPanelSettings}
 use project::{Fs, Project};
 use serde_derive::{Deserialize, Serialize};
 use settings::SettingsStore;
-use staff_mode::StaffMode;
 use std::{borrow::Cow, mem, sync::Arc};
-use theme::IconButton;
+use theme::{components::ComponentExt, IconButton};
 use util::{iife, ResultExt, TryFutureExt};
 use workspace::{
     dock::{DockPosition, Panel},
@@ -43,7 +44,10 @@ use workspace::{
     Workspace,
 };
 
-use crate::face_pile::FacePile;
+use crate::{
+    channel_view::{self, ChannelView},
+    face_pile::FacePile,
+};
 use channel_modal::ChannelModal;
 
 use self::contact_finder::ContactFinder;
@@ -53,6 +57,11 @@ struct RemoveChannel {
     channel_id: u64,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+struct ToggleCollapse {
+    channel_id: u64,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
 struct NewChannel {
     channel_id: u64,
@@ -73,7 +82,21 @@ struct RenameChannel {
     channel_id: u64,
 }
 
-actions!(collab_panel, [ToggleFocus, Remove, Secondary]);
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+struct OpenChannelBuffer {
+    channel_id: u64,
+}
+
+actions!(
+    collab_panel,
+    [
+        ToggleFocus,
+        Remove,
+        Secondary,
+        CollapseSelectedChannel,
+        ExpandSelectedChannel
+    ]
+);
 
 impl_actions!(
     collab_panel,
@@ -82,7 +105,9 @@ impl_actions!(
         NewChannel,
         InviteMembers,
         ManageMembers,
-        RenameChannel
+        RenameChannel,
+        ToggleCollapse,
+        OpenChannelBuffer
     ]
 );
 
@@ -92,6 +117,7 @@ pub fn init(_client: Arc<Client>, cx: &mut AppContext) {
     settings::register::<panel_settings::CollaborationPanelSettings>(cx);
     contact_finder::init(cx);
     channel_modal::init(cx);
+    channel_view::init(cx);
 
     cx.add_action(CollabPanel::cancel);
     cx.add_action(CollabPanel::select_next);
@@ -105,6 +131,10 @@ pub fn init(_client: Arc<Client>, cx: &mut AppContext) {
     cx.add_action(CollabPanel::manage_members);
     cx.add_action(CollabPanel::rename_selected_channel);
     cx.add_action(CollabPanel::rename_channel);
+    cx.add_action(CollabPanel::toggle_channel_collapsed);
+    cx.add_action(CollabPanel::collapse_selected_channel);
+    cx.add_action(CollabPanel::expand_selected_channel);
+    cx.add_action(CollabPanel::open_channel_buffer);
 }
 
 #[derive(Debug)]
@@ -147,13 +177,15 @@ pub struct CollabPanel {
     list_state: ListState<Self>,
     subscriptions: Vec<Subscription>,
     collapsed_sections: Vec<Section>,
+    collapsed_channels: Vec<ChannelId>,
     workspace: WeakViewHandle<Workspace>,
     context_menu_on_selected: bool,
 }
 
 #[derive(Serialize, Deserialize)]
-struct SerializedChannelsPanel {
+struct SerializedCollabPanel {
     width: Option<f32>,
+    collapsed_channels: Option<Vec<ChannelId>>,
 }
 
 #[derive(Debug)]
@@ -198,6 +230,9 @@ enum ListEntry {
         channel: Arc<Channel>,
         depth: usize,
     },
+    ChannelNotes {
+        channel_id: ChannelId,
+    },
     ChannelEditor {
         depth: usize,
     },
@@ -341,6 +376,12 @@ impl CollabPanel {
                                 return channel_row;
                             }
                         }
+                        ListEntry::ChannelNotes { channel_id } => this.render_channel_notes(
+                            *channel_id,
+                            &theme.collab_panel,
+                            is_selected,
+                            cx,
+                        ),
                         ListEntry::ChannelInvite(channel) => Self::render_channel_invite(
                             channel.clone(),
                             this.channel_store.clone(),
@@ -398,6 +439,7 @@ impl CollabPanel {
                 subscriptions: Vec::default(),
                 match_candidates: Vec::default(),
                 collapsed_sections: vec![Section::Offline],
+                collapsed_channels: Vec::default(),
                 workspace: workspace.weak_handle(),
                 client: workspace.app_state().client.clone(),
                 context_menu_on_selected: true,
@@ -431,9 +473,10 @@ impl CollabPanel {
                 }));
             this.subscriptions
                 .push(cx.observe(&active_call, |this, _, cx| this.update_entries(true, cx)));
-            this.subscriptions.push(
-                cx.observe_global::<StaffMode, _>(move |this, cx| this.update_entries(true, cx)),
-            );
+            this.subscriptions
+                .push(cx.observe_flag::<ChannelsAlpha, _>(move |_, this, cx| {
+                    this.update_entries(true, cx)
+                }));
             this.subscriptions.push(cx.subscribe(
                 &this.channel_store,
                 |this, _channel_store, e, cx| match e {
@@ -469,7 +512,7 @@ impl CollabPanel {
                 .log_err()
                 .flatten()
             {
-                Some(serde_json::from_str::<SerializedChannelsPanel>(&panel)?)
+                Some(serde_json::from_str::<SerializedCollabPanel>(&panel)?)
             } else {
                 None
             };
@@ -479,6 +522,9 @@ impl CollabPanel {
                 if let Some(serialized_panel) = serialized_panel {
                     panel.update(cx, |panel, cx| {
                         panel.width = serialized_panel.width;
+                        panel.collapsed_channels = serialized_panel
+                            .collapsed_channels
+                            .unwrap_or_else(|| Vec::new());
                         cx.notify();
                     });
                 }
@@ -489,12 +535,16 @@ impl CollabPanel {
 
     fn serialize(&mut self, cx: &mut ViewContext<Self>) {
         let width = self.width;
+        let collapsed_channels = self.collapsed_channels.clone();
         self.pending_serialization = cx.background().spawn(
             async move {
                 KEY_VALUE_STORE
                     .write_kvp(
                         COLLABORATION_PANEL_KEY.into(),
-                        serde_json::to_string(&SerializedChannelsPanel { width })?,
+                        serde_json::to_string(&SerializedCollabPanel {
+                            width,
+                            collapsed_channels: Some(collapsed_channels),
+                        })?,
                     )
                     .await?;
                 anyhow::Ok(())
@@ -518,6 +568,10 @@ impl CollabPanel {
             if !self.collapsed_sections.contains(&Section::ActiveCall) {
                 let room = room.read(cx);
 
+                if let Some(channel_id) = room.channel_id() {
+                    self.entries.push(ListEntry::ChannelNotes { channel_id })
+                }
+
                 // Populate the active user.
                 if let Some(user) = user_store.current_user() {
                     self.match_candidates.clear();
@@ -622,7 +676,8 @@ impl CollabPanel {
         }
 
         let mut request_entries = Vec::new();
-        if self.include_channels_section(cx) {
+
+        if cx.has_flag::<ChannelsAlpha>() {
             self.entries.push(ListEntry::Header(Section::Channels, 0));
 
             if channel_store.channel_count() > 0 || self.channel_editing_state.is_some() {
@@ -657,10 +712,24 @@ impl CollabPanel {
                         self.entries.push(ListEntry::ChannelEditor { depth: 0 });
                     }
                 }
+                let mut collapse_depth = None;
                 for mat in matches {
                     let (depth, channel) =
                         channel_store.channel_at_index(mat.candidate_id).unwrap();
 
+                    if collapse_depth.is_none() && self.is_channel_collapsed(channel.id) {
+                        collapse_depth = Some(depth);
+                    } else if let Some(collapsed_depth) = collapse_depth {
+                        if depth > collapsed_depth {
+                            continue;
+                        }
+                        if self.is_channel_collapsed(channel.id) {
+                            collapse_depth = Some(depth);
+                        } else {
+                            collapse_depth = None;
+                        }
+                    }
+
                     match &self.channel_editing_state {
                         Some(ChannelEditingState::Create { parent_id, .. })
                             if *parent_id == Some(channel.id) =>
@@ -963,25 +1032,19 @@ impl CollabPanel {
     ) -> AnyElement<Self> {
         enum JoinProject {}
 
-        let font_cache = cx.font_cache();
-        let host_avatar_height = theme
+        let host_avatar_width = theme
             .contact_avatar
             .width
             .or(theme.contact_avatar.height)
             .unwrap_or(0.);
-        let row = &theme.project_row.inactive_state().default;
         let tree_branch = theme.tree_branch;
-        let line_height = row.name.text.line_height(font_cache);
-        let cap_height = row.name.text.cap_height(font_cache);
-        let baseline_offset =
-            row.name.text.baseline_offset(font_cache) + (theme.row_height - line_height) / 2.;
         let project_name = if worktree_root_names.is_empty() {
             "untitled".to_string()
         } else {
             worktree_root_names.join(", ")
         };
 
-        MouseEventHandler::new::<JoinProject, _>(project_id as usize, cx, |mouse_state, _| {
+        MouseEventHandler::new::<JoinProject, _>(project_id as usize, cx, |mouse_state, cx| {
             let tree_branch = *tree_branch.in_state(is_selected).style_for(mouse_state);
             let row = theme
                 .project_row
@@ -989,39 +1052,20 @@ impl CollabPanel {
                 .style_for(mouse_state);
 
             Flex::row()
+                .with_child(render_tree_branch(
+                    tree_branch,
+                    &row.name.text,
+                    is_last,
+                    vec2f(host_avatar_width, theme.row_height),
+                    cx.font_cache(),
+                ))
                 .with_child(
-                    Stack::new()
-                        .with_child(Canvas::new(move |scene, bounds, _, _, _| {
-                            let start_x =
-                                bounds.min_x() + (bounds.width() / 2.) - (tree_branch.width / 2.);
-                            let end_x = bounds.max_x();
-                            let start_y = bounds.min_y();
-                            let end_y = bounds.min_y() + baseline_offset - (cap_height / 2.);
-
-                            scene.push_quad(gpui::Quad {
-                                bounds: RectF::from_points(
-                                    vec2f(start_x, start_y),
-                                    vec2f(
-                                        start_x + tree_branch.width,
-                                        if is_last { end_y } else { bounds.max_y() },
-                                    ),
-                                ),
-                                background: Some(tree_branch.color),
-                                border: gpui::Border::default(),
-                                corner_radii: (0.).into(),
-                            });
-                            scene.push_quad(gpui::Quad {
-                                bounds: RectF::from_points(
-                                    vec2f(start_x, end_y),
-                                    vec2f(end_x, end_y + tree_branch.width),
-                                ),
-                                background: Some(tree_branch.color),
-                                border: gpui::Border::default(),
-                                corner_radii: (0.).into(),
-                            });
-                        }))
+                    Svg::new("icons/file_icons/folder.svg")
+                        .with_color(theme.channel_hash.color)
                         .constrained()
-                        .with_width(host_avatar_height),
+                        .with_width(theme.channel_hash.width)
+                        .aligned()
+                        .left(),
                 )
                 .with_child(
                     Label::new(project_name, row.name.text.clone())
@@ -1196,7 +1240,7 @@ impl CollabPanel {
                 });
 
                 if let Some(name) = channel_name {
-                    Cow::Owned(format!("Current Call - #{}", name))
+                    Cow::Owned(format!("#{}", name))
                 } else {
                     Cow::Borrowed("Current Call")
                 }
@@ -1332,7 +1376,7 @@ impl CollabPanel {
                 .with_cursor_style(CursorStyle::PointingHand)
                 .on_click(MouseButton::Left, move |_, this, cx| {
                     if can_collapse {
-                        this.toggle_expanded(section, cx);
+                        this.toggle_section_expanded(section, cx);
                     }
                 })
         }
@@ -1479,6 +1523,11 @@ impl CollabPanel {
         cx: &AppContext,
     ) -> AnyElement<Self> {
         Flex::row()
+            .with_child(
+                Empty::new()
+                    .constrained()
+                    .with_width(theme.collab_panel.disclosure.button_space()),
+            )
             .with_child(
                 Svg::new("icons/hash.svg")
                     .with_color(theme.collab_panel.channel_hash.color)
@@ -1537,6 +1586,10 @@ impl CollabPanel {
         cx: &mut ViewContext<Self>,
     ) -> AnyElement<Self> {
         let channel_id = channel.id;
+        let has_children = self.channel_store.read(cx).has_children(channel_id);
+        let disclosed =
+            has_children.then(|| !self.collapsed_channels.binary_search(&channel_id).is_ok());
+
         let is_active = iife!({
             let call_channel = ActiveCall::global(cx)
                 .read(cx)
@@ -1550,7 +1603,7 @@ impl CollabPanel {
         const FACEPILE_LIMIT: usize = 3;
 
         MouseEventHandler::new::<Channel, _>(channel.id as usize, cx, |state, cx| {
-            Flex::row()
+            Flex::<Self>::row()
                 .with_child(
                     Svg::new("icons/hash.svg")
                         .with_color(theme.channel_hash.color)
@@ -1599,6 +1652,11 @@ impl CollabPanel {
                     }
                 })
                 .align_children_center()
+                .styleable_component()
+                .disclosable(disclosed, Box::new(ToggleCollapse { channel_id }))
+                .with_id(channel_id as usize)
+                .with_style(theme.disclosure.clone())
+                .element()
                 .constrained()
                 .with_height(theme.row_height)
                 .contained()
@@ -1618,6 +1676,61 @@ impl CollabPanel {
         .into_any()
     }
 
+    fn render_channel_notes(
+        &self,
+        channel_id: ChannelId,
+        theme: &theme::CollabPanel,
+        is_selected: bool,
+        cx: &mut ViewContext<Self>,
+    ) -> AnyElement<Self> {
+        enum ChannelNotes {}
+        let host_avatar_width = theme
+            .contact_avatar
+            .width
+            .or(theme.contact_avatar.height)
+            .unwrap_or(0.);
+
+        MouseEventHandler::new::<ChannelNotes, _>(channel_id as usize, cx, |state, cx| {
+            let tree_branch = *theme.tree_branch.in_state(is_selected).style_for(state);
+            let row = theme.project_row.in_state(is_selected).style_for(state);
+
+            Flex::<Self>::row()
+                .with_child(render_tree_branch(
+                    tree_branch,
+                    &row.name.text,
+                    true,
+                    vec2f(host_avatar_width, theme.row_height),
+                    cx.font_cache(),
+                ))
+                .with_child(
+                    Svg::new("icons/radix/file.svg")
+                        .with_color(theme.channel_hash.color)
+                        .constrained()
+                        .with_width(theme.channel_hash.width)
+                        .aligned()
+                        .left(),
+                )
+                .with_child(
+                    Label::new("notes", theme.channel_name.text.clone())
+                        .contained()
+                        .with_style(theme.channel_name.container)
+                        .aligned()
+                        .left()
+                        .flex(1., true),
+                )
+                .constrained()
+                .with_height(theme.row_height)
+                .contained()
+                .with_style(*theme.channel_row.style_for(is_selected, state))
+                .with_padding_left(theme.channel_row.default_style().padding.left)
+        })
+        .on_click(MouseButton::Left, move |_, this, cx| {
+            this.open_channel_buffer(&OpenChannelBuffer { channel_id }, cx);
+        })
+        .with_cursor_style(CursorStyle::PointingHand)
+        .into_any()
+    }
+
     fn render_channel_invite(
         channel: Arc<Channel>,
         channel_store: ModelHandle<ChannelStore>,
@@ -1801,21 +1914,12 @@ impl CollabPanel {
             .into_any()
     }
 
-    fn include_channels_section(&self, cx: &AppContext) -> bool {
-        if cx.has_global::<StaffMode>() {
-            cx.global::<StaffMode>().0
-        } else {
-            false
-        }
-    }
-
     fn deploy_channel_context_menu(
         &mut self,
         position: Option<Vector2F>,
         channel_id: u64,
         cx: &mut ViewContext<Self>,
     ) {
-        if self.channel_store.read(cx).is_user_admin(channel_id) {
         self.context_menu_on_selected = position.is_none();
 
         self.context_menu.update(cx, |context_menu, cx| {
@@ -1825,6 +1929,30 @@ impl CollabPanel {
                 OverlayPositionMode::Window
             });
 
+            let expand_action_name = if self.is_channel_collapsed(channel_id) {
+                "Expand Subchannels"
+            } else {
+                "Collapse Subchannels"
+            };
+
+            let mut items = vec![
+                ContextMenuItem::action(expand_action_name, ToggleCollapse { channel_id }),
+                ContextMenuItem::action("Open Notes", OpenChannelBuffer { channel_id }),
+            ];
+
+            if self.channel_store.read(cx).is_user_admin(channel_id) {
+                items.extend([
+                    ContextMenuItem::Separator,
+                    ContextMenuItem::action("New Subchannel", NewChannel { channel_id }),
+                    ContextMenuItem::action("Rename", RenameChannel { channel_id }),
+                    ContextMenuItem::Separator,
+                    ContextMenuItem::action("Invite Members", InviteMembers { channel_id }),
+                    ContextMenuItem::action("Manage Members", ManageMembers { channel_id }),
+                    ContextMenuItem::Separator,
+                    ContextMenuItem::action("Delete", RemoveChannel { channel_id }),
+                ]);
+            }
+
             context_menu.show(
                 position.unwrap_or_default(),
                 if self.context_menu_on_selected {
@@ -1832,23 +1960,13 @@ impl CollabPanel {
                 } else {
                     gpui::elements::AnchorCorner::BottomLeft
                 },
-                    vec![
-                        ContextMenuItem::action("New Subchannel", NewChannel { channel_id }),
-                        ContextMenuItem::Separator,
-                        ContextMenuItem::action("Invite to Channel", InviteMembers { channel_id }),
-                        ContextMenuItem::Separator,
-                        ContextMenuItem::action("Rename", RenameChannel { channel_id }),
-                        ContextMenuItem::action("Manage", ManageMembers { channel_id }),
-                        ContextMenuItem::Separator,
-                        ContextMenuItem::action("Delete", RemoveChannel { channel_id }),
-                    ],
+                items,
                 cx,
             );
         });
 
         cx.notify();
     }
-    }
 
     fn cancel(&mut self, _: &Cancel, cx: &mut ViewContext<Self>) {
         if self.take_editing_state(cx) {
@@ -1912,7 +2030,7 @@ impl CollabPanel {
                         | Section::Online
                         | Section::Offline
                         | Section::ChannelInvites => {
-                            self.toggle_expanded(*section, cx);
+                            self.toggle_section_expanded(*section, cx);
                         }
                     },
                     ListEntry::Contact { contact, calling } => {
@@ -2000,7 +2118,7 @@ impl CollabPanel {
         }
     }
 
-    fn toggle_expanded(&mut self, section: Section, cx: &mut ViewContext<Self>) {
+    fn toggle_section_expanded(&mut self, section: Section, cx: &mut ViewContext<Self>) {
         if let Some(ix) = self.collapsed_sections.iter().position(|s| *s == section) {
             self.collapsed_sections.remove(ix);
         } else {
@@ -2009,6 +2127,55 @@ impl CollabPanel {
         self.update_entries(false, cx);
     }
 
+    fn collapse_selected_channel(
+        &mut self,
+        _: &CollapseSelectedChannel,
+        cx: &mut ViewContext<Self>,
+    ) {
+        let Some(channel_id) = self.selected_channel().map(|channel| channel.id) else {
+            return;
+        };
+
+        if self.is_channel_collapsed(channel_id) {
+            return;
+        }
+
+        self.toggle_channel_collapsed(&ToggleCollapse { channel_id }, cx)
+    }
+
+    fn expand_selected_channel(&mut self, _: &ExpandSelectedChannel, cx: &mut ViewContext<Self>) {
+        let Some(channel_id) = self.selected_channel().map(|channel| channel.id) else {
+            return;
+        };
+
+        if !self.is_channel_collapsed(channel_id) {
+            return;
+        }
+
+        self.toggle_channel_collapsed(&ToggleCollapse { channel_id }, cx)
+    }
+
+    fn toggle_channel_collapsed(&mut self, action: &ToggleCollapse, cx: &mut ViewContext<Self>) {
+        let channel_id = action.channel_id;
+
+        match self.collapsed_channels.binary_search(&channel_id) {
+            Ok(ix) => {
+                self.collapsed_channels.remove(ix);
+            }
+            Err(ix) => {
+                self.collapsed_channels.insert(ix, channel_id);
+            }
+        };
+        self.serialize(cx);
+        self.update_entries(true, cx);
+        cx.notify();
+        cx.focus_self();
+    }
+
+    fn is_channel_collapsed(&self, channel: ChannelId) -> bool {
+        self.collapsed_channels.binary_search(&channel).is_ok()
+    }
+
     fn leave_call(cx: &mut ViewContext<Self>) {
         ActiveCall::global(cx)
             .update(cx, |call, cx| call.hang_up(cx))
@@ -2048,6 +2215,8 @@ impl CollabPanel {
     }
 
     fn new_subchannel(&mut self, action: &NewChannel, cx: &mut ViewContext<Self>) {
+        self.collapsed_channels
+            .retain(|&channel| channel != action.channel_id);
         self.channel_editing_state = Some(ChannelEditingState::Create {
             parent_id: Some(action.channel_id),
             pending_name: None,
@@ -2103,6 +2272,21 @@ impl CollabPanel {
         }
     }
 
+    fn open_channel_buffer(&mut self, action: &OpenChannelBuffer, cx: &mut ViewContext<Self>) {
+        if let Some(workspace) = self.workspace.upgrade(cx) {
+            let pane = workspace.read(cx).active_pane().clone();
+            let channel_view = ChannelView::open(action.channel_id, pane.clone(), workspace, cx);
+            cx.spawn(|_, mut cx| async move {
+                let channel_view = channel_view.await?;
+                pane.update(&mut cx, |pane, cx| {
+                    pane.add_item(Box::new(channel_view), true, true, None, cx)
+                });
+                anyhow::Ok(())
+            })
+            .detach();
+        }
+    }
+
     fn show_inline_context_menu(&mut self, _: &menu::ShowContextMenu, cx: &mut ViewContext<Self>) {
         let Some(channel) = self.selected_channel() else {
             return;
@@ -2261,6 +2445,51 @@ impl CollabPanel {
     }
 }
 
+fn render_tree_branch(
+    branch_style: theme::TreeBranch,
+    row_style: &TextStyle,
+    is_last: bool,
+    size: Vector2F,
+    font_cache: &FontCache,
+) -> gpui::elements::ConstrainedBox<CollabPanel> {
+    let line_height = row_style.line_height(font_cache);
+    let cap_height = row_style.cap_height(font_cache);
+    let baseline_offset = row_style.baseline_offset(font_cache) + (size.y() - line_height) / 2.;
+
+    Canvas::new(move |scene, bounds, _, _, _| {
+        scene.paint_layer(None, |scene| {
+            let start_x = bounds.min_x() + (bounds.width() / 2.) - (branch_style.width / 2.);
+            let end_x = bounds.max_x();
+            let start_y = bounds.min_y();
+            let end_y = bounds.min_y() + baseline_offset - (cap_height / 2.);
+
+            scene.push_quad(gpui::Quad {
+                bounds: RectF::from_points(
+                    vec2f(start_x, start_y),
+                    vec2f(
+                        start_x + branch_style.width,
+                        if is_last { end_y } else { bounds.max_y() },
+                    ),
+                ),
+                background: Some(branch_style.color),
+                border: gpui::Border::default(),
+                corner_radii: (0.).into(),
+            });
+            scene.push_quad(gpui::Quad {
+                bounds: RectF::from_points(
+                    vec2f(start_x, end_y),
+                    vec2f(end_x, end_y + branch_style.width),
+                ),
+                background: Some(branch_style.color),
+                border: gpui::Border::default(),
+                corner_radii: (0.).into(),
+            });
+        })
+    })
+    .constrained()
+    .with_width(size.x())
+}
+
 impl View for CollabPanel {
     fn ui_name() -> &'static str {
         "CollabPanel"
@@ -2470,6 +2699,14 @@ impl PartialEq for ListEntry {
                     return channel_1.id == channel_2.id && depth_1 == depth_2;
                 }
             }
+            ListEntry::ChannelNotes { channel_id } => {
+                if let ListEntry::ChannelNotes {
+                    channel_id: other_id,
+                } = other
+                {
+                    return channel_id == other_id;
+                }
+            }
             ListEntry::ChannelInvite(channel_1) => {
                 if let ListEntry::ChannelInvite(channel_2) = other {
                     return channel_1.id == channel_2.id;

crates/collab_ui/src/collab_panel/channel_modal.rs

@@ -1,4 +1,5 @@
-use client::{proto, ChannelId, ChannelMembership, ChannelStore, User, UserId, UserStore};
+use channel::{ChannelId, ChannelMembership, ChannelStore};
+use client::{proto, User, UserId, UserStore};
 use context_menu::{ContextMenu, ContextMenuItem};
 use fuzzy::{match_strings, StringMatchCandidate};
 use gpui::{
@@ -151,11 +152,8 @@ impl View for ChannelModal {
         let theme = &theme::current(cx).collab_panel.tabbed_modal;
 
         let mode = self.picker.read(cx).delegate().mode;
-        let Some(channel) = self
-            .channel_store
-            .read(cx)
-            .channel_for_id(self.channel_id) else {
-                return Empty::new().into_any()
+        let Some(channel) = self.channel_store.read(cx).channel_for_id(self.channel_id) else {
+            return Empty::new().into_any();
         };
 
         enum InviteMembers {}

crates/collab_ui/src/collab_ui.rs

@@ -1,3 +1,4 @@
+pub mod channel_view;
 pub mod collab_panel;
 mod collab_titlebar_item;
 mod contact_notification;

crates/component_test/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "component_test"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[lib]
+path = "src/component_test.rs"
+doctest = false
+
+[dependencies]
+anyhow.workspace = true
+gpui = { path = "../gpui" }
+settings = { path = "../settings" }
+util = { path = "../util" }
+theme = { path = "../theme" }
+workspace = { path = "../workspace" }
+project = { path = "../project" }

crates/component_test/src/component_test.rs

@@ -0,0 +1,121 @@
+use gpui::{
+    actions,
+    elements::{Component, Flex, ParentElement, SafeStylable},
+    AppContext, Element, Entity, ModelHandle, Task, View, ViewContext, ViewHandle, WeakViewHandle,
+};
+use project::Project;
+use theme::components::{action_button::Button, label::Label, ComponentExt};
+use workspace::{
+    item::Item, register_deserializable_item, ItemId, Pane, PaneBackdrop, Workspace, WorkspaceId,
+};
+
+pub fn init(cx: &mut AppContext) {
+    cx.add_action(ComponentTest::toggle_disclosure);
+    cx.add_action(ComponentTest::toggle_toggle);
+    cx.add_action(ComponentTest::deploy);
+    register_deserializable_item::<ComponentTest>(cx);
+}
+
+actions!(
+    test,
+    [NoAction, ToggleDisclosure, ToggleToggle, NewComponentTest]
+);
+
+struct ComponentTest {
+    disclosed: bool,
+    toggled: bool,
+}
+
+impl ComponentTest {
+    fn new() -> Self {
+        Self {
+            disclosed: false,
+            toggled: false,
+        }
+    }
+
+    fn deploy(workspace: &mut Workspace, _: &NewComponentTest, cx: &mut ViewContext<Workspace>) {
+        workspace.add_item(Box::new(cx.add_view(|_| ComponentTest::new())), cx);
+    }
+
+    fn toggle_disclosure(&mut self, _: &ToggleDisclosure, cx: &mut ViewContext<Self>) {
+        self.disclosed = !self.disclosed;
+        cx.notify();
+    }
+
+    fn toggle_toggle(&mut self, _: &ToggleToggle, cx: &mut ViewContext<Self>) {
+        self.toggled = !self.toggled;
+        cx.notify();
+    }
+}
+
+impl Entity for ComponentTest {
+    type Event = ();
+}
+
+impl View for ComponentTest {
+    fn ui_name() -> &'static str {
+        "Component Test"
+    }
+
+    fn render(&mut self, cx: &mut gpui::ViewContext<Self>) -> gpui::AnyElement<Self> {
+        let theme = theme::current(cx);
+
+        PaneBackdrop::new(
+            cx.view_id(),
+            Flex::column()
+                .with_spacing(10.)
+                .with_child(
+                    Button::action(NoAction)
+                        .with_tooltip("Here's what a tooltip looks like", theme.tooltip.clone())
+                        .with_contents(Label::new("Click me!"))
+                        .with_style(theme.component_test.button.clone())
+                        .element(),
+                )
+                .with_child(
+                    Button::action(ToggleToggle)
+                        .with_tooltip("Here's what a tooltip looks like", theme.tooltip.clone())
+                        .with_contents(Label::new("Toggle me!"))
+                        .toggleable(self.toggled)
+                        .with_style(theme.component_test.toggle.clone())
+                        .element(),
+                )
+                .with_child(
+                    Label::new("A disclosure")
+                        .disclosable(Some(self.disclosed), Box::new(ToggleDisclosure))
+                        .with_style(theme.component_test.disclosure.clone())
+                        .element(),
+                )
+                .constrained()
+                .with_width(200.)
+                .aligned()
+                .into_any(),
+        )
+        .into_any()
+    }
+}
+
+impl Item for ComponentTest {
+    fn tab_content<V: 'static>(
+        &self,
+        _: Option<usize>,
+        style: &theme::Tab,
+        _: &AppContext,
+    ) -> gpui::AnyElement<V> {
+        gpui::elements::Label::new("Component test", style.label.clone()).into_any()
+    }
+
+    fn serialized_item_kind() -> Option<&'static str> {
+        Some("ComponentTest")
+    }
+
+    fn deserialize(
+        _project: ModelHandle<Project>,
+        _workspace: WeakViewHandle<Workspace>,
+        _workspace_id: WorkspaceId,
+        _item_id: ItemId,
+        cx: &mut ViewContext<Pane>,
+    ) -> Task<anyhow::Result<ViewHandle<Self>>> {
+        Task::ready(Ok(cx.add_view(|_| Self::new())))
+    }
+}

crates/copilot/src/copilot.rs

@@ -980,7 +980,7 @@ mod tests {
         deterministic.forbid_parking();
         let (copilot, mut lsp) = Copilot::fake(cx);
 
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "Hello", cx));
+        let buffer_1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "Hello"));
         let buffer_1_uri: lsp::Url = format!("buffer://{}", buffer_1.id()).parse().unwrap();
         copilot.update(cx, |copilot, cx| copilot.register_buffer(&buffer_1, cx));
         assert_eq!(
@@ -996,7 +996,7 @@ mod tests {
             }
         );
 
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "Goodbye", cx));
+        let buffer_2 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "Goodbye"));
         let buffer_2_uri: lsp::Url = format!("buffer://{}", buffer_2.id()).parse().unwrap();
         copilot.update(cx, |copilot, cx| copilot.register_buffer(&buffer_2, cx));
         assert_eq!(

crates/editor/src/display_map.rs

@@ -4,7 +4,10 @@ mod inlay_map;
 mod tab_map;
 mod wrap_map;
 
-use crate::{Anchor, AnchorRangeExt, InlayId, MultiBuffer, MultiBufferSnapshot, ToOffset, ToPoint};
+use crate::{
+    link_go_to_definition::{DocumentRange, InlayRange},
+    Anchor, AnchorRangeExt, InlayId, MultiBuffer, MultiBufferSnapshot, ToOffset, ToPoint,
+};
 pub use block_map::{BlockMap, BlockPoint};
 use collections::{HashMap, HashSet};
 use fold_map::FoldMap;
@@ -27,7 +30,8 @@ pub use block_map::{
     BlockDisposition, BlockId, BlockProperties, BlockStyle, RenderBlock, TransformBlock,
 };
 
-pub use self::inlay_map::Inlay;
+pub use self::fold_map::FoldPoint;
+pub use self::inlay_map::{Inlay, InlayOffset, InlayPoint};
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum FoldStatus {
@@ -39,7 +43,7 @@ pub trait ToDisplayPoint {
     fn to_display_point(&self, map: &DisplaySnapshot) -> DisplayPoint;
 }
 
-type TextHighlights = TreeMap<Option<TypeId>, Arc<(HighlightStyle, Vec<Range<Anchor>>)>>;
+type TextHighlights = TreeMap<Option<TypeId>, Arc<(HighlightStyle, Vec<DocumentRange>)>>;
 
 pub struct DisplayMap {
     buffer: ModelHandle<MultiBuffer>,
@@ -211,11 +215,28 @@ impl DisplayMap {
         ranges: Vec<Range<Anchor>>,
         style: HighlightStyle,
     ) {
-        self.text_highlights
-            .insert(Some(type_id), Arc::new((style, ranges)));
+        self.text_highlights.insert(
+            Some(type_id),
+            Arc::new((style, ranges.into_iter().map(DocumentRange::Text).collect())),
+        );
     }
 
-    pub fn text_highlights(&self, type_id: TypeId) -> Option<(HighlightStyle, &[Range<Anchor>])> {
+    pub fn highlight_inlays(
+        &mut self,
+        type_id: TypeId,
+        ranges: Vec<InlayRange>,
+        style: HighlightStyle,
+    ) {
+        self.text_highlights.insert(
+            Some(type_id),
+            Arc::new((
+                style,
+                ranges.into_iter().map(DocumentRange::Inlay).collect(),
+            )),
+        );
+    }
+
+    pub fn text_highlights(&self, type_id: TypeId) -> Option<(HighlightStyle, &[DocumentRange])> {
         let highlights = self.text_highlights.get(&Some(type_id))?;
         Some((highlights.0, &highlights.1))
     }
@@ -223,7 +244,7 @@ impl DisplayMap {
     pub fn clear_text_highlights(
         &mut self,
         type_id: TypeId,
-    ) -> Option<Arc<(HighlightStyle, Vec<Range<Anchor>>)>> {
+    ) -> Option<Arc<(HighlightStyle, Vec<DocumentRange>)>> {
         self.text_highlights.remove(&Some(type_id))
     }
 
@@ -290,7 +311,7 @@ impl DisplayMap {
 
 pub struct DisplaySnapshot {
     pub buffer_snapshot: MultiBufferSnapshot,
-    fold_snapshot: fold_map::FoldSnapshot,
+    pub fold_snapshot: fold_map::FoldSnapshot,
     inlay_snapshot: inlay_map::InlaySnapshot,
     tab_snapshot: tab_map::TabSnapshot,
     wrap_snapshot: wrap_map::WrapSnapshot,
@@ -387,12 +408,49 @@ impl DisplaySnapshot {
     }
 
     fn display_point_to_point(&self, point: DisplayPoint, bias: Bias) -> Point {
+        self.inlay_snapshot
+            .to_buffer_point(self.display_point_to_inlay_point(point, bias))
+    }
+
+    pub fn display_point_to_inlay_offset(&self, point: DisplayPoint, bias: Bias) -> InlayOffset {
+        self.inlay_snapshot
+            .to_offset(self.display_point_to_inlay_point(point, bias))
+    }
+
+    pub fn anchor_to_inlay_offset(&self, anchor: Anchor) -> InlayOffset {
+        self.inlay_snapshot
+            .to_inlay_offset(anchor.to_offset(&self.buffer_snapshot))
+    }
+
+    pub fn inlay_offset_to_display_point(&self, offset: InlayOffset, bias: Bias) -> DisplayPoint {
+        let inlay_point = self.inlay_snapshot.to_point(offset);
+        let fold_point = self.fold_snapshot.to_fold_point(inlay_point, bias);
+        let tab_point = self.tab_snapshot.to_tab_point(fold_point);
+        let wrap_point = self.wrap_snapshot.tab_point_to_wrap_point(tab_point);
+        let block_point = self.block_snapshot.to_block_point(wrap_point);
+        DisplayPoint(block_point)
+    }
+
+    fn display_point_to_inlay_point(&self, point: DisplayPoint, bias: Bias) -> InlayPoint {
         let block_point = point.0;
         let wrap_point = self.block_snapshot.to_wrap_point(block_point);
         let tab_point = self.wrap_snapshot.to_tab_point(wrap_point);
         let fold_point = self.tab_snapshot.to_fold_point(tab_point, bias).0;
-        let inlay_point = fold_point.to_inlay_point(&self.fold_snapshot);
-        self.inlay_snapshot.to_buffer_point(inlay_point)
+        fold_point.to_inlay_point(&self.fold_snapshot)
+    }
+
+    pub fn display_point_to_fold_point(&self, point: DisplayPoint, bias: Bias) -> FoldPoint {
+        let block_point = point.0;
+        let wrap_point = self.block_snapshot.to_wrap_point(block_point);
+        let tab_point = self.wrap_snapshot.to_tab_point(wrap_point);
+        self.tab_snapshot.to_fold_point(tab_point, bias).0
+    }
+
+    pub fn fold_point_to_display_point(&self, fold_point: FoldPoint) -> DisplayPoint {
+        let tab_point = self.tab_snapshot.to_tab_point(fold_point);
+        let wrap_point = self.wrap_snapshot.tab_point_to_wrap_point(tab_point);
+        let block_point = self.block_snapshot.to_block_point(wrap_point);
+        DisplayPoint(block_point)
     }
 
     pub fn max_point(&self) -> DisplayPoint {
@@ -428,15 +486,15 @@ impl DisplaySnapshot {
         &self,
         display_rows: Range<u32>,
         language_aware: bool,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> DisplayChunks<'_> {
         self.block_snapshot.chunks(
             display_rows,
             language_aware,
             Some(&self.text_highlights),
-            hint_highlights,
-            suggestion_highlights,
+            hint_highlight_style,
+            suggestion_highlight_style,
         )
     }
 
@@ -757,7 +815,7 @@ impl DisplaySnapshot {
     #[cfg(any(test, feature = "test-support"))]
     pub fn highlight_ranges<Tag: ?Sized + 'static>(
         &self,
-    ) -> Option<Arc<(HighlightStyle, Vec<Range<Anchor>>)>> {
+    ) -> Option<Arc<(HighlightStyle, Vec<DocumentRange>)>> {
         let type_id = TypeId::of::<Tag>();
         self.text_highlights.get(&Some(type_id)).cloned()
     }
@@ -1319,7 +1377,8 @@ pub mod tests {
 
         cx.update(|cx| init_test(cx, |s| s.defaults.tab_size = Some(2.try_into().unwrap())));
 
-        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+        let buffer = cx
+            .add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
         buffer.condition(cx, |buf, _| !buf.is_parsing()).await;
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
 
@@ -1408,7 +1467,8 @@ pub mod tests {
 
         cx.update(|cx| init_test(cx, |_| {}));
 
-        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+        let buffer = cx
+            .add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
         buffer.condition(cx, |buf, _| !buf.is_parsing()).await;
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
 
@@ -1480,7 +1540,8 @@ pub mod tests {
 
         let (text, highlighted_ranges) = marked_text_ranges(r#"constˇ «a»: B = "c «d»""#, false);
 
-        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+        let buffer = cx
+            .add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
         buffer.condition(cx, |buf, _| !buf.is_parsing()).await;
 
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));

crates/editor/src/display_map/block_map.rs

@@ -589,8 +589,8 @@ impl BlockSnapshot {
         rows: Range<u32>,
         language_aware: bool,
         text_highlights: Option<&'a TextHighlights>,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> BlockChunks<'a> {
         let max_output_row = cmp::min(rows.end, self.transforms.summary().output_rows);
         let mut cursor = self.transforms.cursor::<(BlockRow, WrapRow)>();
@@ -623,8 +623,8 @@ impl BlockSnapshot {
                 input_start..input_end,
                 language_aware,
                 text_highlights,
-                hint_highlights,
-                suggestion_highlights,
+                hint_highlight_style,
+                suggestion_highlight_style,
             ),
             input_chunk: Default::default(),
             transforms: cursor,

crates/editor/src/display_map/fold_map.rs

@@ -652,8 +652,8 @@ impl FoldSnapshot {
         range: Range<FoldOffset>,
         language_aware: bool,
         text_highlights: Option<&'a TextHighlights>,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> FoldChunks<'a> {
         let mut transform_cursor = self.transforms.cursor::<(FoldOffset, InlayOffset)>();
 
@@ -675,8 +675,8 @@ impl FoldSnapshot {
                 inlay_start..inlay_end,
                 language_aware,
                 text_highlights,
-                hint_highlights,
-                suggestion_highlights,
+                hint_highlight_style,
+                suggestion_highlight_style,
             ),
             inlay_chunk: None,
             inlay_offset: inlay_start,

crates/editor/src/display_map/inlay_map.rs

@@ -1,4 +1,5 @@
 use crate::{
+    link_go_to_definition::DocumentRange,
     multi_buffer::{MultiBufferChunks, MultiBufferRows},
     Anchor, InlayId, MultiBufferSnapshot, ToOffset,
 };
@@ -183,7 +184,7 @@ pub struct InlayBufferRows<'a> {
     max_buffer_row: u32,
 }
 
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
 struct HighlightEndpoint {
     offset: InlayOffset,
     is_start: bool,
@@ -210,6 +211,7 @@ pub struct InlayChunks<'a> {
     buffer_chunks: MultiBufferChunks<'a>,
     buffer_chunk: Option<Chunk<'a>>,
     inlay_chunks: Option<text::Chunks<'a>>,
+    inlay_chunk: Option<&'a str>,
     output_offset: InlayOffset,
     max_output_offset: InlayOffset,
     hint_highlight_style: Option<HighlightStyle>,
@@ -297,13 +299,31 @@ impl<'a> Iterator for InlayChunks<'a> {
                         - self.transforms.start().0;
                     inlay.text.chunks_in_range(start.0..end.0)
                 });
+                let inlay_chunk = self
+                    .inlay_chunk
+                    .get_or_insert_with(|| inlay_chunks.next().unwrap());
+                let (chunk, remainder) = inlay_chunk.split_at(
+                    inlay_chunk
+                        .len()
+                        .min(next_highlight_endpoint.0 - self.output_offset.0),
+                );
+                *inlay_chunk = remainder;
+                if inlay_chunk.is_empty() {
+                    self.inlay_chunk = None;
+                }
 
-                let chunk = inlay_chunks.next().unwrap();
                 self.output_offset.0 += chunk.len();
-                let highlight_style = match inlay.id {
+                let mut highlight_style = match inlay.id {
                     InlayId::Suggestion(_) => self.suggestion_highlight_style,
                     InlayId::Hint(_) => self.hint_highlight_style,
                 };
+                if !self.active_highlights.is_empty() {
+                    for active_highlight in self.active_highlights.values() {
+                        highlight_style
+                            .get_or_insert(Default::default())
+                            .highlight(*active_highlight);
+                    }
+                }
                 Chunk {
                     text: chunk,
                     highlight_style,
@@ -973,8 +993,8 @@ impl InlaySnapshot {
         range: Range<InlayOffset>,
         language_aware: bool,
         text_highlights: Option<&'a TextHighlights>,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> InlayChunks<'a> {
         let mut cursor = self.transforms.cursor::<(InlayOffset, usize)>();
         cursor.seek(&range.start, Bias::Right, &());
@@ -983,10 +1003,11 @@ impl InlaySnapshot {
         if let Some(text_highlights) = text_highlights {
             if !text_highlights.is_empty() {
                 while cursor.start().0 < range.end {
-                    if true {
                     let transform_start = self.buffer.anchor_after(
                         self.to_buffer_offset(cmp::max(range.start, cursor.start().0)),
                     );
+                    let transform_start =
+                        self.to_inlay_offset(transform_start.to_offset(&self.buffer));
 
                     let transform_end = {
                         let overshoot = InlayOffset(range.end.0 - cursor.start().0 .0);
@@ -995,13 +1016,17 @@ impl InlaySnapshot {
                             cursor.start().0 + overshoot,
                         )))
                     };
+                    let transform_end = self.to_inlay_offset(transform_end.to_offset(&self.buffer));
 
-                        for (tag, highlights) in text_highlights.iter() {
-                            let style = highlights.0;
-                            let ranges = &highlights.1;
+                    for (tag, text_highlights) in text_highlights.iter() {
+                        let style = text_highlights.0;
+                        let ranges = &text_highlights.1;
 
                         let start_ix = match ranges.binary_search_by(|probe| {
-                                let cmp = probe.end.cmp(&transform_start, &self.buffer);
+                            let cmp = self
+                                .document_to_inlay_range(probe)
+                                .end
+                                .cmp(&transform_start);
                             if cmp.is_gt() {
                                 cmp::Ordering::Greater
                             } else {
@@ -1011,26 +1036,25 @@ impl InlaySnapshot {
                             Ok(i) | Err(i) => i,
                         };
                         for range in &ranges[start_ix..] {
-                                if range.start.cmp(&transform_end, &self.buffer).is_ge() {
+                            let range = self.document_to_inlay_range(range);
+                            if range.start.cmp(&transform_end).is_ge() {
                                 break;
                             }
 
                             highlight_endpoints.push(HighlightEndpoint {
-                                    offset: self
-                                        .to_inlay_offset(range.start.to_offset(&self.buffer)),
+                                offset: range.start,
                                 is_start: true,
                                 tag: *tag,
                                 style,
                             });
                             highlight_endpoints.push(HighlightEndpoint {
-                                    offset: self.to_inlay_offset(range.end.to_offset(&self.buffer)),
+                                offset: range.end,
                                 is_start: false,
                                 tag: *tag,
                                 style,
                             });
                         }
                     }
-                    }
 
                     cursor.next(&());
                 }
@@ -1046,17 +1070,30 @@ impl InlaySnapshot {
             transforms: cursor,
             buffer_chunks,
             inlay_chunks: None,
+            inlay_chunk: None,
             buffer_chunk: None,
             output_offset: range.start,
             max_output_offset: range.end,
-            hint_highlight_style: hint_highlights,
-            suggestion_highlight_style: suggestion_highlights,
+            hint_highlight_style,
+            suggestion_highlight_style,
             highlight_endpoints: highlight_endpoints.into_iter().peekable(),
             active_highlights: Default::default(),
             snapshot: self,
         }
     }
 
+    fn document_to_inlay_range(&self, range: &DocumentRange) -> Range<InlayOffset> {
+        match range {
+            DocumentRange::Text(text_range) => {
+                self.to_inlay_offset(text_range.start.to_offset(&self.buffer))
+                    ..self.to_inlay_offset(text_range.end.to_offset(&self.buffer))
+            }
+            DocumentRange::Inlay(inlay_range) => {
+                inlay_range.highlight_start..inlay_range.highlight_end
+            }
+        }
+    }
+
     #[cfg(test)]
     pub fn text(&self) -> String {
         self.chunks(Default::default()..self.len(), false, None, None, None)
@@ -1107,13 +1144,12 @@ fn push_isomorphic(sum_tree: &mut SumTree<Transform>, summary: TextSummary) {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{InlayId, MultiBuffer};
+    use crate::{link_go_to_definition::InlayRange, InlayId, MultiBuffer};
     use gpui::AppContext;
-    use project::{InlayHint, InlayHintLabel};
+    use project::{InlayHint, InlayHintLabel, ResolveState};
     use rand::prelude::*;
     use settings::SettingsStore;
     use std::{cmp::Reverse, env, sync::Arc};
-    use sum_tree::TreeMap;
     use text::Patch;
     use util::post_inc;
 
@@ -1125,12 +1161,12 @@ mod tests {
                 Anchor::min(),
                 &InlayHint {
                     label: InlayHintLabel::String("a".to_string()),
-                    buffer_id: 0,
                     position: text::Anchor::default(),
                     padding_left: false,
                     padding_right: false,
                     tooltip: None,
                     kind: None,
+                    resolve_state: ResolveState::Resolved,
                 },
             )
             .text
@@ -1145,12 +1181,12 @@ mod tests {
                 Anchor::min(),
                 &InlayHint {
                     label: InlayHintLabel::String("a".to_string()),
-                    buffer_id: 0,
                     position: text::Anchor::default(),
                     padding_left: true,
                     padding_right: true,
                     tooltip: None,
                     kind: None,
+                    resolve_state: ResolveState::Resolved,
                 },
             )
             .text
@@ -1165,12 +1201,12 @@ mod tests {
                 Anchor::min(),
                 &InlayHint {
                     label: InlayHintLabel::String(" a ".to_string()),
-                    buffer_id: 0,
                     position: text::Anchor::default(),
                     padding_left: false,
                     padding_right: false,
                     tooltip: None,
                     kind: None,
+                    resolve_state: ResolveState::Resolved,
                 },
             )
             .text
@@ -1185,12 +1221,12 @@ mod tests {
                 Anchor::min(),
                 &InlayHint {
                     label: InlayHintLabel::String(" a ".to_string()),
-                    buffer_id: 0,
                     position: text::Anchor::default(),
                     padding_left: true,
                     padding_right: true,
                     tooltip: None,
                     kind: None,
+                    resolve_state: ResolveState::Resolved,
                 },
             )
             .text
@@ -1542,26 +1578,6 @@ mod tests {
         let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
         let mut next_inlay_id = 0;
         log::info!("buffer text: {:?}", buffer_snapshot.text());
-
-        let mut highlights = TreeMap::default();
-        let highlight_count = rng.gen_range(0_usize..10);
-        let mut highlight_ranges = (0..highlight_count)
-            .map(|_| buffer_snapshot.random_byte_range(0, &mut rng))
-            .collect::<Vec<_>>();
-        highlight_ranges.sort_by_key(|range| (range.start, Reverse(range.end)));
-        log::info!("highlighting ranges {:?}", highlight_ranges);
-        let highlight_ranges = highlight_ranges
-            .into_iter()
-            .map(|range| {
-                buffer_snapshot.anchor_before(range.start)..buffer_snapshot.anchor_after(range.end)
-            })
-            .collect::<Vec<_>>();
-
-        highlights.insert(
-            Some(TypeId::of::<()>()),
-            Arc::new((HighlightStyle::default(), highlight_ranges)),
-        );
-
         let (mut inlay_map, mut inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
         for _ in 0..operations {
             let mut inlay_edits = Patch::default();
@@ -1624,6 +1640,38 @@ mod tests {
                 );
             }
 
+            let mut highlights = TextHighlights::default();
+            let highlight_count = rng.gen_range(0_usize..10);
+            let mut highlight_ranges = (0..highlight_count)
+                .map(|_| buffer_snapshot.random_byte_range(0, &mut rng))
+                .collect::<Vec<_>>();
+            highlight_ranges.sort_by_key(|range| (range.start, Reverse(range.end)));
+            log::info!("highlighting ranges {:?}", highlight_ranges);
+            let highlight_ranges = if rng.gen_bool(0.5) {
+                highlight_ranges
+                    .into_iter()
+                    .map(|range| InlayRange {
+                        inlay_position: buffer_snapshot.anchor_before(range.start),
+                        highlight_start: inlay_snapshot.to_inlay_offset(range.start),
+                        highlight_end: inlay_snapshot.to_inlay_offset(range.end),
+                    })
+                    .map(DocumentRange::Inlay)
+                    .collect::<Vec<_>>()
+            } else {
+                highlight_ranges
+                    .into_iter()
+                    .map(|range| {
+                        buffer_snapshot.anchor_before(range.start)
+                            ..buffer_snapshot.anchor_after(range.end)
+                    })
+                    .map(DocumentRange::Text)
+                    .collect::<Vec<_>>()
+            };
+            highlights.insert(
+                Some(TypeId::of::<()>()),
+                Arc::new((HighlightStyle::default(), highlight_ranges)),
+            );
+
             for _ in 0..5 {
                 let mut end = rng.gen_range(0..=inlay_snapshot.len().0);
                 end = expected_text.clip_offset(end, Bias::Right);

crates/editor/src/display_map/tab_map.rs

@@ -224,8 +224,8 @@ impl TabSnapshot {
         range: Range<TabPoint>,
         language_aware: bool,
         text_highlights: Option<&'a TextHighlights>,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> TabChunks<'a> {
         let (input_start, expanded_char_column, to_next_stop) =
             self.to_fold_point(range.start, Bias::Left);
@@ -246,8 +246,8 @@ impl TabSnapshot {
                 input_start..input_end,
                 language_aware,
                 text_highlights,
-                hint_highlights,
-                suggestion_highlights,
+                hint_highlight_style,
+                suggestion_highlight_style,
             ),
             input_column,
             column: expanded_char_column,

crates/editor/src/display_map/wrap_map.rs

@@ -576,8 +576,8 @@ impl WrapSnapshot {
         rows: Range<u32>,
         language_aware: bool,
         text_highlights: Option<&'a TextHighlights>,
-        hint_highlights: Option<HighlightStyle>,
-        suggestion_highlights: Option<HighlightStyle>,
+        hint_highlight_style: Option<HighlightStyle>,
+        suggestion_highlight_style: Option<HighlightStyle>,
     ) -> WrapChunks<'a> {
         let output_start = WrapPoint::new(rows.start, 0);
         let output_end = WrapPoint::new(rows.end, 0);
@@ -595,8 +595,8 @@ impl WrapSnapshot {
                 input_start..input_end,
                 language_aware,
                 text_highlights,
-                hint_highlights,
-                suggestion_highlights,
+                hint_highlight_style,
+                suggestion_highlight_style,
             ),
             input_chunk: Default::default(),
             output_position: output_start,

crates/editor/src/editor.rs

@@ -23,7 +23,7 @@ pub mod test;
 
 use ::git::diff::DiffHunk;
 use aho_corasick::AhoCorasick;
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use blink_manager::BlinkManager;
 use client::{ClickhouseEvent, TelemetrySettings};
 use clock::{Global, ReplicaId};
@@ -60,21 +60,24 @@ use itertools::Itertools;
 pub use language::{char_kind, CharKind};
 use language::{
     language_settings::{self, all_language_settings, InlayHintSettings},
-    AutoindentMode, BracketPair, Buffer, CodeAction, CodeLabel, Completion, CursorShape,
-    Diagnostic, DiagnosticSeverity, File, IndentKind, IndentSize, Language, OffsetRangeExt,
-    OffsetUtf16, Point, Selection, SelectionGoal, TransactionId,
+    point_from_lsp, AutoindentMode, BracketPair, Buffer, CodeAction, CodeLabel, Completion,
+    CursorShape, Diagnostic, DiagnosticSeverity, File, IndentKind, IndentSize, Language,
+    LanguageServerName, OffsetRangeExt, OffsetUtf16, Point, Selection, SelectionGoal,
+    TransactionId,
 };
 use link_go_to_definition::{
-    hide_link_definition, show_link_definition, LinkDefinitionKind, LinkGoToDefinitionState,
+    hide_link_definition, show_link_definition, DocumentRange, GoToDefinitionLink, InlayRange,
+    LinkGoToDefinitionState,
 };
 use log::error;
+use lsp::LanguageServerId;
 use multi_buffer::ToOffsetUtf16;
 pub use multi_buffer::{
     Anchor, AnchorRangeExt, ExcerptId, ExcerptRange, MultiBuffer, MultiBufferSnapshot, ToOffset,
     ToPoint,
 };
 use ordered_float::OrderedFloat;
-use project::{FormatTrigger, Location, LocationLink, Project, ProjectPath, ProjectTransaction};
+use project::{FormatTrigger, Location, Project, ProjectPath, ProjectTransaction};
 use rand::{seq::SliceRandom, thread_rng};
 use scroll::{
     autoscroll::Autoscroll, OngoingScroll, ScrollAnchor, ScrollManager, ScrollbarAutoHide,
@@ -108,6 +111,8 @@ const MAX_LINE_LEN: usize = 1024;
 const MIN_NAVIGATION_HISTORY_ROW_DELTA: i64 = 10;
 const MAX_SELECTION_HISTORY_LEN: usize = 1024;
 const COPILOT_DEBOUNCE_TIMEOUT: Duration = Duration::from_millis(75);
+pub const CODE_ACTIONS_DEBOUNCE_TIMEOUT: Duration = Duration::from_millis(250);
+pub const DOCUMENT_HIGHLIGHTS_DEBOUNCE_TIMEOUT: Duration = Duration::from_millis(75);
 
 pub const FORMAT_TIMEOUT: Duration = Duration::from_secs(2);
 
@@ -535,6 +540,8 @@ type CompletionId = usize;
 type GetFieldEditorTheme = dyn Fn(&theme::Theme) -> theme::FieldEditor;
 type OverrideTextStyle = dyn Fn(&EditorStyle) -> Option<HighlightStyle>;
 
+type BackgroundHighlight = (fn(&Theme) -> Color, Vec<DocumentRange>);
+
 pub struct Editor {
     handle: WeakViewHandle<Self>,
     buffer: ModelHandle<MultiBuffer>,
@@ -559,12 +566,12 @@ pub struct Editor {
     blink_manager: ModelHandle<BlinkManager>,
     show_local_selections: bool,
     mode: EditorMode,
+    replica_id_mapping: Option<HashMap<ReplicaId, ReplicaId>>,
     show_gutter: bool,
     show_wrap_guides: Option<bool>,
     placeholder_text: Option<Arc<str>>,
     highlighted_rows: Option<Range<u32>>,
-    #[allow(clippy::type_complexity)]
-    background_highlights: BTreeMap<TypeId, (fn(&Theme) -> Color, Vec<Range<Anchor>>)>,
+    background_highlights: BTreeMap<TypeId, BackgroundHighlight>,
     nav_history: Option<ItemNavHistory>,
     context_menu: Option<ContextMenu>,
     mouse_context_menu: ViewHandle<context_menu::ContextMenu>,
@@ -1246,6 +1253,19 @@ enum InlayHintRefreshReason {
     NewLinesShown,
     BufferEdited(HashSet<Arc<Language>>),
     RefreshRequested,
+    ExcerptsRemoved(Vec<ExcerptId>),
+}
+impl InlayHintRefreshReason {
+    fn description(&self) -> &'static str {
+        match self {
+            Self::Toggle(_) => "toggle",
+            Self::SettingsChange(_) => "settings change",
+            Self::NewLinesShown => "new lines shown",
+            Self::BufferEdited(_) => "buffer edited",
+            Self::RefreshRequested => "refresh requested",
+            Self::ExcerptsRemoved(_) => "excerpts removed",
+        }
+    }
 }
 
 impl Editor {
@@ -1253,7 +1273,7 @@ impl Editor {
         field_editor_style: Option<Arc<GetFieldEditorTheme>>,
         cx: &mut ViewContext<Self>,
     ) -> Self {
-        let buffer = cx.add_model(|cx| Buffer::new(0, String::new(), cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, String::new()));
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
         Self::new(EditorMode::SingleLine, buffer, None, field_editor_style, cx)
     }
@@ -1262,7 +1282,7 @@ impl Editor {
         field_editor_style: Option<Arc<GetFieldEditorTheme>>,
         cx: &mut ViewContext<Self>,
     ) -> Self {
-        let buffer = cx.add_model(|cx| Buffer::new(0, String::new(), cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, String::new()));
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
         Self::new(EditorMode::Full, buffer, None, field_editor_style, cx)
     }
@@ -1272,7 +1292,7 @@ impl Editor {
         field_editor_style: Option<Arc<GetFieldEditorTheme>>,
         cx: &mut ViewContext<Self>,
     ) -> Self {
-        let buffer = cx.add_model(|cx| Buffer::new(0, String::new(), cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, String::new()));
         let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
         Self::new(
             EditorMode::AutoHeight { max_lines },
@@ -1394,6 +1414,7 @@ impl Editor {
             blink_manager: blink_manager.clone(),
             show_local_selections: true,
             mode,
+            replica_id_mapping: None,
             show_gutter: mode == EditorMode::Full,
             show_wrap_guides: None,
             placeholder_text: None,
@@ -1604,6 +1625,19 @@ impl Editor {
         self.read_only = read_only;
     }
 
+    pub fn replica_id_map(&self) -> Option<&HashMap<ReplicaId, ReplicaId>> {
+        self.replica_id_mapping.as_ref()
+    }
+
+    pub fn set_replica_id_map(
+        &mut self,
+        mapping: Option<HashMap<ReplicaId, ReplicaId>>,
+        cx: &mut ViewContext<Self>,
+    ) {
+        self.replica_id_mapping = mapping;
+        cx.notify();
+    }
+
     fn selections_did_change(
         &mut self,
         local: bool,
@@ -2722,6 +2756,7 @@ impl Editor {
             return;
         }
 
+        let reason_description = reason.description();
         let (invalidate_cache, required_languages) = match reason {
             InlayHintRefreshReason::Toggle(enabled) => {
                 self.inlay_hint_cache.enabled = enabled;
@@ -2758,6 +2793,16 @@ impl Editor {
                     ControlFlow::Continue(()) => (InvalidationStrategy::RefreshRequested, None),
                 }
             }
+            InlayHintRefreshReason::ExcerptsRemoved(excerpts_removed) => {
+                if let Some(InlaySplice {
+                    to_remove,
+                    to_insert,
+                }) = self.inlay_hint_cache.remove_excerpts(excerpts_removed)
+                {
+                    self.splice_inlay_hints(to_remove, to_insert, cx);
+                }
+                return;
+            }
             InlayHintRefreshReason::NewLinesShown => (InvalidationStrategy::None, None),
             InlayHintRefreshReason::BufferEdited(buffer_languages) => {
                 (InvalidationStrategy::BufferEdited, Some(buffer_languages))
@@ -2771,6 +2816,7 @@ impl Editor {
             to_remove,
             to_insert,
         }) = self.inlay_hint_cache.spawn_hint_refresh(
+            reason_description,
             self.excerpt_visible_offsets(required_languages.as_ref(), cx),
             invalidate_cache,
             cx,
@@ -3248,7 +3294,7 @@ impl Editor {
     }
 
     fn refresh_code_actions(&mut self, cx: &mut ViewContext<Self>) -> Option<()> {
-        let project = self.project.as_ref()?;
+        let project = self.project.clone()?;
         let buffer = self.buffer.read(cx);
         let newest_selection = self.selections.newest_anchor().clone();
         let (start_buffer, start) = buffer.text_anchor_for_position(newest_selection.start, cx)?;
@@ -3257,11 +3303,15 @@ impl Editor {
             return None;
         }
 
-        let actions = project.update(cx, |project, cx| {
-            project.code_actions(&start_buffer, start..end, cx)
-        });
         self.code_actions_task = Some(cx.spawn(|this, mut cx| async move {
-            let actions = actions.await;
+            cx.background().timer(CODE_ACTIONS_DEBOUNCE_TIMEOUT).await;
+
+            let actions = project
+                .update(&mut cx, |project, cx| {
+                    project.code_actions(&start_buffer, start..end, cx)
+                })
+                .await;
+
             this.update(&mut cx, |this, cx| {
                 this.available_code_actions = actions.log_err().and_then(|actions| {
                     if actions.is_empty() {
@@ -3282,7 +3332,7 @@ impl Editor {
             return None;
         }
 
-        let project = self.project.as_ref()?;
+        let project = self.project.clone()?;
         let buffer = self.buffer.read(cx);
         let newest_selection = self.selections.newest_anchor().clone();
         let cursor_position = newest_selection.head();
@@ -3293,12 +3343,19 @@ impl Editor {
             return None;
         }
 
-        let highlights = project.update(cx, |project, cx| {
-            project.document_highlights(&cursor_buffer, cursor_buffer_position, cx)
-        });
-
         self.document_highlights_task = Some(cx.spawn(|this, mut cx| async move {
-            if let Some(highlights) = highlights.await.log_err() {
+            cx.background()
+                .timer(DOCUMENT_HIGHLIGHTS_DEBOUNCE_TIMEOUT)
+                .await;
+
+            let highlights = project
+                .update(&mut cx, |project, cx| {
+                    project.document_highlights(&cursor_buffer, cursor_buffer_position, cx)
+                })
+                .await
+                .log_err();
+
+            if let Some(highlights) = highlights {
                 this.update(&mut cx, |this, cx| {
                     if this.pending_rename.is_some() {
                         return;
@@ -6227,7 +6284,9 @@ impl Editor {
     ) {
         self.change_selections(Some(Autoscroll::fit()), cx, |s| {
             s.move_offsets_with(|snapshot, selection| {
-                let Some(enclosing_bracket_ranges) = snapshot.enclosing_bracket_ranges(selection.start..selection.end) else {
+                let Some(enclosing_bracket_ranges) =
+                    snapshot.enclosing_bracket_ranges(selection.start..selection.end)
+                else {
                     return;
                 };
 
@@ -6239,7 +6298,8 @@ impl Editor {
                     let close = close.to_inclusive();
                     let length = close.end() - open.start;
                     let inside = selection.start >= open.end && selection.end <= *close.start();
-                    let in_bracket_range = open.to_inclusive().contains(&selection.head()) || close.contains(&selection.head());
+                    let in_bracket_range = open.to_inclusive().contains(&selection.head())
+                        || close.contains(&selection.head());
 
                     // If best is next to a bracket and current isn't, skip
                     if !in_bracket_range && best_in_bracket_range {
@@ -6254,7 +6314,8 @@ impl Editor {
                     best_length = length;
                     best_inside = inside;
                     best_in_bracket_range = in_bracket_range;
-                    best_destination = Some(if close.contains(&selection.start) && close.contains(&selection.end) {
+                    best_destination = Some(
+                        if close.contains(&selection.start) && close.contains(&selection.end) {
                             if inside {
                                 open.end
                             } else {
@@ -6266,7 +6327,8 @@ impl Editor {
                             } else {
                                 *close.end()
                             }
-                    });
+                        },
+                    );
                 }
 
                 if let Some(destination) = best_destination {
@@ -6510,7 +6572,9 @@ impl Editor {
         split: bool,
         cx: &mut ViewContext<Self>,
     ) {
-        let Some(workspace) = self.workspace(cx) else { return };
+        let Some(workspace) = self.workspace(cx) else {
+            return;
+        };
         let buffer = self.buffer.read(cx);
         let head = self.selections.newest::<usize>(cx).head();
         let (buffer, head) = if let Some(text_anchor) = buffer.text_anchor_for_position(head, cx) {
@@ -6528,7 +6592,14 @@ impl Editor {
         cx.spawn_labeled("Fetching Definition...", |editor, mut cx| async move {
             let definitions = definitions.await?;
             editor.update(&mut cx, |editor, cx| {
-                editor.navigate_to_definitions(definitions, split, cx);
+                editor.navigate_to_definitions(
+                    definitions
+                        .into_iter()
+                        .map(GoToDefinitionLink::Text)
+                        .collect(),
+                    split,
+                    cx,
+                );
             })?;
             Ok::<(), anyhow::Error>(())
         })
@@ -6537,53 +6608,74 @@ impl Editor {
 
     pub fn navigate_to_definitions(
         &mut self,
-        mut definitions: Vec<LocationLink>,
+        mut definitions: Vec<GoToDefinitionLink>,
         split: bool,
         cx: &mut ViewContext<Editor>,
     ) {
-        let Some(workspace) = self.workspace(cx) else { return };
+        let Some(workspace) = self.workspace(cx) else {
+            return;
+        };
         let pane = workspace.read(cx).active_pane().clone();
         // If there is one definition, just open it directly
         if definitions.len() == 1 {
             let definition = definitions.pop().unwrap();
-            let range = definition
-                .target
-                .range
-                .to_offset(definition.target.buffer.read(cx));
-
-            let range = self.range_for_match(&range);
-            if Some(&definition.target.buffer) == self.buffer.read(cx).as_singleton().as_ref() {
-                self.change_selections(Some(Autoscroll::fit()), cx, |s| {
+            let target_task = match definition {
+                GoToDefinitionLink::Text(link) => Task::Ready(Some(Ok(Some(link.target)))),
+                GoToDefinitionLink::InlayHint(lsp_location, server_id) => {
+                    self.compute_target_location(lsp_location, server_id, cx)
+                }
+            };
+            cx.spawn(|editor, mut cx| async move {
+                let target = target_task.await.context("target resolution task")?;
+                if let Some(target) = target {
+                    editor.update(&mut cx, |editor, cx| {
+                        let range = target.range.to_offset(target.buffer.read(cx));
+                        let range = editor.range_for_match(&range);
+                        if Some(&target.buffer) == editor.buffer.read(cx).as_singleton().as_ref() {
+                            editor.change_selections(Some(Autoscroll::fit()), cx, |s| {
                                 s.select_ranges([range]);
                             });
                         } else {
                             cx.window_context().defer(move |cx| {
-                    let target_editor: ViewHandle<Self> = workspace.update(cx, |workspace, cx| {
+                                let target_editor: ViewHandle<Self> =
+                                    workspace.update(cx, |workspace, cx| {
                                         if split {
-                            workspace.split_project_item(definition.target.buffer.clone(), cx)
+                                            workspace.split_project_item(target.buffer.clone(), cx)
                                         } else {
-                            workspace.open_project_item(definition.target.buffer.clone(), cx)
+                                            workspace.open_project_item(target.buffer.clone(), cx)
                                         }
                                     });
                                 target_editor.update(cx, |target_editor, cx| {
                                     // When selecting a definition in a different buffer, disable the nav history
                                     // to avoid creating a history entry at the previous cursor location.
                                     pane.update(cx, |pane, _| pane.disable_history());
-                        target_editor.change_selections(Some(Autoscroll::fit()), cx, |s| {
+                                    target_editor.change_selections(
+                                        Some(Autoscroll::fit()),
+                                        cx,
+                                        |s| {
                                             s.select_ranges([range]);
-                        });
+                                        },
+                                    );
                                     pane.update(cx, |pane, _| pane.enable_history());
                                 });
                             });
                         }
+                    })
+                } else {
+                    Ok(())
+                }
+            })
+            .detach_and_log_err(cx);
         } else if !definitions.is_empty() {
             let replica_id = self.replica_id(cx);
-            cx.window_context().defer(move |cx| {
+            cx.spawn(|editor, mut cx| async move {
+                let (title, location_tasks) = editor
+                    .update(&mut cx, |editor, cx| {
                         let title = definitions
                             .iter()
-                    .find(|definition| definition.origin.is_some())
-                    .and_then(|definition| {
-                        definition.origin.as_ref().map(|origin| {
+                            .find_map(|definition| match definition {
+                                GoToDefinitionLink::Text(link) => {
+                                    link.origin.as_ref().map(|origin| {
                                         let buffer = origin.buffer.read(cx);
                                         format!(
                                             "Definitions for {}",
@@ -6592,21 +6684,102 @@ impl Editor {
                                                 .collect::<String>()
                                         )
                                     })
+                                }
+                                GoToDefinitionLink::InlayHint(_, _) => None,
                             })
-                    .unwrap_or("Definitions".to_owned());
-                let locations = definitions
+                            .unwrap_or("Definitions".to_string());
+                        let location_tasks = definitions
                             .into_iter()
-                    .map(|definition| definition.target)
-                    .collect();
-                workspace.update(cx, |workspace, cx| {
+                            .map(|definition| match definition {
+                                GoToDefinitionLink::Text(link) => {
+                                    Task::Ready(Some(Ok(Some(link.target))))
+                                }
+                                GoToDefinitionLink::InlayHint(lsp_location, server_id) => {
+                                    editor.compute_target_location(lsp_location, server_id, cx)
+                                }
+                            })
+                            .collect::<Vec<_>>();
+                        (title, location_tasks)
+                    })
+                    .context("location tasks preparation")?;
+
+                let locations = futures::future::join_all(location_tasks)
+                    .await
+                    .into_iter()
+                    .filter_map(|location| location.transpose())
+                    .collect::<Result<_>>()
+                    .context("location tasks")?;
+                workspace.update(&mut cx, |workspace, cx| {
                     Self::open_locations_in_multibuffer(
                         workspace, locations, replica_id, title, split, cx,
                     )
                 });
-            });
+
+                anyhow::Ok(())
+            })
+            .detach_and_log_err(cx);
         }
     }
 
+    fn compute_target_location(
+        &self,
+        lsp_location: lsp::Location,
+        server_id: LanguageServerId,
+        cx: &mut ViewContext<Editor>,
+    ) -> Task<anyhow::Result<Option<Location>>> {
+        let Some(project) = self.project.clone() else {
+            return Task::Ready(Some(Ok(None)));
+        };
+
+        cx.spawn(move |editor, mut cx| async move {
+            let location_task = editor.update(&mut cx, |editor, cx| {
+                project.update(cx, |project, cx| {
+                    let language_server_name =
+                        editor.buffer.read(cx).as_singleton().and_then(|buffer| {
+                            project
+                                .language_server_for_buffer(buffer.read(cx), server_id, cx)
+                                .map(|(_, lsp_adapter)| {
+                                    LanguageServerName(Arc::from(lsp_adapter.name()))
+                                })
+                        });
+                    language_server_name.map(|language_server_name| {
+                        project.open_local_buffer_via_lsp(
+                            lsp_location.uri.clone(),
+                            server_id,
+                            language_server_name,
+                            cx,
+                        )
+                    })
+                })
+            })?;
+            let location = match location_task {
+                Some(task) => Some({
+                    let target_buffer_handle = task.await.context("open local buffer")?;
+                    let range = {
+                        target_buffer_handle.update(&mut cx, |target_buffer, _| {
+                            let target_start = target_buffer.clip_point_utf16(
+                                point_from_lsp(lsp_location.range.start),
+                                Bias::Left,
+                            );
+                            let target_end = target_buffer.clip_point_utf16(
+                                point_from_lsp(lsp_location.range.end),
+                                Bias::Left,
+                            );
+                            target_buffer.anchor_after(target_start)
+                                ..target_buffer.anchor_before(target_end)
+                        })
+                    };
+                    Location {
+                        buffer: target_buffer_handle,
+                        range,
+                    }
+                }),
+                None => None,
+            };
+            Ok(location)
+        })
+    }
+
     pub fn find_all_references(
         workspace: &mut Workspace,
         _: &FindAllReferences,
@@ -6742,10 +6915,18 @@ impl Editor {
             let rename_range = if let Some(range) = prepare_rename.await? {
                 Some(range)
             } else {
-                this.read_with(&cx, |this, cx| {
+                this.update(&mut cx, |this, cx| {
                     let buffer = this.buffer.read(cx).snapshot(cx);
+                    let display_snapshot = this
+                        .display_map
+                        .update(cx, |display_map, cx| display_map.snapshot(cx));
                     let mut buffer_highlights = this
-                        .document_highlights_for_position(selection.head(), &buffer)
+                        .document_highlights_for_position(
+                            selection.head(),
+                            &buffer,
+                            &display_snapshot,
+                        )
+                        .filter_map(|highlight| highlight.as_text_range())
                         .filter(|highlight| {
                             highlight.start.excerpt_id() == selection.head().excerpt_id()
                                 && highlight.end.excerpt_id() == selection.head().excerpt_id()
@@ -6800,11 +6981,15 @@ impl Editor {
                     let ranges = this
                         .clear_background_highlights::<DocumentHighlightWrite>(cx)
                         .into_iter()
-                        .flat_map(|(_, ranges)| ranges)
+                        .flat_map(|(_, ranges)| {
+                            ranges.into_iter().filter_map(|range| range.as_text_range())
+                        })
                         .chain(
                             this.clear_background_highlights::<DocumentHighlightRead>(cx)
                                 .into_iter()
-                                .flat_map(|(_, ranges)| ranges),
+                                .flat_map(|(_, ranges)| {
+                                    ranges.into_iter().filter_map(|range| range.as_text_range())
+                                }),
                         )
                         .collect();
 
@@ -7161,7 +7346,7 @@ impl Editor {
 
         let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
 
-        let selections = self.selections.all::<Point>(cx);
+        let selections = self.selections.all_adjusted(cx);
         for selection in selections {
             let range = selection.range().sorted();
             let buffer_start_row = range.start.row;
@@ -7237,7 +7422,17 @@ impl Editor {
 
     pub fn fold_selected_ranges(&mut self, _: &FoldSelectedRanges, cx: &mut ViewContext<Self>) {
         let selections = self.selections.all::<Point>(cx);
-        let ranges = selections.into_iter().map(|s| s.start..s.end);
+        let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
+        let line_mode = self.selections.line_mode;
+        let ranges = selections.into_iter().map(|s| {
+            if line_mode {
+                let start = Point::new(s.start.row, 0);
+                let end = Point::new(s.end.row, display_map.buffer_snapshot.line_len(s.end.row));
+                start..end
+            } else {
+                s.start..s.end
+            }
+        });
         self.fold_ranges(ranges, true, cx);
     }
 
@@ -7472,16 +7667,36 @@ impl Editor {
         color_fetcher: fn(&Theme) -> Color,
         cx: &mut ViewContext<Self>,
     ) {
-        self.background_highlights
-            .insert(TypeId::of::<T>(), (color_fetcher, ranges));
+        self.background_highlights.insert(
+            TypeId::of::<T>(),
+            (
+                color_fetcher,
+                ranges.into_iter().map(DocumentRange::Text).collect(),
+            ),
+        );
+        cx.notify();
+    }
+
+    pub fn highlight_inlay_background<T: 'static>(
+        &mut self,
+        ranges: Vec<InlayRange>,
+        color_fetcher: fn(&Theme) -> Color,
+        cx: &mut ViewContext<Self>,
+    ) {
+        self.background_highlights.insert(
+            TypeId::of::<T>(),
+            (
+                color_fetcher,
+                ranges.into_iter().map(DocumentRange::Inlay).collect(),
+            ),
+        );
         cx.notify();
     }
 
-    #[allow(clippy::type_complexity)]
     pub fn clear_background_highlights<T: 'static>(
         &mut self,
         cx: &mut ViewContext<Self>,
-    ) -> Option<(fn(&Theme) -> Color, Vec<Range<Anchor>>)> {
+    ) -> Option<BackgroundHighlight> {
         let highlights = self.background_highlights.remove(&TypeId::of::<T>());
         if highlights.is_some() {
             cx.notify();
@@ -7506,7 +7721,8 @@ impl Editor {
         &'a self,
         position: Anchor,
         buffer: &'a MultiBufferSnapshot,
-    ) -> impl 'a + Iterator<Item = &Range<Anchor>> {
+        display_snapshot: &'a DisplaySnapshot,
+    ) -> impl 'a + Iterator<Item = &DocumentRange> {
         let read_highlights = self
             .background_highlights
             .get(&TypeId::of::<DocumentHighlightRead>())
@@ -7515,14 +7731,16 @@ impl Editor {
             .background_highlights
             .get(&TypeId::of::<DocumentHighlightWrite>())
             .map(|h| &h.1);
-        let left_position = position.bias_left(buffer);
-        let right_position = position.bias_right(buffer);
+        let left_position = display_snapshot.anchor_to_inlay_offset(position.bias_left(buffer));
+        let right_position = display_snapshot.anchor_to_inlay_offset(position.bias_right(buffer));
         read_highlights
             .into_iter()
             .chain(write_highlights)
             .flat_map(move |ranges| {
                 let start_ix = match ranges.binary_search_by(|probe| {
-                    let cmp = probe.end.cmp(&left_position, buffer);
+                    let cmp = document_to_inlay_range(probe, display_snapshot)
+                        .end
+                        .cmp(&left_position);
                     if cmp.is_ge() {
                         Ordering::Greater
                     } else {
@@ -7533,9 +7751,12 @@ impl Editor {
                 };
 
                 let right_position = right_position.clone();
-                ranges[start_ix..]
-                    .iter()
-                    .take_while(move |range| range.start.cmp(&right_position, buffer).is_le())
+                ranges[start_ix..].iter().take_while(move |range| {
+                    document_to_inlay_range(range, display_snapshot)
+                        .start
+                        .cmp(&right_position)
+                        .is_le()
+                })
             })
     }
 
@@ -7545,12 +7766,15 @@ impl Editor {
         display_snapshot: &DisplaySnapshot,
         theme: &Theme,
     ) -> Vec<(Range<DisplayPoint>, Color)> {
+        let search_range = display_snapshot.anchor_to_inlay_offset(search_range.start)
+            ..display_snapshot.anchor_to_inlay_offset(search_range.end);
         let mut results = Vec::new();
-        let buffer = &display_snapshot.buffer_snapshot;
         for (color_fetcher, ranges) in self.background_highlights.values() {
             let color = color_fetcher(theme);
             let start_ix = match ranges.binary_search_by(|probe| {
-                let cmp = probe.end.cmp(&search_range.start, buffer);
+                let cmp = document_to_inlay_range(probe, display_snapshot)
+                    .end
+                    .cmp(&search_range.start);
                 if cmp.is_gt() {
                     Ordering::Greater
                 } else {
@@ -7560,63 +7784,18 @@ impl Editor {
                 Ok(i) | Err(i) => i,
             };
             for range in &ranges[start_ix..] {
-                if range.start.cmp(&search_range.end, buffer).is_ge() {
+                let range = document_to_inlay_range(range, display_snapshot);
+                if range.start.cmp(&search_range.end).is_ge() {
                     break;
                 }
-                let start = range
-                    .start
-                    .to_point(buffer)
-                    .to_display_point(display_snapshot);
-                let end = range
-                    .end
-                    .to_point(buffer)
-                    .to_display_point(display_snapshot);
+
+                let start = display_snapshot.inlay_offset_to_display_point(range.start, Bias::Left);
+                let end = display_snapshot.inlay_offset_to_display_point(range.end, Bias::Right);
                 results.push((start..end, color))
             }
         }
         results
     }
-    pub fn background_highlights_in_range_for<T: 'static>(
-        &self,
-        search_range: Range<Anchor>,
-        display_snapshot: &DisplaySnapshot,
-        theme: &Theme,
-    ) -> Vec<(Range<DisplayPoint>, Color)> {
-        let mut results = Vec::new();
-        let buffer = &display_snapshot.buffer_snapshot;
-        let Some((color_fetcher, ranges)) = self.background_highlights
-            .get(&TypeId::of::<T>()) else {
-                return vec![];
-            };
-
-        let color = color_fetcher(theme);
-        let start_ix = match ranges.binary_search_by(|probe| {
-            let cmp = probe.end.cmp(&search_range.start, buffer);
-            if cmp.is_gt() {
-                Ordering::Greater
-            } else {
-                Ordering::Less
-            }
-        }) {
-            Ok(i) | Err(i) => i,
-        };
-        for range in &ranges[start_ix..] {
-            if range.start.cmp(&search_range.end, buffer).is_ge() {
-                break;
-            }
-            let start = range
-                .start
-                .to_point(buffer)
-                .to_display_point(display_snapshot);
-            let end = range
-                .end
-                .to_point(buffer)
-                .to_display_point(display_snapshot);
-            results.push((start..end, color))
-        }
-
-        results
-    }
 
     pub fn background_highlight_row_ranges<T: 'static>(
         &self,
@@ -7624,15 +7803,17 @@ impl Editor {
         display_snapshot: &DisplaySnapshot,
         count: usize,
     ) -> Vec<RangeInclusive<DisplayPoint>> {
+        let search_range = display_snapshot.anchor_to_inlay_offset(search_range.start)
+            ..display_snapshot.anchor_to_inlay_offset(search_range.end);
         let mut results = Vec::new();
-        let buffer = &display_snapshot.buffer_snapshot;
-        let Some((_, ranges)) = self.background_highlights
-            .get(&TypeId::of::<T>()) else {
+        let Some((_, ranges)) = self.background_highlights.get(&TypeId::of::<T>()) else {
             return vec![];
         };
 
         let start_ix = match ranges.binary_search_by(|probe| {
-            let cmp = probe.end.cmp(&search_range.start, buffer);
+            let cmp = document_to_inlay_range(probe, display_snapshot)
+                .end
+                .cmp(&search_range.start);
             if cmp.is_gt() {
                 Ordering::Greater
             } else {
@@ -7652,19 +7833,24 @@ impl Editor {
         let mut start_row: Option<Point> = None;
         let mut end_row: Option<Point> = None;
         if ranges.len() > count {
-            return vec![];
+            return Vec::new();
         }
         for range in &ranges[start_ix..] {
-            if range.start.cmp(&search_range.end, buffer).is_ge() {
+            let range = document_to_inlay_range(range, display_snapshot);
+            if range.start.cmp(&search_range.end).is_ge() {
                 break;
             }
-            let end = range.end.to_point(buffer);
+            let end = display_snapshot
+                .inlay_offset_to_display_point(range.end, Bias::Right)
+                .to_point(display_snapshot);
             if let Some(current_row) = &end_row {
                 if end.row == current_row.row {
                     continue;
                 }
             }
-            let start = range.start.to_point(buffer);
+            let start = display_snapshot
+                .inlay_offset_to_display_point(range.start, Bias::Left)
+                .to_point(display_snapshot);
 
             if start_row.is_none() {
                 assert_eq!(end_row, None);
@@ -7702,24 +7888,32 @@ impl Editor {
         cx.notify();
     }
 
+    pub fn highlight_inlays<T: 'static>(
+        &mut self,
+        ranges: Vec<InlayRange>,
+        style: HighlightStyle,
+        cx: &mut ViewContext<Self>,
+    ) {
+        self.display_map.update(cx, |map, _| {
+            map.highlight_inlays(TypeId::of::<T>(), ranges, style)
+        });
+        cx.notify();
+    }
+
     pub fn text_highlights<'a, T: 'static>(
         &'a self,
         cx: &'a AppContext,
-    ) -> Option<(HighlightStyle, &'a [Range<Anchor>])> {
+    ) -> Option<(HighlightStyle, &'a [DocumentRange])> {
         self.display_map.read(cx).text_highlights(TypeId::of::<T>())
     }
 
-    pub fn clear_text_highlights<T: 'static>(
-        &mut self,
-        cx: &mut ViewContext<Self>,
-    ) -> Option<Arc<(HighlightStyle, Vec<Range<Anchor>>)>> {
-        let highlights = self
+    pub fn clear_text_highlights<T: 'static>(&mut self, cx: &mut ViewContext<Self>) {
+        let text_highlights = self
             .display_map
             .update(cx, |map, _| map.clear_text_highlights(TypeId::of::<T>()));
-        if highlights.is_some() {
+        if text_highlights.is_some() {
             cx.notify();
         }
-        highlights
     }
 
     pub fn show_local_cursors(&self, cx: &AppContext) -> bool {
@@ -7737,7 +7931,9 @@ impl Editor {
         cx: &mut ViewContext<Self>,
     ) {
         match event {
-            multi_buffer::Event::Edited => {
+            multi_buffer::Event::Edited {
+                sigleton_buffer_edited,
+            } => {
                 self.refresh_active_diagnostics(cx);
                 self.refresh_code_actions(cx);
                 if self.has_active_copilot_suggestion(cx) {
@@ -7745,6 +7941,7 @@ impl Editor {
                 }
                 cx.emit(Event::BufferEdited);
 
+                if *sigleton_buffer_edited {
                     if let Some(project) = &self.project {
                         let project = project.read(cx);
                         let languages_affected = multibuffer
@@ -7772,16 +7969,21 @@ impl Editor {
                         }
                     }
                 }
+            }
             multi_buffer::Event::ExcerptsAdded {
                 buffer,
                 predecessor,
                 excerpts,
-            } => cx.emit(Event::ExcerptsAdded {
+            } => {
+                cx.emit(Event::ExcerptsAdded {
                     buffer: buffer.clone(),
                     predecessor: *predecessor,
                     excerpts: excerpts.clone(),
-            }),
+                });
+                self.refresh_inlay_hints(InlayHintRefreshReason::NewLinesShown, cx);
+            }
             multi_buffer::Event::ExcerptsRemoved { ids } => {
+                self.refresh_inlay_hints(InlayHintRefreshReason::ExcerptsRemoved(ids.clone()), cx);
                 cx.emit(Event::ExcerptsRemoved { ids: ids.clone() })
             }
             multi_buffer::Event::Reparsed => cx.emit(Event::Reparsed),
@@ -7926,6 +8128,7 @@ impl Editor {
         Some(
             ranges
                 .iter()
+                .filter_map(|range| range.as_text_range())
                 .map(move |range| {
                     range.start.to_offset_utf16(&snapshot)..range.end.to_offset_utf16(&snapshot)
                 })
@@ -7964,9 +8167,7 @@ impl Editor {
         suggestion_accepted: bool,
         cx: &AppContext,
     ) {
-        let Some(project) = &self.project else {
-            return
-        };
+        let Some(project) = &self.project else { return };
 
         // If None, we are either getting suggestions in a new, unsaved file, or in a file without an extension
         let file_extension = self
@@ -7995,9 +8196,7 @@ impl Editor {
         file_extension: Option<String>,
         cx: &AppContext,
     ) {
-        let Some(project) = &self.project else {
-            return
-        };
+        let Some(project) = &self.project else { return };
 
         // If None, we are in a file without an extension
         let file = self
@@ -8098,7 +8297,9 @@ impl Editor {
             }
         }
 
-        let Some(lines) = serde_json::to_string_pretty(&lines).log_err() else { return; };
+        let Some(lines) = serde_json::to_string_pretty(&lines).log_err() else {
+            return;
+        };
         cx.write_to_clipboard(ClipboardItem::new(lines));
     }
 
@@ -8107,6 +8308,19 @@ impl Editor {
     }
 }
 
+fn document_to_inlay_range(
+    range: &DocumentRange,
+    snapshot: &DisplaySnapshot,
+) -> Range<InlayOffset> {
+    match range {
+        DocumentRange::Text(text_range) => {
+            snapshot.anchor_to_inlay_offset(text_range.start)
+                ..snapshot.anchor_to_inlay_offset(text_range.end)
+        }
+        DocumentRange::Inlay(inlay_range) => inlay_range.highlight_start..inlay_range.highlight_end,
+    }
+}
+
 fn inlay_hint_settings(
     location: Anchor,
     snapshot: &MultiBufferSnapshot,
@@ -8291,14 +8505,11 @@ impl View for Editor {
     ) -> bool {
         let pending_selection = self.has_pending_selection();
 
-        if let Some(point) = self.link_go_to_definition_state.last_mouse_location.clone() {
+        if let Some(point) = &self.link_go_to_definition_state.last_trigger_point {
             if event.cmd && !pending_selection {
+                let point = point.clone();
                 let snapshot = self.snapshot(cx);
-                let kind = if event.shift {
-                    LinkDefinitionKind::Type
-                } else {
-                    LinkDefinitionKind::Symbol
-                };
+                let kind = point.definition_kind(event.shift);
 
                 show_link_definition(kind, self, point, snapshot, cx);
                 return false;
@@ -8382,6 +8593,7 @@ impl View for Editor {
     fn marked_text_range(&self, cx: &AppContext) -> Option<Range<usize>> {
         let snapshot = self.buffer.read(cx).read(cx);
         let range = self.text_highlights::<InputComposition>(cx)?.1.get(0)?;
+        let range = range.as_text_range()?;
         Some(range.start.to_offset_utf16(&snapshot).0..range.end.to_offset_utf16(&snapshot).0)
     }
 

crates/editor/src/editor_settings.rs

@@ -9,6 +9,7 @@ pub struct EditorSettings {
     pub show_completions_on_input: bool,
     pub use_on_type_format: bool,
     pub scrollbar: Scrollbar,
+    pub relative_line_numbers: bool,
 }
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
@@ -34,6 +35,7 @@ pub struct EditorSettingsContent {
     pub show_completions_on_input: Option<bool>,
     pub use_on_type_format: Option<bool>,
     pub scrollbar: Option<ScrollbarContent>,
+    pub relative_line_numbers: Option<bool>,
 }
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]

crates/editor/src/editor_tests.rs

@@ -42,7 +42,7 @@ fn test_edit_events(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
     let buffer = cx.add_model(|cx| {
-        let mut buffer = language::Buffer::new(0, "123456", cx);
+        let mut buffer = language::Buffer::new(0, cx.model_id() as u64, "123456");
         buffer.set_group_interval(Duration::from_secs(1));
         buffer
     });
@@ -174,7 +174,7 @@ fn test_undo_redo_with_selection_restoration(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
     let mut now = Instant::now();
-    let buffer = cx.add_model(|cx| language::Buffer::new(0, "123456", cx));
+    let buffer = cx.add_model(|cx| language::Buffer::new(0, cx.model_id() as u64, "123456"));
     let group_interval = buffer.read_with(cx, |buffer, _| buffer.transaction_group_interval());
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let editor = cx
@@ -247,7 +247,7 @@ fn test_ime_composition(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
     let buffer = cx.add_model(|cx| {
-        let mut buffer = language::Buffer::new(0, "abcde", cx);
+        let mut buffer = language::Buffer::new(0, cx.model_id() as u64, "abcde");
         // Ensure automatic grouping doesn't occur.
         buffer.set_group_interval(Duration::ZERO);
         buffer
@@ -1434,6 +1434,74 @@ async fn test_scroll_page_up_page_down(cx: &mut gpui::TestAppContext) {
     });
 }
 
+#[gpui::test]
+async fn test_autoscroll(cx: &mut gpui::TestAppContext) {
+    init_test(cx, |_| {});
+    let mut cx = EditorTestContext::new(cx).await;
+
+    let line_height = cx.update_editor(|editor, cx| {
+        editor.set_vertical_scroll_margin(2, cx);
+        editor.style(cx).text.line_height(cx.font_cache())
+    });
+
+    let window = cx.window;
+    window.simulate_resize(vec2f(1000., 6.0 * line_height), &mut cx);
+
+    cx.set_state(
+        &r#"ˇone
+            two
+            three
+            four
+            five
+            six
+            seven
+            eight
+            nine
+            ten
+        "#,
+    );
+    cx.update_editor(|editor, cx| {
+        assert_eq!(editor.snapshot(cx).scroll_position(), vec2f(0., 0.0));
+    });
+
+    // Add a cursor below the visible area. Since both cursors cannot fit
+    // on screen, the editor autoscrolls to reveal the newest cursor, and
+    // allows the vertical scroll margin below that cursor.
+    cx.update_editor(|editor, cx| {
+        editor.change_selections(Some(Autoscroll::fit()), cx, |selections| {
+            selections.select_ranges([
+                Point::new(0, 0)..Point::new(0, 0),
+                Point::new(6, 0)..Point::new(6, 0),
+            ]);
+        })
+    });
+    cx.update_editor(|editor, cx| {
+        assert_eq!(editor.snapshot(cx).scroll_position(), vec2f(0., 3.0));
+    });
+
+    // Move down. The editor cursor scrolls down to track the newest cursor.
+    cx.update_editor(|editor, cx| {
+        editor.move_down(&Default::default(), cx);
+    });
+    cx.update_editor(|editor, cx| {
+        assert_eq!(editor.snapshot(cx).scroll_position(), vec2f(0., 4.0));
+    });
+
+    // Add a cursor above the visible area. Since both cursors fit on screen,
+    // the editor scrolls to show both.
+    cx.update_editor(|editor, cx| {
+        editor.change_selections(Some(Autoscroll::fit()), cx, |selections| {
+            selections.select_ranges([
+                Point::new(1, 0)..Point::new(1, 0),
+                Point::new(6, 0)..Point::new(6, 0),
+            ]);
+        })
+    });
+    cx.update_editor(|editor, cx| {
+        assert_eq!(editor.snapshot(cx).scroll_position(), vec2f(0., 1.0));
+    });
+}
+
 #[gpui::test]
 async fn test_move_page_up_page_down(cx: &mut gpui::TestAppContext) {
     init_test(cx, |_| {});
@@ -2213,10 +2281,12 @@ fn test_indent_outdent_with_excerpts(cx: &mut TestAppContext) {
         None,
     ));
 
-    let toml_buffer =
-        cx.add_model(|cx| Buffer::new(0, "a = 1\nb = 2\n", cx).with_language(toml_language, cx));
+    let toml_buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, "a = 1\nb = 2\n").with_language(toml_language, cx)
+    });
     let rust_buffer = cx.add_model(|cx| {
-        Buffer::new(0, "const c: usize = 3;\n", cx).with_language(rust_language, cx)
+        Buffer::new(0, cx.model_id() as u64, "const c: usize = 3;\n")
+            .with_language(rust_language, cx)
     });
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
@@ -3686,7 +3756,8 @@ async fn test_select_larger_smaller_syntax_node(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+    let buffer =
+        cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let view = cx.add_window(|cx| build_editor(buffer, cx)).root(cx);
     view.condition(cx, |view, cx| !view.buffer.read(cx).is_parsing(cx))
@@ -3849,7 +3920,8 @@ async fn test_autoindent_selections(cx: &mut gpui::TestAppContext) {
 
     let text = "fn a() {}";
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+    let buffer =
+        cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let editor = cx.add_window(|cx| build_editor(buffer, cx)).root(cx);
     editor
@@ -4412,7 +4484,8 @@ async fn test_surround_with_pair(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+    let buffer =
+        cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let view = cx.add_window(|cx| build_editor(buffer, cx)).root(cx);
     view.condition(cx, |view, cx| !view.buffer.read(cx).is_parsing(cx))
@@ -4560,7 +4633,8 @@ async fn test_delete_autoclose_pair(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+    let buffer =
+        cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let editor = cx.add_window(|cx| build_editor(buffer, cx)).root(cx);
     editor
@@ -5766,7 +5840,7 @@ async fn test_toggle_block_comment(cx: &mut gpui::TestAppContext) {
 fn test_editing_disjoint_excerpts(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(3, 4, 'a'), cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(3, 4, 'a')));
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
         multibuffer.push_excerpts(
@@ -5850,7 +5924,7 @@ fn test_editing_overlapping_excerpts(cx: &mut TestAppContext) {
             primary: None,
         }
     });
-    let buffer = cx.add_model(|cx| Buffer::new(0, initial_text, cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, initial_text));
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
         multibuffer.push_excerpts(buffer, excerpt_ranges, cx);
@@ -5908,7 +5982,7 @@ fn test_editing_overlapping_excerpts(cx: &mut TestAppContext) {
 fn test_refresh_selections(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(3, 4, 'a'), cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(3, 4, 'a')));
     let mut excerpt1_id = None;
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
@@ -5995,7 +6069,7 @@ fn test_refresh_selections(cx: &mut TestAppContext) {
 fn test_refresh_selections_while_selecting_with_mouse(cx: &mut TestAppContext) {
     init_test(cx, |_| {});
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(3, 4, 'a'), cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(3, 4, 'a')));
     let mut excerpt1_id = None;
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
@@ -6092,7 +6166,8 @@ async fn test_extra_newline_insertion(cx: &mut gpui::TestAppContext) {
         "{{} }\n",     //
     );
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(language, cx));
+    let buffer =
+        cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text).with_language(language, cx));
     let buffer = cx.add_model(|cx| MultiBuffer::singleton(buffer, cx));
     let view = cx.add_window(|cx| build_editor(buffer, cx)).root(cx);
     view.condition(cx, |view, cx| !view.buffer.read(cx).is_parsing(cx))
@@ -6384,7 +6459,7 @@ async fn test_following_with_multiple_excerpts(cx: &mut gpui::TestAppContext) {
         .update(|cx| {
             Editor::from_state_proto(
                 pane.clone(),
-                project.clone(),
+                workspace.clone(),
                 ViewId {
                     creator: Default::default(),
                     id: 0,
@@ -6479,7 +6554,7 @@ async fn test_following_with_multiple_excerpts(cx: &mut gpui::TestAppContext) {
         .update(|cx| {
             Editor::from_state_proto(
                 pane.clone(),
-                project.clone(),
+                workspace.clone(),
                 ViewId {
                     creator: Default::default(),
                     id: 0,
@@ -7092,8 +7167,8 @@ async fn test_copilot_multibuffer(
     let (copilot, copilot_lsp) = Copilot::fake(cx);
     cx.update(|cx| cx.set_global(copilot));
 
-    let buffer_1 = cx.add_model(|cx| Buffer::new(0, "a = 1\nb = 2\n", cx));
-    let buffer_2 = cx.add_model(|cx| Buffer::new(0, "c = 3\nd = 4\n", cx));
+    let buffer_1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "a = 1\nb = 2\n"));
+    let buffer_2 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "c = 3\nd = 4\n"));
     let multibuffer = cx.add_model(|cx| {
         let mut multibuffer = MultiBuffer::new(0);
         multibuffer.push_excerpts(

crates/editor/src/element.rs

@@ -13,6 +13,7 @@ use crate::{
     },
     link_go_to_definition::{
         go_to_fetched_definition, go_to_fetched_type_definition, update_go_to_definition_link,
+        update_inlay_link_and_hover_points, GoToDefinitionTrigger,
     },
     mouse_context_menu, EditorSettings, EditorStyle, GutterHover, UnfoldAt,
 };
@@ -62,6 +63,7 @@ struct SelectionLayout {
     head: DisplayPoint,
     cursor_shape: CursorShape,
     is_newest: bool,
+    is_local: bool,
     range: Range<DisplayPoint>,
     active_rows: Range<u32>,
 }
@@ -73,6 +75,7 @@ impl SelectionLayout {
         cursor_shape: CursorShape,
         map: &DisplaySnapshot,
         is_newest: bool,
+        is_local: bool,
     ) -> Self {
         let point_selection = selection.map(|p| p.to_point(&map.buffer_snapshot));
         let display_selection = point_selection.map(|p| p.to_display_point(map));
@@ -109,6 +112,7 @@ impl SelectionLayout {
             head,
             cursor_shape,
             is_newest,
+            is_local,
             range,
             active_rows,
         }
@@ -284,13 +288,13 @@ impl EditorElement {
             return false;
         }
 
-        let (position, target_position) = position_map.point_for_position(text_bounds, position);
-
+        let point_for_position = position_map.point_for_position(text_bounds, position);
+        let position = point_for_position.previous_valid;
         if shift && alt {
             editor.select(
                 SelectPhase::BeginColumnar {
                     position,
-                    goal_column: target_position.column(),
+                    goal_column: point_for_position.exact_unclipped.column(),
                 },
                 cx,
             );
@@ -326,9 +330,13 @@ impl EditorElement {
         if !text_bounds.contains_point(position) {
             return false;
         }
-
-        let (point, _) = position_map.point_for_position(text_bounds, position);
-        mouse_context_menu::deploy_context_menu(editor, position, point, cx);
+        let point_for_position = position_map.point_for_position(text_bounds, position);
+        mouse_context_menu::deploy_context_menu(
+            editor,
+            position,
+            point_for_position.previous_valid,
+            cx,
+        );
         true
     }
 
@@ -350,10 +358,9 @@ impl EditorElement {
         }
 
         if !pending_nonempty_selections && cmd && text_bounds.contains_point(position) {
-            let (point, target_point) = position_map.point_for_position(text_bounds, position);
-
-            if point == target_point {
-                if shift {
+            let point = position_map.point_for_position(text_bounds, position);
+            let could_be_inlay = point.as_valid().is_none();
+            if shift || could_be_inlay {
                 go_to_fetched_type_definition(editor, point, alt, cx);
             } else {
                 go_to_fetched_definition(editor, point, alt, cx);
@@ -361,7 +368,6 @@ impl EditorElement {
 
             return true;
         }
-        }
 
         end_selection
     }
@@ -380,17 +386,20 @@ impl EditorElement {
         // This will be handled more correctly once https://github.com/zed-industries/zed/issues/1218 is completed
         // Don't trigger hover popover if mouse is hovering over context menu
         let point = if text_bounds.contains_point(position) {
-            let (point, target_point) = position_map.point_for_position(text_bounds, position);
-            if point == target_point {
-                Some(point)
-            } else {
-                None
-            }
+            position_map
+                .point_for_position(text_bounds, position)
+                .as_valid()
         } else {
             None
         };
 
-        update_go_to_definition_link(editor, point, cmd, shift, cx);
+        update_go_to_definition_link(
+            editor,
+            point.map(GoToDefinitionTrigger::Text),
+            cmd,
+            shift,
+            cx,
+        );
 
         if editor.has_pending_selection() {
             let mut scroll_delta = Vector2F::zero();
@@ -419,13 +428,12 @@ impl EditorElement {
                 ))
             }
 
-            let (position, target_position) =
-                position_map.point_for_position(text_bounds, position);
+            let point_for_position = position_map.point_for_position(text_bounds, position);
 
             editor.select(
                 SelectPhase::Update {
-                    position,
-                    goal_column: target_position.column(),
+                    position: point_for_position.previous_valid,
+                    goal_column: point_for_position.exact_unclipped.column(),
                     scroll_position: (position_map.snapshot.scroll_position() + scroll_delta)
                         .clamp(Vector2F::zero(), position_map.scroll_max),
                 },
@@ -452,10 +460,34 @@ impl EditorElement {
     ) -> bool {
         // This will be handled more correctly once https://github.com/zed-industries/zed/issues/1218 is completed
         // Don't trigger hover popover if mouse is hovering over context menu
-        let point = position_to_display_point(position, text_bounds, position_map);
-
-        update_go_to_definition_link(editor, point, cmd, shift, cx);
-        hover_at(editor, point, cx);
+        if text_bounds.contains_point(position) {
+            let point_for_position = position_map.point_for_position(text_bounds, position);
+            match point_for_position.as_valid() {
+                Some(point) => {
+                    update_go_to_definition_link(
+                        editor,
+                        Some(GoToDefinitionTrigger::Text(point)),
+                        cmd,
+                        shift,
+                        cx,
+                    );
+                    hover_at(editor, Some(point), cx);
+                }
+                None => {
+                    update_inlay_link_and_hover_points(
+                        &position_map.snapshot,
+                        point_for_position,
+                        editor,
+                        cmd,
+                        shift,
+                        cx,
+                    );
+                }
+            }
+        } else {
+            update_go_to_definition_link(editor, None, cmd, shift, cx);
+            hover_at(editor, None, cx);
+        }
 
         true
     }
@@ -763,7 +795,6 @@ impl EditorElement {
         cx: &mut PaintContext<Editor>,
     ) {
         let style = &self.style;
-        let local_replica_id = editor.replica_id(cx);
         let scroll_position = layout.position_map.snapshot.scroll_position();
         let start_row = layout.visible_display_row_range.start;
         let scroll_top = scroll_position.y() * layout.position_map.line_height;
@@ -852,15 +883,13 @@ impl EditorElement {
 
         for (replica_id, selections) in &layout.selections {
             let replica_id = *replica_id;
-            let selection_style = style.replica_selection_style(replica_id);
+            let selection_style = if let Some(replica_id) = replica_id {
+                style.replica_selection_style(replica_id)
+            } else {
+                &style.absent_selection
+            };
 
             for selection in selections {
-                if !selection.range.is_empty()
-                    && (replica_id == local_replica_id
-                        || Some(replica_id) == editor.leader_replica_id)
-                {
-                    invisible_display_ranges.push(selection.range.clone());
-                }
                 self.paint_highlighted_range(
                     scene,
                     selection.range.clone(),
@@ -874,7 +903,10 @@ impl EditorElement {
                     bounds,
                 );
 
-                if editor.show_local_cursors(cx) || replica_id != local_replica_id {
+                if selection.is_local && !selection.range.is_empty() {
+                    invisible_display_ranges.push(selection.range.clone());
+                }
+                if !selection.is_local || editor.show_local_cursors(cx) {
                     let cursor_position = selection.head;
                     if layout
                         .visible_display_row_range
@@ -906,7 +938,7 @@ impl EditorElement {
                                         &text,
                                         cursor_row_layout.font_size(),
                                         &[(
-                                            text.len(),
+                                            text.chars().count(),
                                             RunStyle {
                                                 font_id,
                                                 color: style.background,
@@ -1405,10 +1437,61 @@ impl EditorElement {
             .collect()
     }
 
+    fn calculate_relative_line_numbers(
+        &self,
+        snapshot: &EditorSnapshot,
+        rows: &Range<u32>,
+        relative_to: Option<u32>,
+    ) -> HashMap<u32, u32> {
+        let mut relative_rows: HashMap<u32, u32> = Default::default();
+        let Some(relative_to) = relative_to else {
+            return relative_rows;
+        };
+
+        let start = rows.start.min(relative_to);
+        let end = rows.end.max(relative_to);
+
+        let buffer_rows = snapshot
+            .buffer_rows(start)
+            .take(1 + (end - start) as usize)
+            .collect::<Vec<_>>();
+
+        let head_idx = relative_to - start;
+        let mut delta = 1;
+        let mut i = head_idx + 1;
+        while i < buffer_rows.len() as u32 {
+            if buffer_rows[i as usize].is_some() {
+                if rows.contains(&(i + start)) {
+                    relative_rows.insert(i + start, delta);
+                }
+                delta += 1;
+            }
+            i += 1;
+        }
+        delta = 1;
+        i = head_idx.min(buffer_rows.len() as u32 - 1);
+        while i > 0 && buffer_rows[i as usize].is_none() {
+            i -= 1;
+        }
+
+        while i > 0 {
+            i -= 1;
+            if buffer_rows[i as usize].is_some() {
+                if rows.contains(&(i + start)) {
+                    relative_rows.insert(i + start, delta);
+                }
+                delta += 1;
+            }
+        }
+
+        relative_rows
+    }
+
     fn layout_line_numbers(
         &self,
         rows: Range<u32>,
         active_rows: &BTreeMap<u32, bool>,
+        newest_selection_head: DisplayPoint,
         is_singleton: bool,
         snapshot: &EditorSnapshot,
         cx: &ViewContext<Editor>,
@@ -1421,6 +1504,15 @@ impl EditorElement {
         let mut line_number_layouts = Vec::with_capacity(rows.len());
         let mut fold_statuses = Vec::with_capacity(rows.len());
         let mut line_number = String::new();
+        let is_relative = settings::get::<EditorSettings>(cx).relative_line_numbers;
+        let relative_to = if is_relative {
+            Some(newest_selection_head.row())
+        } else {
+            None
+        };
+
+        let relative_rows = self.calculate_relative_line_numbers(&snapshot, &rows, relative_to);
+
         for (ix, row) in snapshot
             .buffer_rows(rows.start)
             .take((rows.end - rows.start) as usize)
@@ -1435,7 +1527,11 @@ impl EditorElement {
             if let Some(buffer_row) = row {
                 if include_line_numbers {
                     line_number.clear();
-                    write!(&mut line_number, "{}", buffer_row + 1).unwrap();
+                    let default_number = buffer_row + 1;
+                    let number = relative_rows
+                        .get(&(ix as u32 + rows.start))
+                        .unwrap_or(&default_number);
+                    write!(&mut line_number, "{}", number).unwrap();
                     line_number_layouts.push(Some(cx.text_layout_cache().layout_str(
                         &line_number,
                         style.text.font_size,
@@ -2079,14 +2175,11 @@ impl Element<Editor> for EditorElement {
                 scroll_height
                     .min(constraint.max_along(Axis::Vertical))
                     .max(constraint.min_along(Axis::Vertical))
+                    .max(line_height)
                     .min(line_height * max_lines as f32),
             )
         } else if let EditorMode::SingleLine = snapshot.mode {
-            size.set_y(
-                line_height
-                    .min(constraint.max_along(Axis::Vertical))
-                    .max(constraint.min_along(Axis::Vertical)),
-            )
+            size.set_y(line_height.max(constraint.min_along(Axis::Vertical)))
         } else if size.y().is_infinite() {
             size.set_y(scroll_height);
         }
@@ -2124,7 +2217,7 @@ impl Element<Editor> for EditorElement {
                 .anchor_before(DisplayPoint::new(end_row, 0).to_offset(&snapshot, Bias::Right))
         };
 
-        let mut selections: Vec<(ReplicaId, Vec<SelectionLayout>)> = Vec::new();
+        let mut selections: Vec<(Option<ReplicaId>, Vec<SelectionLayout>)> = Vec::new();
         let mut active_rows = BTreeMap::new();
         let mut fold_ranges = Vec::new();
         let is_singleton = editor.is_singleton(cx);
@@ -2155,8 +2248,14 @@ impl Element<Editor> for EditorElement {
             .buffer_snapshot
             .remote_selections_in_range(&(start_anchor..end_anchor))
         {
+            let replica_id = if let Some(mapping) = &editor.replica_id_mapping {
+                mapping.get(&replica_id).copied()
+            } else {
+                None
+            };
+
             // The local selections match the leader's selections.
-            if Some(replica_id) == editor.leader_replica_id {
+            if replica_id.is_some() && replica_id == editor.leader_replica_id {
                 continue;
             }
             remote_selections
@@ -2168,6 +2267,7 @@ impl Element<Editor> for EditorElement {
                     cursor_shape,
                     &snapshot.display_snapshot,
                     false,
+                    false,
                 ));
         }
         selections.extend(remote_selections);
@@ -2191,6 +2291,7 @@ impl Element<Editor> for EditorElement {
                     editor.cursor_shape,
                     &snapshot.display_snapshot,
                     is_newest,
+                    true,
                 );
                 if is_newest {
                     newest_selection_head = Some(layout.head);
@@ -2206,11 +2307,18 @@ impl Element<Editor> for EditorElement {
             }
 
             // Render the local selections in the leader's color when following.
-            let local_replica_id = editor
-                .leader_replica_id
-                .unwrap_or_else(|| editor.replica_id(cx));
+            let local_replica_id = if let Some(leader_replica_id) = editor.leader_replica_id {
+                leader_replica_id
+            } else {
+                let replica_id = editor.replica_id(cx);
+                if let Some(mapping) = &editor.replica_id_mapping {
+                    mapping.get(&replica_id).copied().unwrap_or(replica_id)
+                } else {
+                    replica_id
+                }
+            };
 
-            selections.push((local_replica_id, layouts));
+            selections.push((Some(local_replica_id), layouts));
         }
 
         let scrollbar_settings = &settings::get::<EditorSettings>(cx).scrollbar;
@@ -2244,9 +2352,23 @@ impl Element<Editor> for EditorElement {
             })
             .collect();
 
+        let head_for_relative = newest_selection_head.unwrap_or_else(|| {
+            let newest = editor.selections.newest::<Point>(cx);
+            SelectionLayout::new(
+                newest,
+                editor.selections.line_mode,
+                editor.cursor_shape,
+                &snapshot.display_snapshot,
+                true,
+                true,
+            )
+            .head
+        });
+
         let (line_number_layouts, fold_statuses) = self.layout_line_numbers(
             start_row..end_row,
             &active_rows,
+            head_for_relative,
             is_singleton,
             &snapshot,
             cx,
@@ -2591,7 +2713,7 @@ pub struct LayoutState {
     blocks: Vec<BlockLayout>,
     highlighted_ranges: Vec<(Range<DisplayPoint>, Color)>,
     fold_ranges: Vec<(BufferRow, Range<DisplayPoint>, Color)>,
-    selections: Vec<(ReplicaId, Vec<SelectionLayout>)>,
+    selections: Vec<(Option<ReplicaId>, Vec<SelectionLayout>)>,
     scrollbar_row_range: Range<f32>,
     show_scrollbars: bool,
     is_singleton: bool,
@@ -2614,22 +2736,42 @@ struct PositionMap {
     snapshot: EditorSnapshot,
 }
 
+#[derive(Debug, Copy, Clone)]
+pub struct PointForPosition {
+    pub previous_valid: DisplayPoint,
+    pub next_valid: DisplayPoint,
+    pub exact_unclipped: DisplayPoint,
+    pub column_overshoot_after_line_end: u32,
+}
+
+impl PointForPosition {
+    #[cfg(test)]
+    pub fn valid(valid: DisplayPoint) -> Self {
+        Self {
+            previous_valid: valid,
+            next_valid: valid,
+            exact_unclipped: valid,
+            column_overshoot_after_line_end: 0,
+        }
+    }
+
+    pub fn as_valid(&self) -> Option<DisplayPoint> {
+        if self.previous_valid == self.exact_unclipped && self.next_valid == self.exact_unclipped {
+            Some(self.previous_valid)
+        } else {
+            None
+        }
+    }
+}
+
 impl PositionMap {
-    /// Returns two display points:
-    /// 1. The nearest *valid* position in the editor
-    /// 2. An unclipped, potentially *invalid* position that maps directly to
-    ///    the given pixel position.
-    fn point_for_position(
-        &self,
-        text_bounds: RectF,
-        position: Vector2F,
-    ) -> (DisplayPoint, DisplayPoint) {
+    fn point_for_position(&self, text_bounds: RectF, position: Vector2F) -> PointForPosition {
         let scroll_position = self.snapshot.scroll_position();
         let position = position - text_bounds.origin();
         let y = position.y().max(0.0).min(self.size.y());
         let x = position.x() + (scroll_position.x() * self.em_width);
         let row = (y / self.line_height + scroll_position.y()) as u32;
-        let (column, x_overshoot) = if let Some(line) = self
+        let (column, x_overshoot_after_line_end) = if let Some(line) = self
             .line_layouts
             .get(row as usize - scroll_position.y() as usize)
             .map(|line_with_spaces| &line_with_spaces.line)
@@ -2643,11 +2785,18 @@ impl PositionMap {
             (0, x)
         };
 
-        let mut target_point = DisplayPoint::new(row, column);
-        let point = self.snapshot.clip_point(target_point, Bias::Left);
-        *target_point.column_mut() += (x_overshoot / self.em_advance) as u32;
+        let mut exact_unclipped = DisplayPoint::new(row, column);
+        let previous_valid = self.snapshot.clip_point(exact_unclipped, Bias::Left);
+        let next_valid = self.snapshot.clip_point(exact_unclipped, Bias::Right);
 
-        (point, target_point)
+        let column_overshoot_after_line_end = (x_overshoot_after_line_end / self.em_advance) as u32;
+        *exact_unclipped.column_mut() += column_overshoot_after_line_end;
+        PointForPosition {
+            previous_valid,
+            next_valid,
+            exact_unclipped,
+            column_overshoot_after_line_end,
+        }
     }
 }
 
@@ -2901,23 +3050,6 @@ impl HighlightedRange {
     }
 }
 
-fn position_to_display_point(
-    position: Vector2F,
-    text_bounds: RectF,
-    position_map: &PositionMap,
-) -> Option<DisplayPoint> {
-    if text_bounds.contains_point(position) {
-        let (point, target_point) = position_map.point_for_position(text_bounds, position);
-        if point == target_point {
-            Some(point)
-        } else {
-            None
-        }
-    } else {
-        None
-    }
-}
-
 fn range_to_bounds(
     range: &Range<DisplayPoint>,
     content_origin: Vector2F,
@@ -2995,7 +3127,6 @@ mod tests {
     #[gpui::test]
     fn test_layout_line_numbers(cx: &mut TestAppContext) {
         init_test(cx, |_| {});
-
         let editor = cx
             .add_window(|cx| {
                 let buffer = MultiBuffer::build_simple(&sample_text(6, 6, 'a'), cx);
@@ -3007,10 +3138,50 @@ mod tests {
         let layouts = editor.update(cx, |editor, cx| {
             let snapshot = editor.snapshot(cx);
             element
-                .layout_line_numbers(0..6, &Default::default(), false, &snapshot, cx)
+                .layout_line_numbers(
+                    0..6,
+                    &Default::default(),
+                    DisplayPoint::new(0, 0),
+                    false,
+                    &snapshot,
+                    cx,
+                )
                 .0
         });
         assert_eq!(layouts.len(), 6);
+
+        let relative_rows = editor.update(cx, |editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            element.calculate_relative_line_numbers(&snapshot, &(0..6), Some(3))
+        });
+        assert_eq!(relative_rows[&0], 3);
+        assert_eq!(relative_rows[&1], 2);
+        assert_eq!(relative_rows[&2], 1);
+        // current line has no relative number
+        assert_eq!(relative_rows[&4], 1);
+        assert_eq!(relative_rows[&5], 2);
+
+        // works if cursor is before screen
+        let relative_rows = editor.update(cx, |editor, cx| {
+            let snapshot = editor.snapshot(cx);
+
+            element.calculate_relative_line_numbers(&snapshot, &(3..6), Some(1))
+        });
+        assert_eq!(relative_rows.len(), 3);
+        assert_eq!(relative_rows[&3], 2);
+        assert_eq!(relative_rows[&4], 3);
+        assert_eq!(relative_rows[&5], 4);
+
+        // works if cursor is after screen
+        let relative_rows = editor.update(cx, |editor, cx| {
+            let snapshot = editor.snapshot(cx);
+
+            element.calculate_relative_line_numbers(&snapshot, &(0..3), Some(6))
+        });
+        assert_eq!(relative_rows.len(), 3);
+        assert_eq!(relative_rows[&0], 5);
+        assert_eq!(relative_rows[&1], 4);
+        assert_eq!(relative_rows[&2], 3);
     }
 
     #[gpui::test]

crates/editor/src/hover_popover.rs

@@ -1,6 +1,8 @@
 use crate::{
-    display_map::ToDisplayPoint, Anchor, AnchorRangeExt, DisplayPoint, Editor, EditorSettings,
-    EditorSnapshot, EditorStyle, RangeToAnchorExt,
+    display_map::{InlayOffset, ToDisplayPoint},
+    link_go_to_definition::{DocumentRange, InlayRange},
+    Anchor, AnchorRangeExt, DisplayPoint, Editor, EditorSettings, EditorSnapshot, EditorStyle,
+    ExcerptId, RangeToAnchorExt,
 };
 use futures::FutureExt;
 use gpui::{
@@ -11,7 +13,7 @@ use gpui::{
     AnyElement, AppContext, CursorRegion, Element, ModelHandle, MouseRegion, Task, ViewContext,
 };
 use language::{Bias, DiagnosticEntry, DiagnosticSeverity, Language, LanguageRegistry};
-use project::{HoverBlock, HoverBlockKind, Project};
+use project::{HoverBlock, HoverBlockKind, InlayHintLabelPart, Project};
 use std::{ops::Range, sync::Arc, time::Duration};
 use util::TryFutureExt;
 
@@ -46,6 +48,106 @@ pub fn hover_at(editor: &mut Editor, point: Option<DisplayPoint>, cx: &mut ViewC
     }
 }
 
+pub struct InlayHover {
+    pub excerpt: ExcerptId,
+    pub triggered_from: InlayOffset,
+    pub range: InlayRange,
+    pub tooltip: HoverBlock,
+}
+
+pub fn find_hovered_hint_part(
+    label_parts: Vec<InlayHintLabelPart>,
+    hint_range: Range<InlayOffset>,
+    hovered_offset: InlayOffset,
+) -> Option<(InlayHintLabelPart, Range<InlayOffset>)> {
+    if hovered_offset >= hint_range.start && hovered_offset <= hint_range.end {
+        let mut hovered_character = (hovered_offset - hint_range.start).0;
+        let mut part_start = hint_range.start;
+        for part in label_parts {
+            let part_len = part.value.chars().count();
+            if hovered_character > part_len {
+                hovered_character -= part_len;
+                part_start.0 += part_len;
+            } else {
+                let part_end = InlayOffset(part_start.0 + part_len);
+                return Some((part, part_start..part_end));
+            }
+        }
+    }
+    None
+}
+
+pub fn hover_at_inlay(editor: &mut Editor, inlay_hover: InlayHover, cx: &mut ViewContext<Editor>) {
+    if settings::get::<EditorSettings>(cx).hover_popover_enabled {
+        if editor.pending_rename.is_some() {
+            return;
+        }
+
+        let Some(project) = editor.project.clone() else {
+            return;
+        };
+
+        if let Some(InfoPopover { symbol_range, .. }) = &editor.hover_state.info_popover {
+            if let DocumentRange::Inlay(range) = symbol_range {
+                if (range.highlight_start..range.highlight_end)
+                    .contains(&inlay_hover.triggered_from)
+                {
+                    // Hover triggered from same location as last time. Don't show again.
+                    return;
+                }
+            }
+            hide_hover(editor, cx);
+        }
+
+        let snapshot = editor.snapshot(cx);
+        // Don't request again if the location is the same as the previous request
+        if let Some(triggered_from) = editor.hover_state.triggered_from {
+            if inlay_hover.triggered_from
+                == snapshot
+                    .display_snapshot
+                    .anchor_to_inlay_offset(triggered_from)
+            {
+                return;
+            }
+        }
+
+        let task = cx.spawn(|this, mut cx| {
+            async move {
+                cx.background()
+                    .timer(Duration::from_millis(HOVER_DELAY_MILLIS))
+                    .await;
+                this.update(&mut cx, |this, _| {
+                    this.hover_state.diagnostic_popover = None;
+                })?;
+
+                let hover_popover = InfoPopover {
+                    project: project.clone(),
+                    symbol_range: DocumentRange::Inlay(inlay_hover.range),
+                    blocks: vec![inlay_hover.tooltip],
+                    language: None,
+                    rendered_content: None,
+                };
+
+                this.update(&mut cx, |this, cx| {
+                    // Highlight the selected symbol using a background highlight
+                    this.highlight_inlay_background::<HoverState>(
+                        vec![inlay_hover.range],
+                        |theme| theme.editor.hover_popover.highlight,
+                        cx,
+                    );
+                    this.hover_state.info_popover = Some(hover_popover);
+                    cx.notify();
+                })?;
+
+                anyhow::Ok(())
+            }
+            .log_err()
+        });
+
+        editor.hover_state.info_task = Some(task);
+    }
+}
+
 /// Hides the type information popup.
 /// Triggered by the `Hover` action when the cursor is not over a symbol or when the
 /// selections changed.
@@ -110,8 +212,13 @@ fn show_hover(
     if !ignore_timeout {
         if let Some(InfoPopover { symbol_range, .. }) = &editor.hover_state.info_popover {
             if symbol_range
+                .as_text_range()
+                .map(|range| {
+                    range
                         .to_offset(&snapshot.buffer_snapshot)
                         .contains(&multibuffer_offset)
+                })
+                .unwrap_or(false)
             {
                 // Hover triggered from same location as last time. Don't show again.
                 return;
@@ -219,7 +326,7 @@ fn show_hover(
 
                 Some(InfoPopover {
                     project: project.clone(),
-                    symbol_range: range,
+                    symbol_range: DocumentRange::Text(range),
                     blocks: hover_result.contents,
                     language: hover_result.language,
                     rendered_content: None,
@@ -227,10 +334,13 @@ fn show_hover(
             });
 
             this.update(&mut cx, |this, cx| {
-                if let Some(hover_popover) = hover_popover.as_ref() {
+                if let Some(symbol_range) = hover_popover
+                    .as_ref()
+                    .and_then(|hover_popover| hover_popover.symbol_range.as_text_range())
+                {
                     // Highlight the selected symbol using a background highlight
                     this.highlight_background::<HoverState>(
-                        vec![hover_popover.symbol_range.clone()],
+                        vec![symbol_range],
                         |theme| theme.editor.hover_popover.highlight,
                         cx,
                     );
@@ -497,7 +607,10 @@ impl HoverState {
             .or_else(|| {
                 self.info_popover
                     .as_ref()
-                    .map(|info_popover| &info_popover.symbol_range.start)
+                    .map(|info_popover| match &info_popover.symbol_range {
+                        DocumentRange::Text(range) => &range.start,
+                        DocumentRange::Inlay(range) => &range.inlay_position,
+                    })
             })?;
         let point = anchor.to_display_point(&snapshot.display_snapshot);
 
@@ -522,7 +635,7 @@ impl HoverState {
 #[derive(Debug, Clone)]
 pub struct InfoPopover {
     pub project: ModelHandle<Project>,
-    pub symbol_range: Range<Anchor>,
+    symbol_range: DocumentRange,
     pub blocks: Vec<HoverBlock>,
     language: Option<Arc<Language>>,
     rendered_content: Option<RenderedInfo>,
@@ -692,10 +805,17 @@ impl DiagnosticPopover {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{editor_tests::init_test, test::editor_lsp_test_context::EditorLspTestContext};
+    use crate::{
+        editor_tests::init_test,
+        element::PointForPosition,
+        inlay_hint_cache::tests::{cached_hint_labels, visible_hint_labels},
+        link_go_to_definition::update_inlay_link_and_hover_points,
+        test::editor_lsp_test_context::EditorLspTestContext,
+    };
+    use collections::BTreeSet;
     use gpui::fonts::Weight;
     use indoc::indoc;
-    use language::{Diagnostic, DiagnosticSet};
+    use language::{language_settings::InlayHintSettings, Diagnostic, DiagnosticSet};
     use lsp::LanguageServerId;
     use project::{HoverBlock, HoverBlockKind};
     use smol::stream::StreamExt;
@@ -1131,4 +1251,327 @@ mod tests {
             editor
         });
     }
+
+    #[gpui::test]
+    async fn test_hover_inlay_label_parts(cx: &mut gpui::TestAppContext) {
+        init_test(cx, |settings| {
+            settings.defaults.inlay_hints = Some(InlayHintSettings {
+                enabled: true,
+                show_type_hints: true,
+                show_parameter_hints: true,
+                show_other_hints: true,
+            })
+        });
+
+        let mut cx = EditorLspTestContext::new_rust(
+            lsp::ServerCapabilities {
+                inlay_hint_provider: Some(lsp::OneOf::Right(
+                    lsp::InlayHintServerCapabilities::Options(lsp::InlayHintOptions {
+                        resolve_provider: Some(true),
+                        ..Default::default()
+                    }),
+                )),
+                ..Default::default()
+            },
+            cx,
+        )
+        .await;
+
+        cx.set_state(indoc! {"
+            struct TestStruct;
+
+            // ==================
+
+            struct TestNewType<T>(T);
+
+            fn main() {
+                let variableˇ = TestNewType(TestStruct);
+            }
+        "});
+
+        let hint_start_offset = cx.ranges(indoc! {"
+            struct TestStruct;
+
+            // ==================
+
+            struct TestNewType<T>(T);
+
+            fn main() {
+                let variableˇ = TestNewType(TestStruct);
+            }
+        "})[0]
+            .start;
+        let hint_position = cx.to_lsp(hint_start_offset);
+        let new_type_target_range = cx.lsp_range(indoc! {"
+            struct TestStruct;
+
+            // ==================
+
+            struct «TestNewType»<T>(T);
+
+            fn main() {
+                let variable = TestNewType(TestStruct);
+            }
+        "});
+        let struct_target_range = cx.lsp_range(indoc! {"
+            struct «TestStruct»;
+
+            // ==================
+
+            struct TestNewType<T>(T);
+
+            fn main() {
+                let variable = TestNewType(TestStruct);
+            }
+        "});
+
+        let uri = cx.buffer_lsp_url.clone();
+        let new_type_label = "TestNewType";
+        let struct_label = "TestStruct";
+        let entire_hint_label = ": TestNewType<TestStruct>";
+        let closure_uri = uri.clone();
+        cx.lsp
+            .handle_request::<lsp::request::InlayHintRequest, _, _>(move |params, _| {
+                let task_uri = closure_uri.clone();
+                async move {
+                    assert_eq!(params.text_document.uri, task_uri);
+                    Ok(Some(vec![lsp::InlayHint {
+                        position: hint_position,
+                        label: lsp::InlayHintLabel::LabelParts(vec![lsp::InlayHintLabelPart {
+                            value: entire_hint_label.to_string(),
+                            ..Default::default()
+                        }]),
+                        kind: Some(lsp::InlayHintKind::TYPE),
+                        text_edits: None,
+                        tooltip: None,
+                        padding_left: Some(false),
+                        padding_right: Some(false),
+                        data: None,
+                    }]))
+                }
+            })
+            .next()
+            .await;
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            let expected_layers = vec![entire_hint_label.to_string()];
+            assert_eq!(expected_layers, cached_hint_labels(editor));
+            assert_eq!(expected_layers, visible_hint_labels(editor, cx));
+        });
+
+        let inlay_range = cx
+            .ranges(indoc! {"
+                struct TestStruct;
+
+                // ==================
+
+                struct TestNewType<T>(T);
+
+                fn main() {
+                    let variable« »= TestNewType(TestStruct);
+                }
+        "})
+            .get(0)
+            .cloned()
+            .unwrap();
+        let new_type_hint_part_hover_position = cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let previous_valid = inlay_range.start.to_display_point(&snapshot);
+            let next_valid = inlay_range.end.to_display_point(&snapshot);
+            assert_eq!(previous_valid.row(), next_valid.row());
+            assert!(previous_valid.column() < next_valid.column());
+            let exact_unclipped = DisplayPoint::new(
+                previous_valid.row(),
+                previous_valid.column()
+                    + (entire_hint_label.find(new_type_label).unwrap() + new_type_label.len() / 2)
+                        as u32,
+            );
+            PointForPosition {
+                previous_valid,
+                next_valid,
+                exact_unclipped,
+                column_overshoot_after_line_end: 0,
+            }
+        });
+        cx.update_editor(|editor, cx| {
+            update_inlay_link_and_hover_points(
+                &editor.snapshot(cx),
+                new_type_hint_part_hover_position,
+                editor,
+                true,
+                false,
+                cx,
+            );
+        });
+
+        let resolve_closure_uri = uri.clone();
+        cx.lsp
+            .handle_request::<lsp::request::InlayHintResolveRequest, _, _>(
+                move |mut hint_to_resolve, _| {
+                    let mut resolved_hint_positions = BTreeSet::new();
+                    let task_uri = resolve_closure_uri.clone();
+                    async move {
+                        let inserted = resolved_hint_positions.insert(hint_to_resolve.position);
+                        assert!(inserted, "Hint {hint_to_resolve:?} was resolved twice");
+
+                        // `: TestNewType<TestStruct>`
+                        hint_to_resolve.label = lsp::InlayHintLabel::LabelParts(vec![
+                            lsp::InlayHintLabelPart {
+                                value: ": ".to_string(),
+                                ..Default::default()
+                            },
+                            lsp::InlayHintLabelPart {
+                                value: new_type_label.to_string(),
+                                location: Some(lsp::Location {
+                                    uri: task_uri.clone(),
+                                    range: new_type_target_range,
+                                }),
+                                tooltip: Some(lsp::InlayHintLabelPartTooltip::String(format!(
+                                    "A tooltip for `{new_type_label}`"
+                                ))),
+                                ..Default::default()
+                            },
+                            lsp::InlayHintLabelPart {
+                                value: "<".to_string(),
+                                ..Default::default()
+                            },
+                            lsp::InlayHintLabelPart {
+                                value: struct_label.to_string(),
+                                location: Some(lsp::Location {
+                                    uri: task_uri,
+                                    range: struct_target_range,
+                                }),
+                                tooltip: Some(lsp::InlayHintLabelPartTooltip::MarkupContent(
+                                    lsp::MarkupContent {
+                                        kind: lsp::MarkupKind::Markdown,
+                                        value: format!("A tooltip for `{struct_label}`"),
+                                    },
+                                )),
+                                ..Default::default()
+                            },
+                            lsp::InlayHintLabelPart {
+                                value: ">".to_string(),
+                                ..Default::default()
+                            },
+                        ]);
+
+                        Ok(hint_to_resolve)
+                    }
+                },
+            )
+            .next()
+            .await;
+        cx.foreground().run_until_parked();
+
+        cx.update_editor(|editor, cx| {
+            update_inlay_link_and_hover_points(
+                &editor.snapshot(cx),
+                new_type_hint_part_hover_position,
+                editor,
+                true,
+                false,
+                cx,
+            );
+        });
+        cx.foreground()
+            .advance_clock(Duration::from_millis(HOVER_DELAY_MILLIS + 100));
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let hover_state = &editor.hover_state;
+            assert!(hover_state.diagnostic_popover.is_none() && hover_state.info_popover.is_some());
+            let popover = hover_state.info_popover.as_ref().unwrap();
+            let buffer_snapshot = editor.buffer().update(cx, |buffer, cx| buffer.snapshot(cx));
+            let entire_inlay_start = snapshot.display_point_to_inlay_offset(
+                inlay_range.start.to_display_point(&snapshot),
+                Bias::Left,
+            );
+
+            let expected_new_type_label_start = InlayOffset(entire_inlay_start.0 + ": ".len());
+            assert_eq!(
+                popover.symbol_range,
+                DocumentRange::Inlay(InlayRange {
+                    inlay_position: buffer_snapshot.anchor_at(inlay_range.start, Bias::Right),
+                    highlight_start: expected_new_type_label_start,
+                    highlight_end: InlayOffset(
+                        expected_new_type_label_start.0 + new_type_label.len()
+                    ),
+                }),
+                "Popover range should match the new type label part"
+            );
+            assert_eq!(
+                popover
+                    .rendered_content
+                    .as_ref()
+                    .expect("should have label text for new type hint")
+                    .text,
+                format!("A tooltip for `{new_type_label}`"),
+                "Rendered text should not anyhow alter backticks"
+            );
+        });
+
+        let struct_hint_part_hover_position = cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let previous_valid = inlay_range.start.to_display_point(&snapshot);
+            let next_valid = inlay_range.end.to_display_point(&snapshot);
+            assert_eq!(previous_valid.row(), next_valid.row());
+            assert!(previous_valid.column() < next_valid.column());
+            let exact_unclipped = DisplayPoint::new(
+                previous_valid.row(),
+                previous_valid.column()
+                    + (entire_hint_label.find(struct_label).unwrap() + struct_label.len() / 2)
+                        as u32,
+            );
+            PointForPosition {
+                previous_valid,
+                next_valid,
+                exact_unclipped,
+                column_overshoot_after_line_end: 0,
+            }
+        });
+        cx.update_editor(|editor, cx| {
+            update_inlay_link_and_hover_points(
+                &editor.snapshot(cx),
+                struct_hint_part_hover_position,
+                editor,
+                true,
+                false,
+                cx,
+            );
+        });
+        cx.foreground()
+            .advance_clock(Duration::from_millis(HOVER_DELAY_MILLIS + 100));
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let hover_state = &editor.hover_state;
+            assert!(hover_state.diagnostic_popover.is_none() && hover_state.info_popover.is_some());
+            let popover = hover_state.info_popover.as_ref().unwrap();
+            let buffer_snapshot = editor.buffer().update(cx, |buffer, cx| buffer.snapshot(cx));
+            let entire_inlay_start = snapshot.display_point_to_inlay_offset(
+                inlay_range.start.to_display_point(&snapshot),
+                Bias::Left,
+            );
+            let expected_struct_label_start =
+                InlayOffset(entire_inlay_start.0 + ": ".len() + new_type_label.len() + "<".len());
+            assert_eq!(
+                popover.symbol_range,
+                DocumentRange::Inlay(InlayRange {
+                    inlay_position: buffer_snapshot.anchor_at(inlay_range.start, Bias::Right),
+                    highlight_start: expected_struct_label_start,
+                    highlight_end: InlayOffset(expected_struct_label_start.0 + struct_label.len()),
+                }),
+                "Popover range should match the struct label part"
+            );
+            assert_eq!(
+                popover
+                    .rendered_content
+                    .as_ref()
+                    .expect("should have label text for struct hint")
+                    .text,
+                format!("A tooltip for {struct_label}"),
+                "Rendered markdown element should remove backticks from text"
+            );
+        });
+    }
 }

crates/editor/src/items.rs

@@ -49,13 +49,18 @@ impl FollowableItem for Editor {
 
     fn from_state_proto(
         pane: ViewHandle<workspace::Pane>,
-        project: ModelHandle<Project>,
+        workspace: ViewHandle<Workspace>,
         remote_id: ViewId,
         state: &mut Option<proto::view::Variant>,
         cx: &mut AppContext,
     ) -> Option<Task<Result<ViewHandle<Self>>>> {
-        let Some(proto::view::Variant::Editor(_)) = state else { return None };
-        let Some(proto::view::Variant::Editor(state)) = state.take() else { unreachable!() };
+        let project = workspace.read(cx).project().to_owned();
+        let Some(proto::view::Variant::Editor(_)) = state else {
+            return None;
+        };
+        let Some(proto::view::Variant::Editor(state)) = state.take() else {
+            unreachable!()
+        };
 
         let client = project.read(cx).client();
         let replica_id = project.read(cx).replica_id();
@@ -340,10 +345,16 @@ async fn update_editor_from_message(
 
             let mut insertions = message.inserted_excerpts.into_iter().peekable();
             while let Some(insertion) = insertions.next() {
-                let Some(excerpt) = insertion.excerpt else { continue };
-                let Some(previous_excerpt_id) = insertion.previous_excerpt_id else { continue };
+                let Some(excerpt) = insertion.excerpt else {
+                    continue;
+                };
+                let Some(previous_excerpt_id) = insertion.previous_excerpt_id else {
+                    continue;
+                };
                 let buffer_id = excerpt.buffer_id;
-                let Some(buffer) = project.read(cx).buffer_for_id(buffer_id, cx) else { continue };
+                let Some(buffer) = project.read(cx).buffer_for_id(buffer_id, cx) else {
+                    continue;
+                };
 
                 let adjacent_excerpts = iter::from_fn(|| {
                     let insertion = insertions.peek()?;
@@ -614,7 +625,7 @@ impl Item for Editor {
 
     fn workspace_deactivated(&mut self, cx: &mut ViewContext<Self>) {
         hide_link_definition(self, cx);
-        self.link_go_to_definition_state.last_mouse_location = None;
+        self.link_go_to_definition_state.last_trigger_point = None;
     }
 
     fn is_dirty(&self, cx: &AppContext) -> bool {
@@ -753,7 +764,7 @@ impl Item for Editor {
         Some(Box::new(handle.clone()))
     }
 
-    fn pixel_position_of_cursor(&self) -> Option<Vector2F> {
+    fn pixel_position_of_cursor(&self, _: &AppContext) -> Option<Vector2F> {
         self.pixel_position_of_newest_cursor
     }
 

crates/editor/src/link_go_to_definition.rs

@@ -1,22 +1,108 @@
-use crate::{Anchor, DisplayPoint, Editor, EditorSnapshot, SelectPhase};
+use crate::{
+    display_map::{DisplaySnapshot, InlayOffset},
+    element::PointForPosition,
+    hover_popover::{self, InlayHover},
+    Anchor, DisplayPoint, Editor, EditorSnapshot, SelectPhase,
+};
 use gpui::{Task, ViewContext};
 use language::{Bias, ToOffset};
-use project::LocationLink;
+use lsp::LanguageServerId;
+use project::{
+    HoverBlock, HoverBlockKind, InlayHintLabelPartTooltip, InlayHintTooltip, LocationLink,
+    ResolveState,
+};
 use std::ops::Range;
 use util::TryFutureExt;
 
 #[derive(Debug, Default)]
 pub struct LinkGoToDefinitionState {
-    pub last_mouse_location: Option<Anchor>,
-    pub symbol_range: Option<Range<Anchor>>,
+    pub last_trigger_point: Option<TriggerPoint>,
+    pub symbol_range: Option<DocumentRange>,
     pub kind: Option<LinkDefinitionKind>,
-    pub definitions: Vec<LocationLink>,
+    pub definitions: Vec<GoToDefinitionLink>,
     pub task: Option<Task<Option<()>>>,
 }
 
+#[derive(Debug)]
+pub enum GoToDefinitionTrigger {
+    Text(DisplayPoint),
+    InlayHint(InlayRange, lsp::Location, LanguageServerId),
+}
+
+#[derive(Debug, Clone)]
+pub enum GoToDefinitionLink {
+    Text(LocationLink),
+    InlayHint(lsp::Location, LanguageServerId),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct InlayRange {
+    pub inlay_position: Anchor,
+    pub highlight_start: InlayOffset,
+    pub highlight_end: InlayOffset,
+}
+
+#[derive(Debug, Clone)]
+pub enum TriggerPoint {
+    Text(Anchor),
+    InlayHint(InlayRange, lsp::Location, LanguageServerId),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum DocumentRange {
+    Text(Range<Anchor>),
+    Inlay(InlayRange),
+}
+
+impl DocumentRange {
+    pub fn as_text_range(&self) -> Option<Range<Anchor>> {
+        match self {
+            Self::Text(range) => Some(range.clone()),
+            Self::Inlay(_) => None,
+        }
+    }
+
+    fn point_within_range(&self, trigger_point: &TriggerPoint, snapshot: &EditorSnapshot) -> bool {
+        match (self, trigger_point) {
+            (DocumentRange::Text(range), TriggerPoint::Text(point)) => {
+                let point_after_start = range.start.cmp(point, &snapshot.buffer_snapshot).is_le();
+                point_after_start && range.end.cmp(point, &snapshot.buffer_snapshot).is_ge()
+            }
+            (DocumentRange::Inlay(range), TriggerPoint::InlayHint(point, _, _)) => {
+                range.highlight_start.cmp(&point.highlight_end).is_le()
+                    && range.highlight_end.cmp(&point.highlight_end).is_ge()
+            }
+            (DocumentRange::Inlay(_), TriggerPoint::Text(_))
+            | (DocumentRange::Text(_), TriggerPoint::InlayHint(_, _, _)) => false,
+        }
+    }
+}
+
+impl TriggerPoint {
+    fn anchor(&self) -> &Anchor {
+        match self {
+            TriggerPoint::Text(anchor) => anchor,
+            TriggerPoint::InlayHint(range, _, _) => &range.inlay_position,
+        }
+    }
+
+    pub fn definition_kind(&self, shift: bool) -> LinkDefinitionKind {
+        match self {
+            TriggerPoint::Text(_) => {
+                if shift {
+                    LinkDefinitionKind::Type
+                } else {
+                    LinkDefinitionKind::Symbol
+                }
+            }
+            TriggerPoint::InlayHint(_, _, _) => LinkDefinitionKind::Type,
+        }
+    }
+}
+
 pub fn update_go_to_definition_link(
     editor: &mut Editor,
-    point: Option<DisplayPoint>,
+    origin: Option<GoToDefinitionTrigger>,
     cmd_held: bool,
     shift_held: bool,
     cx: &mut ViewContext<Editor>,
@@ -25,23 +111,43 @@ pub fn update_go_to_definition_link(
 
     // Store new mouse point as an anchor
     let snapshot = editor.snapshot(cx);
-    let point = point.map(|point| {
-        snapshot
-            .buffer_snapshot
-            .anchor_before(point.to_offset(&snapshot.display_snapshot, Bias::Left))
-    });
+    let trigger_point = match origin {
+        Some(GoToDefinitionTrigger::Text(p)) => {
+            Some(TriggerPoint::Text(snapshot.buffer_snapshot.anchor_before(
+                p.to_offset(&snapshot.display_snapshot, Bias::Left),
+            )))
+        }
+        Some(GoToDefinitionTrigger::InlayHint(p, lsp_location, language_server_id)) => {
+            Some(TriggerPoint::InlayHint(p, lsp_location, language_server_id))
+        }
+        None => None,
+    };
 
     // If the new point is the same as the previously stored one, return early
     if let (Some(a), Some(b)) = (
-        &point,
-        &editor.link_go_to_definition_state.last_mouse_location,
+        &trigger_point,
+        &editor.link_go_to_definition_state.last_trigger_point,
     ) {
-        if a.cmp(b, &snapshot.buffer_snapshot).is_eq() {
+        match (a, b) {
+            (TriggerPoint::Text(anchor_a), TriggerPoint::Text(anchor_b)) => {
+                if anchor_a.cmp(anchor_b, &snapshot.buffer_snapshot).is_eq() {
                     return;
                 }
             }
+            (TriggerPoint::InlayHint(range_a, _, _), TriggerPoint::InlayHint(range_b, _, _)) => {
+                if range_a
+                    .inlay_position
+                    .cmp(&range_b.inlay_position, &snapshot.buffer_snapshot)
+                    .is_eq()
+                {
+                    return;
+                }
+            }
+            _ => {}
+        }
+    }
 
-    editor.link_go_to_definition_state.last_mouse_location = point.clone();
+    editor.link_go_to_definition_state.last_trigger_point = trigger_point.clone();
 
     if pending_nonempty_selection {
         hide_link_definition(editor, cx);
@@ -49,14 +155,9 @@ pub fn update_go_to_definition_link(
     }
 
     if cmd_held {
-        if let Some(point) = point {
-            let kind = if shift_held {
-                LinkDefinitionKind::Type
-            } else {
-                LinkDefinitionKind::Symbol
-            };
-
-            show_link_definition(kind, editor, point, snapshot, cx);
+        if let Some(trigger_point) = trigger_point {
+            let kind = trigger_point.definition_kind(shift_held);
+            show_link_definition(kind, editor, trigger_point, snapshot, cx);
             return;
         }
     }
@@ -64,6 +165,182 @@ pub fn update_go_to_definition_link(
     hide_link_definition(editor, cx);
 }
 
+pub fn update_inlay_link_and_hover_points(
+    snapshot: &DisplaySnapshot,
+    point_for_position: PointForPosition,
+    editor: &mut Editor,
+    cmd_held: bool,
+    shift_held: bool,
+    cx: &mut ViewContext<'_, '_, Editor>,
+) {
+    let hint_start_offset =
+        snapshot.display_point_to_inlay_offset(point_for_position.previous_valid, Bias::Left);
+    let hint_end_offset =
+        snapshot.display_point_to_inlay_offset(point_for_position.next_valid, Bias::Right);
+    let hovered_offset = if point_for_position.column_overshoot_after_line_end == 0 {
+        Some(snapshot.display_point_to_inlay_offset(point_for_position.exact_unclipped, Bias::Left))
+    } else {
+        None
+    };
+    let mut go_to_definition_updated = false;
+    let mut hover_updated = false;
+    if let Some(hovered_offset) = hovered_offset {
+        let buffer_snapshot = editor.buffer().read(cx).snapshot(cx);
+        let previous_valid_anchor = buffer_snapshot.anchor_at(
+            point_for_position.previous_valid.to_point(snapshot),
+            Bias::Left,
+        );
+        let next_valid_anchor = buffer_snapshot.anchor_at(
+            point_for_position.next_valid.to_point(snapshot),
+            Bias::Right,
+        );
+        if let Some(hovered_hint) = editor
+            .visible_inlay_hints(cx)
+            .into_iter()
+            .skip_while(|hint| {
+                hint.position
+                    .cmp(&previous_valid_anchor, &buffer_snapshot)
+                    .is_lt()
+            })
+            .take_while(|hint| {
+                hint.position
+                    .cmp(&next_valid_anchor, &buffer_snapshot)
+                    .is_le()
+            })
+            .max_by_key(|hint| hint.id)
+        {
+            let inlay_hint_cache = editor.inlay_hint_cache();
+            let excerpt_id = previous_valid_anchor.excerpt_id;
+            if let Some(cached_hint) = inlay_hint_cache.hint_by_id(excerpt_id, hovered_hint.id) {
+                match cached_hint.resolve_state {
+                    ResolveState::CanResolve(_, _) => {
+                        if let Some(buffer_id) = previous_valid_anchor.buffer_id {
+                            inlay_hint_cache.spawn_hint_resolve(
+                                buffer_id,
+                                excerpt_id,
+                                hovered_hint.id,
+                                cx,
+                            );
+                        }
+                    }
+                    ResolveState::Resolved => {
+                        let mut actual_hint_start = hint_start_offset;
+                        let mut actual_hint_end = hint_end_offset;
+                        if cached_hint.padding_left {
+                            actual_hint_start.0 += 1;
+                            actual_hint_end.0 += 1;
+                        }
+                        if cached_hint.padding_right {
+                            actual_hint_start.0 += 1;
+                            actual_hint_end.0 += 1;
+                        }
+                        match cached_hint.label {
+                            project::InlayHintLabel::String(_) => {
+                                if let Some(tooltip) = cached_hint.tooltip {
+                                    hover_popover::hover_at_inlay(
+                                        editor,
+                                        InlayHover {
+                                            excerpt: excerpt_id,
+                                            tooltip: match tooltip {
+                                                InlayHintTooltip::String(text) => HoverBlock {
+                                                    text,
+                                                    kind: HoverBlockKind::PlainText,
+                                                },
+                                                InlayHintTooltip::MarkupContent(content) => {
+                                                    HoverBlock {
+                                                        text: content.value,
+                                                        kind: content.kind,
+                                                    }
+                                                }
+                                            },
+                                            triggered_from: hovered_offset,
+                                            range: InlayRange {
+                                                inlay_position: hovered_hint.position,
+                                                highlight_start: actual_hint_start,
+                                                highlight_end: actual_hint_end,
+                                            },
+                                        },
+                                        cx,
+                                    );
+                                    hover_updated = true;
+                                }
+                            }
+                            project::InlayHintLabel::LabelParts(label_parts) => {
+                                if let Some((hovered_hint_part, part_range)) =
+                                    hover_popover::find_hovered_hint_part(
+                                        label_parts,
+                                        actual_hint_start..actual_hint_end,
+                                        hovered_offset,
+                                    )
+                                {
+                                    if let Some(tooltip) = hovered_hint_part.tooltip {
+                                        hover_popover::hover_at_inlay(
+                                            editor,
+                                            InlayHover {
+                                                excerpt: excerpt_id,
+                                                tooltip: match tooltip {
+                                                    InlayHintLabelPartTooltip::String(text) => {
+                                                        HoverBlock {
+                                                            text,
+                                                            kind: HoverBlockKind::PlainText,
+                                                        }
+                                                    }
+                                                    InlayHintLabelPartTooltip::MarkupContent(
+                                                        content,
+                                                    ) => HoverBlock {
+                                                        text: content.value,
+                                                        kind: content.kind,
+                                                    },
+                                                },
+                                                triggered_from: hovered_offset,
+                                                range: InlayRange {
+                                                    inlay_position: hovered_hint.position,
+                                                    highlight_start: part_range.start,
+                                                    highlight_end: part_range.end,
+                                                },
+                                            },
+                                            cx,
+                                        );
+                                        hover_updated = true;
+                                    }
+                                    if let Some((language_server_id, location)) =
+                                        hovered_hint_part.location
+                                    {
+                                        go_to_definition_updated = true;
+                                        update_go_to_definition_link(
+                                            editor,
+                                            Some(GoToDefinitionTrigger::InlayHint(
+                                                InlayRange {
+                                                    inlay_position: hovered_hint.position,
+                                                    highlight_start: part_range.start,
+                                                    highlight_end: part_range.end,
+                                                },
+                                                location,
+                                                language_server_id,
+                                            )),
+                                            cmd_held,
+                                            shift_held,
+                                            cx,
+                                        );
+                                    }
+                                }
+                            }
+                        };
+                    }
+                    ResolveState::Resolving => {}
+                }
+            }
+        }
+    }
+
+    if !go_to_definition_updated {
+        update_go_to_definition_link(editor, None, cmd_held, shift_held, cx);
+    }
+    if !hover_updated {
+        hover_popover::hover_at(editor, None, cx);
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum LinkDefinitionKind {
     Symbol,
@@ -73,7 +350,7 @@ pub enum LinkDefinitionKind {
 pub fn show_link_definition(
     definition_kind: LinkDefinitionKind,
     editor: &mut Editor,
-    trigger_point: Anchor,
+    trigger_point: TriggerPoint,
     snapshot: EditorSnapshot,
     cx: &mut ViewContext<Editor>,
 ) {
@@ -86,10 +363,11 @@ pub fn show_link_definition(
         return;
     }
 
+    let trigger_anchor = trigger_point.anchor();
     let (buffer, buffer_position) = if let Some(output) = editor
         .buffer
         .read(cx)
-        .text_anchor_for_position(trigger_point.clone(), cx)
+        .text_anchor_for_position(trigger_anchor.clone(), cx)
     {
         output
     } else {
@@ -99,7 +377,7 @@ pub fn show_link_definition(
     let excerpt_id = if let Some((excerpt_id, _, _)) = editor
         .buffer()
         .read(cx)
-        .excerpt_containing(trigger_point.clone(), cx)
+        .excerpt_containing(trigger_anchor.clone(), cx)
     {
         excerpt_id
     } else {
@@ -114,36 +392,30 @@ pub fn show_link_definition(
 
     // Don't request again if the location is within the symbol region of a previous request with the same kind
     if let Some(symbol_range) = &editor.link_go_to_definition_state.symbol_range {
-        let point_after_start = symbol_range
-            .start
-            .cmp(&trigger_point, &snapshot.buffer_snapshot)
-            .is_le();
-
-        let point_before_end = symbol_range
-            .end
-            .cmp(&trigger_point, &snapshot.buffer_snapshot)
-            .is_ge();
-
-        let point_within_range = point_after_start && point_before_end;
-        if point_within_range && same_kind {
+        if same_kind && symbol_range.point_within_range(&trigger_point, &snapshot) {
             return;
         }
     }
 
     let task = cx.spawn(|this, mut cx| {
         async move {
+            let result = match &trigger_point {
+                TriggerPoint::Text(_) => {
                     // query the LSP for definition info
-            let definition_request = cx.update(|cx| {
+                    cx.update(|cx| {
                         project.update(cx, |project, cx| match definition_kind {
-                    LinkDefinitionKind::Symbol => project.definition(&buffer, buffer_position, cx),
+                            LinkDefinitionKind::Symbol => {
+                                project.definition(&buffer, buffer_position, cx)
+                            }
 
                             LinkDefinitionKind::Type => {
                                 project.type_definition(&buffer, buffer_position, cx)
                             }
                         })
-            });
-
-            let result = definition_request.await.ok().map(|definition_result| {
+                    })
+                    .await
+                    .ok()
+                    .map(|definition_result| {
                         (
                             definition_result.iter().find_map(|link| {
                                 link.origin.as_ref().map(|origin| {
@@ -153,13 +425,24 @@ pub fn show_link_definition(
                                     let end = snapshot
                                         .buffer_snapshot
                                         .anchor_in_excerpt(excerpt_id.clone(), origin.range.end);
-
-                            start..end
+                                    DocumentRange::Text(start..end)
                                 })
                             }),
-                    definition_result,
+                            definition_result
+                                .into_iter()
+                                .map(GoToDefinitionLink::Text)
+                                .collect(),
                         )
-            });
+                    })
+                }
+                TriggerPoint::InlayHint(trigger_source, lsp_location, server_id) => Some((
+                    Some(DocumentRange::Inlay(*trigger_source)),
+                    vec![GoToDefinitionLink::InlayHint(
+                        lsp_location.clone(),
+                        *server_id,
+                    )],
+                )),
+            };
 
             this.update(&mut cx, |this, cx| {
                 // Clear any existing highlights
@@ -178,13 +461,17 @@ pub fn show_link_definition(
                     // the current location.
                     let any_definition_does_not_contain_current_location =
                         definitions.iter().any(|definition| {
-                            let target = &definition.target;
-                            if target.buffer == buffer {
-                                let range = &target.range;
+                            match &definition {
+                                GoToDefinitionLink::Text(link) => {
+                                    if link.target.buffer == buffer {
+                                        let range = &link.target.range;
                                         // Expand range by one character as lsp definition ranges include positions adjacent
                                         // but not contained by the symbol range
                                         let start = buffer_snapshot.clip_offset(
-                                    range.start.to_offset(&buffer_snapshot).saturating_sub(1),
+                                            range
+                                                .start
+                                                .to_offset(&buffer_snapshot)
+                                                .saturating_sub(1),
                                             Bias::Left,
                                         );
                                         let end = buffer_snapshot.clip_offset(
@@ -196,25 +483,45 @@ pub fn show_link_definition(
                                     } else {
                                         true
                                     }
+                                }
+                                GoToDefinitionLink::InlayHint(_, _) => true,
+                            }
                         });
 
                     if any_definition_does_not_contain_current_location {
-                        // If no symbol range returned from language server, use the surrounding word.
-                        let highlight_range = symbol_range.unwrap_or_else(|| {
-                            let snapshot = &snapshot.buffer_snapshot;
-                            let (offset_range, _) = snapshot.surrounding_word(trigger_point);
-
-                            snapshot.anchor_before(offset_range.start)
-                                ..snapshot.anchor_after(offset_range.end)
-                        });
-
                         // Highlight symbol using theme link definition highlight style
                         let style = theme::current(cx).editor.link_definition;
-                        this.highlight_text::<LinkGoToDefinitionState>(
-                            vec![highlight_range],
+                        let highlight_range =
+                            symbol_range.unwrap_or_else(|| match &trigger_point {
+                                TriggerPoint::Text(trigger_anchor) => {
+                                    let snapshot = &snapshot.buffer_snapshot;
+                                    // If no symbol range returned from language server, use the surrounding word.
+                                    let (offset_range, _) =
+                                        snapshot.surrounding_word(*trigger_anchor);
+                                    DocumentRange::Text(
+                                        snapshot.anchor_before(offset_range.start)
+                                            ..snapshot.anchor_after(offset_range.end),
+                                    )
+                                }
+                                TriggerPoint::InlayHint(inlay_coordinates, _, _) => {
+                                    DocumentRange::Inlay(*inlay_coordinates)
+                                }
+                            });
+
+                        match highlight_range {
+                            DocumentRange::Text(text_range) => this
+                                .highlight_text::<LinkGoToDefinitionState>(
+                                    vec![text_range],
                                     style,
                                     cx,
-                        );
+                                ),
+                            DocumentRange::Inlay(inlay_coordinates) => this
+                                .highlight_inlays::<LinkGoToDefinitionState>(
+                                    vec![inlay_coordinates],
+                                    style,
+                                    cx,
+                                ),
+                        }
                     } else {
                         hide_link_definition(this, cx);
                     }
@@ -245,7 +552,7 @@ pub fn hide_link_definition(editor: &mut Editor, cx: &mut ViewContext<Editor>) {
 
 pub fn go_to_fetched_definition(
     editor: &mut Editor,
-    point: DisplayPoint,
+    point: PointForPosition,
     split: bool,
     cx: &mut ViewContext<Editor>,
 ) {
@@ -254,7 +561,7 @@ pub fn go_to_fetched_definition(
 
 pub fn go_to_fetched_type_definition(
     editor: &mut Editor,
-    point: DisplayPoint,
+    point: PointForPosition,
     split: bool,
     cx: &mut ViewContext<Editor>,
 ) {
@@ -264,7 +571,7 @@ pub fn go_to_fetched_type_definition(
 fn go_to_fetched_definition_of_kind(
     kind: LinkDefinitionKind,
     editor: &mut Editor,
-    point: DisplayPoint,
+    point: PointForPosition,
     split: bool,
     cx: &mut ViewContext<Editor>,
 ) {
@@ -282,31 +589,40 @@ fn go_to_fetched_definition_of_kind(
     } else {
         editor.select(
             SelectPhase::Begin {
-                position: point,
+                position: point.next_valid,
                 add: false,
                 click_count: 1,
             },
             cx,
         );
 
+        if point.as_valid().is_some() {
             match kind {
                 LinkDefinitionKind::Symbol => editor.go_to_definition(&Default::default(), cx),
                 LinkDefinitionKind::Type => editor.go_to_type_definition(&Default::default(), cx),
             }
         }
     }
+}
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{editor_tests::init_test, test::editor_lsp_test_context::EditorLspTestContext};
+    use crate::{
+        display_map::ToDisplayPoint,
+        editor_tests::init_test,
+        inlay_hint_cache::tests::{cached_hint_labels, visible_hint_labels},
+        test::editor_lsp_test_context::EditorLspTestContext,
+    };
     use futures::StreamExt;
     use gpui::{
         platform::{self, Modifiers, ModifiersChangedEvent},
         View,
     };
     use indoc::indoc;
+    use language::language_settings::InlayHintSettings;
     use lsp::request::{GotoDefinition, GotoTypeDefinition};
+    use util::assert_set_eq;
 
     #[gpui::test]
     async fn test_link_go_to_type_definition(cx: &mut gpui::TestAppContext) {
@@ -355,7 +671,13 @@ mod tests {
 
         // Press cmd+shift to trigger highlight
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, true, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                true,
+                cx,
+            );
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -406,7 +728,7 @@ mod tests {
             });
 
         cx.update_editor(|editor, cx| {
-            go_to_fetched_type_definition(editor, hover_point, false, cx);
+            go_to_fetched_type_definition(editor, PointForPosition::valid(hover_point), false, cx);
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -461,7 +783,13 @@ mod tests {
         });
 
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -482,7 +810,7 @@ mod tests {
         "});
 
         // Response without source range still highlights word
-        cx.update_editor(|editor, _| editor.link_go_to_definition_state.last_mouse_location = None);
+        cx.update_editor(|editor, _| editor.link_go_to_definition_state.last_trigger_point = None);
         let mut requests = cx.handle_request::<GotoDefinition, _, _>(move |url, _, _| async move {
             Ok(Some(lsp::GotoDefinitionResponse::Link(vec![
                 lsp::LocationLink {
@@ -495,7 +823,13 @@ mod tests {
             ])))
         });
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -517,7 +851,13 @@ mod tests {
                 Ok(Some(lsp::GotoDefinitionResponse::Link(vec![])))
             });
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -534,7 +874,13 @@ mod tests {
             fn do_work() { teˇst(); }
         "});
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), false, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                false,
+                false,
+                cx,
+            );
         });
         cx.foreground().run_until_parked();
 
@@ -593,7 +939,13 @@ mod tests {
 
         // Moving the mouse restores the highlights.
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         cx.foreground().run_until_parked();
         cx.assert_editor_text_highlights::<LinkGoToDefinitionState>(indoc! {"
@@ -607,7 +959,13 @@ mod tests {
             fn do_work() { tesˇt(); }
         "});
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         cx.foreground().run_until_parked();
         cx.assert_editor_text_highlights::<LinkGoToDefinitionState>(indoc! {"
@@ -617,7 +975,7 @@ mod tests {
 
         // Cmd click with existing definition doesn't re-request and dismisses highlight
         cx.update_editor(|editor, cx| {
-            go_to_fetched_definition(editor, hover_point, false, cx);
+            go_to_fetched_definition(editor, PointForPosition::valid(hover_point), false, cx);
         });
         // Assert selection moved to to definition
         cx.lsp
@@ -626,6 +984,7 @@ mod tests {
                 // the cached location instead
                 Ok(Some(lsp::GotoDefinitionResponse::Link(vec![])))
             });
+        cx.foreground().run_until_parked();
         cx.assert_editor_state(indoc! {"
             fn «testˇ»() { do_work(); }
             fn do_work() { test(); }
@@ -658,7 +1017,7 @@ mod tests {
             ])))
         });
         cx.update_editor(|editor, cx| {
-            go_to_fetched_definition(editor, hover_point, false, cx);
+            go_to_fetched_definition(editor, PointForPosition::valid(hover_point), false, cx);
         });
         requests.next().await;
         cx.foreground().run_until_parked();
@@ -703,7 +1062,13 @@ mod tests {
             });
         });
         cx.update_editor(|editor, cx| {
-            update_go_to_definition_link(editor, Some(hover_point), true, false, cx);
+            update_go_to_definition_link(
+                editor,
+                Some(GoToDefinitionTrigger::Text(hover_point)),
+                true,
+                false,
+                cx,
+            );
         });
         cx.foreground().run_until_parked();
         assert!(requests.try_next().is_err());
@@ -713,4 +1078,217 @@ mod tests {
         "});
         cx.foreground().run_until_parked();
     }
+
+    #[gpui::test]
+    async fn test_link_go_to_inlay(cx: &mut gpui::TestAppContext) {
+        init_test(cx, |settings| {
+            settings.defaults.inlay_hints = Some(InlayHintSettings {
+                enabled: true,
+                show_type_hints: true,
+                show_parameter_hints: true,
+                show_other_hints: true,
+            })
+        });
+
+        let mut cx = EditorLspTestContext::new_rust(
+            lsp::ServerCapabilities {
+                inlay_hint_provider: Some(lsp::OneOf::Left(true)),
+                ..Default::default()
+            },
+            cx,
+        )
+        .await;
+        cx.set_state(indoc! {"
+            struct TestStruct;
+
+            fn main() {
+                let variableˇ = TestStruct;
+            }
+        "});
+        let hint_start_offset = cx.ranges(indoc! {"
+            struct TestStruct;
+
+            fn main() {
+                let variableˇ = TestStruct;
+            }
+        "})[0]
+            .start;
+        let hint_position = cx.to_lsp(hint_start_offset);
+        let target_range = cx.lsp_range(indoc! {"
+            struct «TestStruct»;
+
+            fn main() {
+                let variable = TestStruct;
+            }
+        "});
+
+        let expected_uri = cx.buffer_lsp_url.clone();
+        let hint_label = ": TestStruct";
+        cx.lsp
+            .handle_request::<lsp::request::InlayHintRequest, _, _>(move |params, _| {
+                let expected_uri = expected_uri.clone();
+                async move {
+                    assert_eq!(params.text_document.uri, expected_uri);
+                    Ok(Some(vec![lsp::InlayHint {
+                        position: hint_position,
+                        label: lsp::InlayHintLabel::LabelParts(vec![lsp::InlayHintLabelPart {
+                            value: hint_label.to_string(),
+                            location: Some(lsp::Location {
+                                uri: params.text_document.uri,
+                                range: target_range,
+                            }),
+                            ..Default::default()
+                        }]),
+                        kind: Some(lsp::InlayHintKind::TYPE),
+                        text_edits: None,
+                        tooltip: None,
+                        padding_left: Some(false),
+                        padding_right: Some(false),
+                        data: None,
+                    }]))
+                }
+            })
+            .next()
+            .await;
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            let expected_layers = vec![hint_label.to_string()];
+            assert_eq!(expected_layers, cached_hint_labels(editor));
+            assert_eq!(expected_layers, visible_hint_labels(editor, cx));
+        });
+
+        let inlay_range = cx
+            .ranges(indoc! {"
+            struct TestStruct;
+
+            fn main() {
+                let variable« »= TestStruct;
+            }
+        "})
+            .get(0)
+            .cloned()
+            .unwrap();
+        let hint_hover_position = cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let previous_valid = inlay_range.start.to_display_point(&snapshot);
+            let next_valid = inlay_range.end.to_display_point(&snapshot);
+            assert_eq!(previous_valid.row(), next_valid.row());
+            assert!(previous_valid.column() < next_valid.column());
+            let exact_unclipped = DisplayPoint::new(
+                previous_valid.row(),
+                previous_valid.column() + (hint_label.len() / 2) as u32,
+            );
+            PointForPosition {
+                previous_valid,
+                next_valid,
+                exact_unclipped,
+                column_overshoot_after_line_end: 0,
+            }
+        });
+        // Press cmd to trigger highlight
+        cx.update_editor(|editor, cx| {
+            update_inlay_link_and_hover_points(
+                &editor.snapshot(cx),
+                hint_hover_position,
+                editor,
+                true,
+                false,
+                cx,
+            );
+        });
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let actual_ranges = snapshot
+                .highlight_ranges::<LinkGoToDefinitionState>()
+                .map(|ranges| ranges.as_ref().clone().1)
+                .unwrap_or_default()
+                .into_iter()
+                .map(|range| match range {
+                    DocumentRange::Text(range) => {
+                        panic!("Unexpected regular text selection range {range:?}")
+                    }
+                    DocumentRange::Inlay(inlay_range) => inlay_range,
+                })
+                .collect::<Vec<_>>();
+
+            let buffer_snapshot = editor.buffer().update(cx, |buffer, cx| buffer.snapshot(cx));
+            let expected_highlight_start = snapshot.display_point_to_inlay_offset(
+                inlay_range.start.to_display_point(&snapshot),
+                Bias::Left,
+            );
+            let expected_ranges = vec![InlayRange {
+                inlay_position: buffer_snapshot.anchor_at(inlay_range.start, Bias::Right),
+                highlight_start: expected_highlight_start,
+                highlight_end: InlayOffset(expected_highlight_start.0 + hint_label.len()),
+            }];
+            assert_set_eq!(actual_ranges, expected_ranges);
+        });
+
+        // Unpress cmd causes highlight to go away
+        cx.update_editor(|editor, cx| {
+            editor.modifiers_changed(
+                &platform::ModifiersChangedEvent {
+                    modifiers: Modifiers {
+                        cmd: false,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                cx,
+            );
+        });
+        // Assert no link highlights
+        cx.update_editor(|editor, cx| {
+            let snapshot = editor.snapshot(cx);
+            let actual_ranges = snapshot
+                .highlight_ranges::<LinkGoToDefinitionState>()
+                .map(|ranges| ranges.as_ref().clone().1)
+                .unwrap_or_default()
+                .into_iter()
+                .map(|range| match range {
+                    DocumentRange::Text(range) => {
+                        panic!("Unexpected regular text selection range {range:?}")
+                    }
+                    DocumentRange::Inlay(inlay_range) => inlay_range,
+                })
+                .collect::<Vec<_>>();
+
+            assert!(actual_ranges.is_empty(), "When no cmd is pressed, should have no hint label selected, but got: {actual_ranges:?}");
+        });
+
+        // Cmd+click without existing definition requests and jumps
+        cx.update_editor(|editor, cx| {
+            editor.modifiers_changed(
+                &platform::ModifiersChangedEvent {
+                    modifiers: Modifiers {
+                        cmd: true,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                cx,
+            );
+            update_inlay_link_and_hover_points(
+                &editor.snapshot(cx),
+                hint_hover_position,
+                editor,
+                true,
+                false,
+                cx,
+            );
+        });
+        cx.foreground().run_until_parked();
+        cx.update_editor(|editor, cx| {
+            go_to_fetched_type_definition(editor, hint_hover_position, false, cx);
+        });
+        cx.foreground().run_until_parked();
+        cx.assert_editor_state(indoc! {"
+            struct «TestStructˇ»;
+
+            fn main() {
+                let variable = TestStruct;
+            }
+        "});
+    }
 }

crates/editor/src/movement.rs

@@ -756,7 +756,8 @@ mod tests {
             .select_font(family_id, &Default::default())
             .unwrap();
 
-        let buffer = cx.add_model(|cx| Buffer::new(0, "abc\ndefg\nhijkl\nmn", cx));
+        let buffer =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "abc\ndefg\nhijkl\nmn"));
         let multibuffer = cx.add_model(|cx| {
             let mut multibuffer = MultiBuffer::new(0);
             multibuffer.push_excerpts(

crates/editor/src/multi_buffer.rs

@@ -6,7 +6,7 @@ use clock::ReplicaId;
 use collections::{BTreeMap, Bound, HashMap, HashSet};
 use futures::{channel::mpsc, SinkExt};
 use git::diff::DiffHunk;
-use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
+use gpui::{AppContext, Entity, ModelContext, ModelHandle};
 pub use language::Completion;
 use language::{
     char_kind,
@@ -67,7 +67,9 @@ pub enum Event {
     ExcerptsEdited {
         ids: Vec<ExcerptId>,
     },
-    Edited,
+    Edited {
+        sigleton_buffer_edited: bool,
+    },
     Reloaded,
     DiffBaseChanged,
     LanguageChanged,
@@ -788,13 +790,13 @@ impl MultiBuffer {
 
     pub fn stream_excerpts_with_context_lines(
         &mut self,
-        excerpts: Vec<(ModelHandle<Buffer>, Vec<Range<text::Anchor>>)>,
+        buffer: ModelHandle<Buffer>,
+        ranges: Vec<Range<text::Anchor>>,
         context_line_count: u32,
         cx: &mut ModelContext<Self>,
-    ) -> (Task<()>, mpsc::Receiver<Range<Anchor>>) {
+    ) -> mpsc::Receiver<Range<Anchor>> {
         let (mut tx, rx) = mpsc::channel(256);
-        let task = cx.spawn(|this, mut cx| async move {
-            for (buffer, ranges) in excerpts {
+        cx.spawn(|this, mut cx| async move {
             let (buffer_id, buffer_snapshot) =
                 buffer.read_with(&cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
 
@@ -818,8 +820,7 @@ impl MultiBuffer {
                     this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
                 });
 
-                    for (excerpt_id, range_count) in
-                        excerpt_ids.into_iter().zip(range_counts.by_ref())
+                for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.by_ref())
                 {
                     for range in ranges.by_ref().take(range_count) {
                         let start = Anchor {
@@ -838,9 +839,10 @@ impl MultiBuffer {
                     }
                 }
             }
-            }
-        });
-        (task, rx)
+        })
+        .detach();
+
+        rx
     }
 
     pub fn push_excerpts<O>(
@@ -1022,7 +1024,9 @@ impl MultiBuffer {
             old: edit_start..edit_start,
             new: edit_start..edit_end,
         }]);
-        cx.emit(Event::Edited);
+        cx.emit(Event::Edited {
+            sigleton_buffer_edited: false,
+        });
         cx.emit(Event::ExcerptsAdded {
             buffer,
             predecessor: prev_excerpt_id,
@@ -1046,7 +1050,9 @@ impl MultiBuffer {
             old: 0..prev_len,
             new: 0..0,
         }]);
-        cx.emit(Event::Edited);
+        cx.emit(Event::Edited {
+            sigleton_buffer_edited: false,
+        });
         cx.emit(Event::ExcerptsRemoved { ids });
         cx.notify();
     }
@@ -1254,7 +1260,9 @@ impl MultiBuffer {
         }
 
         self.subscriptions.publish_mut(edits);
-        cx.emit(Event::Edited);
+        cx.emit(Event::Edited {
+            sigleton_buffer_edited: false,
+        });
         cx.emit(Event::ExcerptsRemoved { ids });
         cx.notify();
     }
@@ -1315,7 +1323,9 @@ impl MultiBuffer {
         cx: &mut ModelContext<Self>,
     ) {
         cx.emit(match event {
-            language::Event::Edited => Event::Edited,
+            language::Event::Edited => Event::Edited {
+                sigleton_buffer_edited: true,
+            },
             language::Event::DirtyChanged => Event::DirtyChanged,
             language::Event::Saved => Event::Saved,
             language::Event::FileHandleChanged => Event::FileHandleChanged,
@@ -1560,7 +1570,7 @@ impl MultiBuffer {
 #[cfg(any(test, feature = "test-support"))]
 impl MultiBuffer {
     pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> ModelHandle<Self> {
-        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text));
         cx.add_model(|cx| Self::singleton(buffer, cx))
     }
 
@@ -1570,7 +1580,7 @@ impl MultiBuffer {
     ) -> ModelHandle<Self> {
         let multi = cx.add_model(|_| Self::new(0));
         for (text, ranges) in excerpts {
-            let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
+            let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text));
             let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
                 context: range,
                 primary: None,
@@ -1662,7 +1672,7 @@ impl MultiBuffer {
             if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
                 let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
                     let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
-                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
+                    buffers.push(cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text)));
                     let buffer = buffers.last().unwrap().read(cx);
                     log::info!(
                         "Creating new buffer {} with text: {:?}",
@@ -2756,7 +2766,9 @@ impl MultiBufferSnapshot {
         // Get the ranges of the innermost pair of brackets.
         let mut result: Option<(Range<usize>, Range<usize>)> = None;
 
-        let Some(enclosing_bracket_ranges) = self.enclosing_bracket_ranges(range.clone()) else { return None; };
+        let Some(enclosing_bracket_ranges) = self.enclosing_bracket_ranges(range.clone()) else {
+            return None;
+        };
 
         for (open, close) in enclosing_bracket_ranges {
             let len = close.end - open.start;
@@ -4010,7 +4022,8 @@ mod tests {
 
     #[gpui::test]
     fn test_singleton(cx: &mut AppContext) {
-        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
+        let buffer =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(6, 6, 'a')));
         let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
 
         let snapshot = multibuffer.read(cx).snapshot(cx);
@@ -4037,7 +4050,7 @@ mod tests {
 
     #[gpui::test]
     fn test_remote(cx: &mut AppContext) {
-        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
+        let host_buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "a"));
         let guest_buffer = cx.add_model(|cx| {
             let state = host_buffer.read(cx).to_proto();
             let ops = cx
@@ -4068,15 +4081,17 @@ mod tests {
 
     #[gpui::test]
     fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
+        let buffer_1 =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(6, 6, 'a')));
+        let buffer_2 =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(6, 6, 'g')));
         let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
 
         let events = Rc::new(RefCell::new(Vec::<Event>::new()));
         multibuffer.update(cx, |_, cx| {
             let events = events.clone();
             cx.subscribe(&multibuffer, move |_, _, event, _| {
-                if let Event::Edited = event {
+                if let Event::Edited { .. } = event {
                     events.borrow_mut().push(event.clone())
                 }
             })
@@ -4131,7 +4146,17 @@ mod tests {
         // Adding excerpts emits an edited event.
         assert_eq!(
             events.borrow().as_slice(),
-            &[Event::Edited, Event::Edited, Event::Edited]
+            &[
+                Event::Edited {
+                    sigleton_buffer_edited: false
+                },
+                Event::Edited {
+                    sigleton_buffer_edited: false
+                },
+                Event::Edited {
+                    sigleton_buffer_edited: false
+                }
+            ]
         );
 
         let snapshot = multibuffer.read(cx).snapshot(cx);
@@ -4292,8 +4317,10 @@ mod tests {
 
     #[gpui::test]
     fn test_excerpt_events(cx: &mut AppContext) {
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(10, 3, 'a'), cx));
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(10, 3, 'm'), cx));
+        let buffer_1 =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(10, 3, 'a')));
+        let buffer_2 =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(10, 3, 'm')));
 
         let leader_multibuffer = cx.add_model(|_| MultiBuffer::new(0));
         let follower_multibuffer = cx.add_model(|_| MultiBuffer::new(0));
@@ -4310,7 +4337,7 @@ mod tests {
                         excerpts,
                     } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
                     Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
-                    Event::Edited => {
+                    Event::Edited { .. } => {
                         *follower_edit_event_count.borrow_mut() += 1;
                     }
                     _ => {}
@@ -4398,7 +4425,8 @@ mod tests {
 
     #[gpui::test]
     fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
-        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
+        let buffer =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(20, 3, 'a')));
         let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
         let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
             multibuffer.push_excerpts_with_context_lines(
@@ -4434,9 +4462,10 @@ mod tests {
 
     #[gpui::test]
     async fn test_stream_excerpts_with_context_lines(cx: &mut TestAppContext) {
-        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
+        let buffer =
+            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, sample_text(20, 3, 'a')));
         let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
-        let (task, anchor_ranges) = multibuffer.update(cx, |multibuffer, cx| {
+        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
             let snapshot = buffer.read(cx);
             let ranges = vec![
                 snapshot.anchor_before(Point::new(3, 2))..snapshot.anchor_before(Point::new(4, 2)),
@@ -4444,12 +4473,10 @@ mod tests {
                 snapshot.anchor_before(Point::new(15, 0))
                     ..snapshot.anchor_before(Point::new(15, 0)),
             ];
-            multibuffer.stream_excerpts_with_context_lines(vec![(buffer.clone(), ranges)], 2, cx)
+            multibuffer.stream_excerpts_with_context_lines(buffer.clone(), ranges, 2, cx)
         });
 
         let anchor_ranges = anchor_ranges.collect::<Vec<_>>().await;
-        // Ensure task is finished when stream completes.
-        task.await;
 
         let snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
         assert_eq!(
@@ -4482,7 +4509,7 @@ mod tests {
 
     #[gpui::test]
     fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
-        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "abcd"));
         let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
         let old_snapshot = multibuffer.read(cx).snapshot(cx);
         buffer.update(cx, |buffer, cx| {
@@ -4502,8 +4529,8 @@ mod tests {
 
     #[gpui::test]
     fn test_multibuffer_anchors(cx: &mut AppContext) {
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
+        let buffer_1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "abcd"));
+        let buffer_2 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "efghi"));
         let multibuffer = cx.add_model(|cx| {
             let mut multibuffer = MultiBuffer::new(0);
             multibuffer.push_excerpts(
@@ -4560,8 +4587,8 @@ mod tests {
 
     #[gpui::test]
     fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
+        let buffer_1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "abcd"));
+        let buffer_2 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "ABCDEFGHIJKLMNOP"));
         let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
 
         // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
@@ -4956,7 +4983,9 @@ mod tests {
                         let base_text = util::RandomCharIter::new(&mut rng)
                             .take(10)
                             .collect::<String>();
-                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
+                        buffers.push(
+                            cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, base_text)),
+                        );
                         buffers.last().unwrap()
                     } else {
                         buffers.choose(&mut rng).unwrap()
@@ -5297,8 +5326,8 @@ mod tests {
     fn test_history(cx: &mut AppContext) {
         cx.set_global(SettingsStore::test(cx));
 
-        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
-        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
+        let buffer_1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "1234"));
+        let buffer_2 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "5678"));
         let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
         let group_interval = multibuffer.read(cx).history.group_interval;
         multibuffer.update(cx, |multibuffer, cx| {

crates/editor/src/scroll/autoscroll.rs

@@ -65,47 +65,52 @@ impl Editor {
             self.set_scroll_position(scroll_position, cx);
         }
 
-        let (autoscroll, local) =
-            if let Some(autoscroll) = self.scroll_manager.autoscroll_request.take() {
-                autoscroll
-            } else {
+        let Some((autoscroll, local)) = self.scroll_manager.autoscroll_request.take() else {
             return false;
         };
 
-        let first_cursor_top;
-        let last_cursor_bottom;
+        let mut target_top;
+        let mut target_bottom;
         if let Some(highlighted_rows) = &self.highlighted_rows {
-            first_cursor_top = highlighted_rows.start as f32;
-            last_cursor_bottom = first_cursor_top + 1.;
-        } else if autoscroll == Autoscroll::newest() {
-            let newest_selection = self.selections.newest::<Point>(cx);
-            first_cursor_top = newest_selection.head().to_display_point(&display_map).row() as f32;
-            last_cursor_bottom = first_cursor_top + 1.;
+            target_top = highlighted_rows.start as f32;
+            target_bottom = target_top + 1.;
         } else {
             let selections = self.selections.all::<Point>(cx);
-            first_cursor_top = selections
+            target_top = selections
                 .first()
                 .unwrap()
                 .head()
                 .to_display_point(&display_map)
                 .row() as f32;
-            last_cursor_bottom = selections
+            target_bottom = selections
                 .last()
                 .unwrap()
                 .head()
                 .to_display_point(&display_map)
                 .row() as f32
                 + 1.0;
+
+            // If the selections can't all fit on screen, scroll to the newest.
+            if autoscroll == Autoscroll::newest()
+                || autoscroll == Autoscroll::fit() && target_bottom - target_top > visible_lines
+            {
+                let newest_selection_top = selections
+                    .iter()
+                    .max_by_key(|s| s.id)
+                    .unwrap()
+                    .head()
+                    .to_display_point(&display_map)
+                    .row() as f32;
+                target_top = newest_selection_top;
+                target_bottom = newest_selection_top + 1.;
+            }
         }
 
         let margin = if matches!(self.mode, EditorMode::AutoHeight { .. }) {
             0.
         } else {
-            ((visible_lines - (last_cursor_bottom - first_cursor_top)) / 2.0).floor()
+            ((visible_lines - (target_bottom - target_top)) / 2.0).floor()
         };
-        if margin < 0.0 {
-            return false;
-        }
 
         let strategy = match autoscroll {
             Autoscroll::Strategy(strategy) => strategy,
@@ -113,8 +118,8 @@ impl Editor {
                 let last_autoscroll = &self.scroll_manager.last_autoscroll;
                 if let Some(last_autoscroll) = last_autoscroll {
                     if self.scroll_manager.anchor.offset == last_autoscroll.0
-                        && first_cursor_top == last_autoscroll.1
-                        && last_cursor_bottom == last_autoscroll.2
+                        && target_top == last_autoscroll.1
+                        && target_bottom == last_autoscroll.2
                     {
                         last_autoscroll.3.next()
                     } else {
@@ -129,37 +134,41 @@ impl Editor {
         match strategy {
             AutoscrollStrategy::Fit | AutoscrollStrategy::Newest => {
                 let margin = margin.min(self.scroll_manager.vertical_scroll_margin);
-                let target_top = (first_cursor_top - margin).max(0.0);
-                let target_bottom = last_cursor_bottom + margin;
+                let target_top = (target_top - margin).max(0.0);
+                let target_bottom = target_bottom + margin;
                 let start_row = scroll_position.y();
                 let end_row = start_row + visible_lines;
 
-                if target_top < start_row {
+                let needs_scroll_up = target_top < start_row;
+                let needs_scroll_down = target_bottom >= end_row;
+
+                if needs_scroll_up && !needs_scroll_down {
                     scroll_position.set_y(target_top);
                     self.set_scroll_position_internal(scroll_position, local, true, cx);
-                } else if target_bottom >= end_row {
+                }
+                if !needs_scroll_up && needs_scroll_down {
                     scroll_position.set_y(target_bottom - visible_lines);
                     self.set_scroll_position_internal(scroll_position, local, true, cx);
                 }
             }
             AutoscrollStrategy::Center => {
-                scroll_position.set_y((first_cursor_top - margin).max(0.0));
+                scroll_position.set_y((target_top - margin).max(0.0));
                 self.set_scroll_position_internal(scroll_position, local, true, cx);
             }
             AutoscrollStrategy::Top => {
-                scroll_position.set_y((first_cursor_top).max(0.0));
+                scroll_position.set_y((target_top).max(0.0));
                 self.set_scroll_position_internal(scroll_position, local, true, cx);
             }
             AutoscrollStrategy::Bottom => {
-                scroll_position.set_y((last_cursor_bottom - visible_lines).max(0.0));
+                scroll_position.set_y((target_bottom - visible_lines).max(0.0));
                 self.set_scroll_position_internal(scroll_position, local, true, cx);
             }
         }
 
         self.scroll_manager.last_autoscroll = Some((
             self.scroll_manager.anchor.offset,
-            first_cursor_top,
-            last_cursor_bottom,
+            target_top,
+            target_bottom,
             strategy,
         ));
 

crates/editor/src/test/editor_test_context.rs

@@ -225,6 +225,7 @@ impl<'a> EditorTestContext<'a> {
                 .map(|h| h.1.clone())
                 .unwrap_or_default()
                 .into_iter()
+                .filter_map(|range| range.as_text_range())
                 .map(|range| range.to_offset(&snapshot.buffer_snapshot))
                 .collect()
         });
@@ -240,6 +241,7 @@ impl<'a> EditorTestContext<'a> {
             .map(|ranges| ranges.as_ref().clone().1)
             .unwrap_or_default()
             .into_iter()
+            .filter_map(|range| range.as_text_range())
             .map(|range| range.to_offset(&snapshot.buffer_snapshot))
             .collect();
         assert_set_eq!(actual_ranges, expected_ranges);

crates/feature_flags/Cargo.toml

@@ -1,11 +1,11 @@
 [package]
-name = "staff_mode"
+name = "feature_flags"
 version = "0.1.0"
 edition = "2021"
 publish = false
 
 [lib]
-path = "src/staff_mode.rs"
+path = "src/feature_flags.rs"
 
 [dependencies]
 gpui = { path = "../gpui" }

crates/feature_flags/src/feature_flags.rs

@@ -0,0 +1,79 @@
+use gpui::{AppContext, Subscription, ViewContext};
+
+#[derive(Default)]
+struct FeatureFlags {
+    flags: Vec<String>,
+    staff: bool,
+}
+
+impl FeatureFlags {
+    fn has_flag(&self, flag: &str) -> bool {
+        self.staff || self.flags.iter().find(|f| f.as_str() == flag).is_some()
+    }
+}
+
+pub trait FeatureFlag {
+    const NAME: &'static str;
+}
+
+pub enum ChannelsAlpha {}
+
+impl FeatureFlag for ChannelsAlpha {
+    const NAME: &'static str = "channels_alpha";
+}
+
+pub trait FeatureFlagViewExt<V: 'static> {
+    fn observe_flag<T: FeatureFlag, F>(&mut self, callback: F) -> Subscription
+    where
+        F: Fn(bool, &mut V, &mut ViewContext<V>) + 'static;
+}
+
+impl<V: 'static> FeatureFlagViewExt<V> for ViewContext<'_, '_, V> {
+    fn observe_flag<T: FeatureFlag, F>(&mut self, callback: F) -> Subscription
+    where
+        F: Fn(bool, &mut V, &mut ViewContext<V>) + 'static,
+    {
+        self.observe_global::<FeatureFlags, _>(move |v, cx| {
+            let feature_flags = cx.global::<FeatureFlags>();
+            callback(feature_flags.has_flag(<T as FeatureFlag>::NAME), v, cx);
+        })
+    }
+}
+
+pub trait FeatureFlagAppExt {
+    fn update_flags(&mut self, staff: bool, flags: Vec<String>);
+    fn set_staff(&mut self, staff: bool);
+    fn has_flag<T: FeatureFlag>(&self) -> bool;
+    fn is_staff(&self) -> bool;
+}
+
+impl FeatureFlagAppExt for AppContext {
+    fn update_flags(&mut self, staff: bool, flags: Vec<String>) {
+        self.update_default_global::<FeatureFlags, _, _>(|feature_flags, _| {
+            feature_flags.staff = staff;
+            feature_flags.flags = flags;
+        })
+    }
+
+    fn set_staff(&mut self, staff: bool) {
+        self.update_default_global::<FeatureFlags, _, _>(|feature_flags, _| {
+            feature_flags.staff = staff;
+        })
+    }
+
+    fn has_flag<T: FeatureFlag>(&self) -> bool {
+        if self.has_global::<FeatureFlags>() {
+            self.global::<FeatureFlags>().has_flag(T::NAME)
+        } else {
+            false
+        }
+    }
+
+    fn is_staff(&self) -> bool {
+        if self.has_global::<FeatureFlags>() {
+            return self.global::<FeatureFlags>().staff;
+        } else {
+            false
+        }
+    }
+}

crates/gpui/examples/components.rs

@@ -2,7 +2,7 @@ use button_component::Button;
 
 use gpui::{
     color::Color,
-    elements::{Component, ContainerStyle, Flex, Label, ParentElement},
+    elements::{ContainerStyle, Flex, Label, ParentElement, StatefulComponent},
     fonts::{self, TextStyle},
     platform::WindowOptions,
     AnyElement, App, Element, Entity, View, ViewContext,
@@ -114,7 +114,7 @@ mod theme {
 // Component creation:
 mod toggleable_button {
     use gpui::{
-        elements::{Component, ContainerStyle, LabelStyle},
+        elements::{ContainerStyle, LabelStyle, StatefulComponent},
         scene::MouseClick,
         EventContext, View,
     };
@@ -156,7 +156,7 @@ mod toggleable_button {
         }
     }
 
-    impl<V: View> Component<V> for ToggleableButton<V> {
+    impl<V: View> StatefulComponent<V> for ToggleableButton<V> {
         fn render(self, v: &mut V, cx: &mut gpui::ViewContext<V>) -> gpui::AnyElement<V> {
             let button = if let Some(style) = self.style {
                 self.button.with_style(*style.style_for(self.active))
@@ -171,7 +171,7 @@ mod toggleable_button {
 mod button_component {
 
     use gpui::{
-        elements::{Component, ContainerStyle, Label, LabelStyle, MouseEventHandler},
+        elements::{ContainerStyle, Label, LabelStyle, MouseEventHandler, StatefulComponent},
         platform::MouseButton,
         scene::MouseClick,
         AnyElement, Element, EventContext, TypeTag, View, ViewContext,
@@ -212,7 +212,7 @@ mod button_component {
         }
     }
 
-    impl<V: View> Component<V> for Button<V> {
+    impl<V: View> StatefulComponent<V> for Button<V> {
         fn render(self, _: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V> {
             let click_handler = self.click_handler;
 

crates/gpui/src/app.rs

@@ -3299,15 +3299,15 @@ impl<'a, 'b, V: 'static> ViewContext<'a, 'b, V> {
         let region_id = MouseRegionId::new(tag, self.view_id, region_id);
         MouseState {
             hovered: self.window.hovered_region_ids.contains(&region_id),
-            clicked: if let Some((clicked_region_id, button)) = self.window.clicked_region {
-                if region_id == clicked_region_id {
-                    Some(button)
-                } else {
-                    None
-                }
-            } else {
-                None
-            },
+            mouse_down: !self.window.clicked_region_ids.is_empty(),
+            clicked: self
+                .window
+                .clicked_region_ids
+                .iter()
+                .find(|click_region_id| **click_region_id == region_id)
+                // If we've gotten here, there should always be a clicked region.
+                // But let's be defensive and return None if there isn't.
+                .and_then(|_| self.window.clicked_region.map(|(_, button)| button)),
             accessed_hovered: false,
             accessed_clicked: false,
         }
@@ -3798,14 +3798,20 @@ impl<'a, T> DerefMut for Reference<'a, T> {
 pub struct MouseState {
     pub(crate) hovered: bool,
     pub(crate) clicked: Option<MouseButton>,
+    pub(crate) mouse_down: bool,
     pub(crate) accessed_hovered: bool,
     pub(crate) accessed_clicked: bool,
 }
 
 impl MouseState {
+    pub fn dragging(&mut self) -> bool {
+        self.accessed_hovered = true;
+        self.hovered && self.mouse_down
+    }
+
     pub fn hovered(&mut self) -> bool {
         self.accessed_hovered = true;
-        self.hovered
+        self.hovered && (!self.mouse_down || self.clicked.is_some())
     }
 
     pub fn clicked(&mut self) -> Option<MouseButton> {
@@ -4656,12 +4662,13 @@ impl AnyWeakModelHandle {
     }
 }
 
-#[derive(Copy)]
 pub struct WeakViewHandle<T> {
     any_handle: AnyWeakViewHandle,
     view_type: PhantomData<T>,
 }
 
+impl<T> Copy for WeakViewHandle<T> {}
+
 impl<T> Debug for WeakViewHandle<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct(&format!("WeakViewHandle<{}>", type_name::<T>()))

crates/gpui/src/app/window.rs

@@ -624,7 +624,8 @@ impl<'a> WindowContext<'a> {
                     }
                 }
 
-                if self
+                if pressed_button.is_none()
+                    && self
                         .window
                         .platform_window
                         .is_topmost_for_position(*position)
@@ -791,6 +792,11 @@ impl<'a> WindowContext<'a> {
                             if clicked_region_ids.contains(&mouse_region.id()) {
                                 if mouse_region.bounds.contains_point(self.mouse_position()) {
                                     valid_regions.push(mouse_region.clone());
+                                } else {
+                                    // Let the view know that it hasn't been clicked anymore
+                                    if mouse_region.notify_on_click {
+                                        notified_views.insert(mouse_region.id().view_id());
+                                    }
                                 }
                             }
                         }

crates/gpui/src/elements.rs

@@ -234,6 +234,27 @@ pub trait Element<V: 'static>: 'static {
     {
         MouseEventHandler::for_child::<Tag>(self.into_any(), region_id)
     }
+
+    fn component(self) -> StatelessElementAdapter
+    where
+        Self: Sized,
+    {
+        StatelessElementAdapter::new(self.into_any())
+    }
+
+    fn stateful_component(self) -> StatefulElementAdapter<V>
+    where
+        Self: Sized,
+    {
+        StatefulElementAdapter::new(self.into_any())
+    }
+
+    fn styleable_component(self) -> StylableAdapter<StatelessElementAdapter>
+    where
+        Self: Sized,
+    {
+        StatelessElementAdapter::new(self.into_any()).stylable()
+    }
 }
 
 trait AnyElementState<V> {

crates/gpui/src/elements/component.rs

@@ -1,79 +1,81 @@
-use std::marker::PhantomData;
+use std::{any::Any, marker::PhantomData};
 
 use pathfinder_geometry::{rect::RectF, vector::Vector2F};
 
 use crate::{
-    AnyElement, Element, LayoutContext, PaintContext, SceneBuilder, SizeConstraint, View,
-    ViewContext,
+    AnyElement, Element, LayoutContext, PaintContext, SceneBuilder, SizeConstraint, ViewContext,
 };
 
 use super::Empty;
 
-pub trait GeneralComponent {
-    fn render<V: View>(self, v: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V>;
-    fn element<V: View>(self) -> ComponentAdapter<V, Self>
+/// The core stateless component trait, simply rendering an element tree
+pub trait Component {
+    fn render<V: 'static>(self, cx: &mut ViewContext<V>) -> AnyElement<V>;
+
+    fn element<V: 'static>(self) -> ComponentAdapter<V, Self>
     where
         Self: Sized,
     {
         ComponentAdapter::new(self)
     }
+
+    fn stylable(self) -> StylableAdapter<Self>
+    where
+        Self: Sized,
+    {
+        StylableAdapter::new(self)
     }
 
-pub trait StyleableComponent {
+    fn stateful<V: 'static>(self) -> StatefulAdapter<Self, V>
+    where
+        Self: Sized,
+    {
+        StatefulAdapter::new(self)
+    }
+}
+
+/// Allows a a component's styles to be rebound in a simple way.
+pub trait Stylable: Component {
     type Style: Clone;
-    type Output: GeneralComponent;
+
+    fn with_style(self, style: Self::Style) -> Self;
+}
+
+/// This trait models the typestate pattern for a component's style,
+/// enforcing at compile time that a component is only usable after
+/// it has been styled while still allowing for late binding of the
+/// styling information
+pub trait SafeStylable {
+    type Style: Clone;
+    type Output: Component;
 
     fn with_style(self, style: Self::Style) -> Self::Output;
 }
 
-impl GeneralComponent for () {
-    fn render<V: View>(self, _: &mut V, _: &mut ViewContext<V>) -> AnyElement<V> {
-        Empty::new().into_any()
+/// All stylable components can trivially implement SafeStylable
+impl<C: Stylable> SafeStylable for C {
+    type Style = C::Style;
+
+    type Output = C;
+
+    fn with_style(self, style: Self::Style) -> Self::Output {
+        self.with_style(style)
     }
 }
 
-impl StyleableComponent for () {
-    type Style = ();
-    type Output = ();
-
-    fn with_style(self, _: Self::Style) -> Self::Output {
-        ()
-    }
-}
-
-pub trait Component<V: View> {
-    fn render(self, v: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V>;
-
-    fn element(self) -> ComponentAdapter<V, Self>
-    where
-        Self: Sized,
-    {
-        ComponentAdapter::new(self)
-    }
-}
-
-impl<V: View, C: GeneralComponent> Component<V> for C {
-    fn render(self, v: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V> {
-        self.render(v, cx)
-    }
-}
-
-// StylableComponent -> GeneralComponent
-pub struct StylableComponentAdapter<C: Component<V>, V: View> {
+/// Allows converting an unstylable component into a stylable one
+/// by using `()` as the style type
+pub struct StylableAdapter<C: Component> {
     component: C,
-    phantom: std::marker::PhantomData<V>,
 }
 
-impl<C: Component<V>, V: View> StylableComponentAdapter<C, V> {
+impl<C: Component> StylableAdapter<C> {
     pub fn new(component: C) -> Self {
-        Self {
-            component,
-            phantom: std::marker::PhantomData,
-        }
+        Self { component }
     }
 }
 
-impl<C: GeneralComponent, V: View> StyleableComponent for StylableComponentAdapter<C, V> {
+impl<C: Component> SafeStylable for StylableAdapter<C> {
     type Style = ();
 
     type Output = C;
@@ -83,13 +85,150 @@ impl<C: GeneralComponent, V: View> StyleableComponent for StylableComponentAdapt
     }
 }
 
-// Element -> Component
-pub struct ElementAdapter<V: View> {
+/// This is a secondary trait for components that can be styled
+/// which rely on their view's state. This is useful for components that, for example,
+/// want to take click handler callbacks Unfortunately, the generic bound on the
+/// Component trait makes it incompatible with the stateless components above.
+// So let's just replicate them for now
+pub trait StatefulComponent<V: 'static> {
+    fn render(self, v: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V>;
+
+    fn element(self) -> ComponentAdapter<V, Self>
+    where
+        Self: Sized,
+    {
+        ComponentAdapter::new(self)
+    }
+
+    fn styleable(self) -> StatefulStylableAdapter<Self, V>
+    where
+        Self: Sized,
+    {
+        StatefulStylableAdapter::new(self)
+    }
+
+    fn stateless(self) -> StatelessElementAdapter
+    where
+        Self: Sized + 'static,
+    {
+        StatelessElementAdapter::new(self.element().into_any())
+    }
+}
+
+/// It is trivial to convert stateless components to stateful components, so lets
+/// do so en masse. Note that the reverse is impossible without a helper.
+impl<V: 'static, C: Component> StatefulComponent<V> for C {
+    fn render(self, _: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V> {
+        self.render(cx)
+    }
+}
+
+/// Same as stylable, but generic over a view type
+pub trait StatefulStylable<V: 'static>: StatefulComponent<V> {
+    type Style: Clone;
+
+    fn with_style(self, style: Self::Style) -> Self;
+}
+
+/// Same as SafeStylable, but generic over a view type
+pub trait StatefulSafeStylable<V: 'static> {
+    type Style: Clone;
+    type Output: StatefulComponent<V>;
+
+    fn with_style(self, style: Self::Style) -> Self::Output;
+}
+
+/// Converting from stateless to stateful
+impl<V: 'static, C: SafeStylable> StatefulSafeStylable<V> for C {
+    type Style = C::Style;
+
+    type Output = C::Output;
+
+    fn with_style(self, style: Self::Style) -> Self::Output {
+        self.with_style(style)
+    }
+}
+
+// A helper for converting stateless components into stateful ones
+pub struct StatefulAdapter<C, V> {
+    component: C,
+    phantom: std::marker::PhantomData<V>,
+}
+
+impl<C: Component, V: 'static> StatefulAdapter<C, V> {
+    pub fn new(component: C) -> Self {
+        Self {
+            component,
+            phantom: std::marker::PhantomData,
+        }
+    }
+}
+
+impl<C: Component, V: 'static> StatefulComponent<V> for StatefulAdapter<C, V> {
+    fn render(self, _: &mut V, cx: &mut ViewContext<V>) -> AnyElement<V> {
+        self.component.render(cx)
+    }
+}
+
+// A helper for converting stateful but style-less components into stylable ones
+// by using `()` as the style type
+pub struct StatefulStylableAdapter<C: StatefulComponent<V>, V: 'static> {
+    component: C,
+    phantom: std::marker::PhantomData<V>,
+}
+
+impl<C: StatefulComponent<V>, V: 'static> StatefulStylableAdapter<C, V> {
+    pub fn new(component: C) -> Self {
+        Self {
+            component,
+            phantom: std::marker::PhantomData,
+        }
+    }
+}
+
+impl<C: StatefulComponent<V>, V: 'static> StatefulSafeStylable<V>
+    for StatefulStylableAdapter<C, V>
+{
+    type Style = ();
+
+    type Output = C;
+
+    fn with_style(self, _: Self::Style) -> Self::Output {
+        self.component
+    }
+}
+
+/// A way of erasing the view generic from an element, useful
+/// for wrapping up an explicit element tree into stateless
+/// components
+pub struct StatelessElementAdapter {
+    element: Box<dyn Any>,
+}
+
+impl StatelessElementAdapter {
+    pub fn new<V: 'static>(element: AnyElement<V>) -> Self {
+        StatelessElementAdapter {
+            element: Box::new(element) as Box<dyn Any>,
+        }
+    }
+}
+
+impl Component for StatelessElementAdapter {
+    fn render<V: 'static>(self, _: &mut ViewContext<V>) -> AnyElement<V> {
+        *self
+            .element
+            .downcast::<AnyElement<V>>()
+            .expect("Don't move elements out of their view :(")
+    }
+}
+
+// For converting elements into stateful components
+pub struct StatefulElementAdapter<V: 'static> {
     element: AnyElement<V>,
     _phantom: std::marker::PhantomData<V>,
 }
 
-impl<V: View> ElementAdapter<V> {
+impl<V: 'static> StatefulElementAdapter<V> {
     pub fn new(element: AnyElement<V>) -> Self {
         Self {
             element,
@@ -98,20 +237,35 @@ impl<V: View> ElementAdapter<V> {
     }
 }
 
-impl<V: View> Component<V> for ElementAdapter<V> {
+impl<V: 'static> StatefulComponent<V> for StatefulElementAdapter<V> {
     fn render(self, _: &mut V, _: &mut ViewContext<V>) -> AnyElement<V> {
         self.element
     }
 }
 
-// Component -> Element
-pub struct ComponentAdapter<V: View, E> {
+/// A convenient shorthand for creating an empty component.
+impl Component for () {
+    fn render<V: 'static>(self, _: &mut ViewContext<V>) -> AnyElement<V> {
+        Empty::new().into_any()
+    }
+}
+
+impl Stylable for () {
+    type Style = ();
+
+    fn with_style(self, _: Self::Style) -> Self {
+        ()
+    }
+}
+
+// For converting components back into Elements
+pub struct ComponentAdapter<V: 'static, E> {
     component: Option<E>,
     element: Option<AnyElement<V>>,
     phantom: PhantomData<V>,
 }
 
-impl<E, V: View> ComponentAdapter<V, E> {
+impl<E, V: 'static> ComponentAdapter<V, E> {
     pub fn new(e: E) -> Self {
         Self {
             component: Some(e),
@@ -121,7 +275,7 @@ impl<E, V: View> ComponentAdapter<V, E> {
     }
 }
 
-impl<V: View, C: Component<V> + 'static> Element<V> for ComponentAdapter<V, C> {
+impl<V: 'static, C: StatefulComponent<V> + 'static> Element<V> for ComponentAdapter<V, C> {
     type LayoutState = ();
 
     type PaintState = ();
@@ -184,6 +338,7 @@ impl<V: View, C: Component<V> + 'static> Element<V> for ComponentAdapter<V, C> {
     ) -> serde_json::Value {
         serde_json::json!({
             "type": "ComponentAdapter",
+            "component": std::any::type_name::<C>(),
             "child": self.element.as_ref().map(|el| el.debug(view, cx)),
         })
     }

crates/gpui/src/elements/container.rs

@@ -44,6 +44,14 @@ impl ContainerStyle {
             ..Default::default()
         }
     }
+
+    pub fn additional_length(&self) -> f32 {
+        self.padding.left
+            + self.padding.right
+            + self.border.width * 2.
+            + self.margin.left
+            + self.margin.right
+    }
 }
 
 pub struct Container<V> {

crates/gpui/src/elements/flex.rs

@@ -22,6 +22,7 @@ pub struct Flex<V> {
     children: Vec<AnyElement<V>>,
     scroll_state: Option<(ElementStateHandle<Rc<ScrollState>>, usize)>,
     child_alignment: f32,
+    spacing: f32,
 }
 
 impl<V: 'static> Flex<V> {
@@ -31,6 +32,7 @@ impl<V: 'static> Flex<V> {
             children: Default::default(),
             scroll_state: None,
             child_alignment: -1.,
+            spacing: 0.,
         }
     }
 
@@ -51,6 +53,11 @@ impl<V: 'static> Flex<V> {
         self
     }
 
+    pub fn with_spacing(mut self, spacing: f32) -> Self {
+        self.spacing = spacing;
+        self
+    }
+
     pub fn scrollable<Tag>(
         mut self,
         element_id: usize,
@@ -81,7 +88,7 @@ impl<V: 'static> Flex<V> {
         cx: &mut LayoutContext<V>,
     ) {
         let cross_axis = self.axis.invert();
-        for child in &mut self.children {
+        for child in self.children.iter_mut() {
             if let Some(metadata) = child.metadata::<FlexParentData>() {
                 if let Some((flex, expanded)) = metadata.flex {
                     if expanded != layout_expanded {
@@ -132,12 +139,12 @@ impl<V: 'static> Element<V> for Flex<V> {
         cx: &mut LayoutContext<V>,
     ) -> (Vector2F, Self::LayoutState) {
         let mut total_flex = None;
-        let mut fixed_space = 0.0;
+        let mut fixed_space = self.children.len().saturating_sub(1) as f32 * self.spacing;
         let mut contains_float = false;
 
         let cross_axis = self.axis.invert();
         let mut cross_axis_max: f32 = 0.0;
-        for child in &mut self.children {
+        for child in self.children.iter_mut() {
             let metadata = child.metadata::<FlexParentData>();
             contains_float |= metadata.map_or(false, |metadata| metadata.float);
 
@@ -315,7 +322,7 @@ impl<V: 'static> Element<V> for Flex<V> {
             }
         }
 
-        for child in &mut self.children {
+        for child in self.children.iter_mut() {
             if remaining_space > 0. {
                 if let Some(metadata) = child.metadata::<FlexParentData>() {
                     if metadata.float {
@@ -354,8 +361,8 @@ impl<V: 'static> Element<V> for Flex<V> {
             child.paint(scene, aligned_child_origin, visible_bounds, view, cx);
 
             match self.axis {
-                Axis::Horizontal => child_origin += vec2f(child.size().x(), 0.0),
-                Axis::Vertical => child_origin += vec2f(0.0, child.size().y()),
+                Axis::Horizontal => child_origin += vec2f(child.size().x() + self.spacing, 0.0),
+                Axis::Vertical => child_origin += vec2f(0.0, child.size().y() + self.spacing),
             }
         }
 

crates/gpui/src/keymap_matcher/keymap_context.rs

@@ -67,7 +67,9 @@ impl KeymapContextPredicate {
     }
 
     pub fn eval(&self, contexts: &[KeymapContext]) -> bool {
-        let Some(context) = contexts.first() else { return false };
+        let Some(context) = contexts.first() else {
+            return false;
+        };
         match self {
             Self::Identifier(name) => (&context.set).contains(name.as_str()),
             Self::Equal(left, right) => context

crates/language/src/buffer.rs

@@ -14,7 +14,7 @@ use crate::{
     CodeLabel, LanguageScope, Outline,
 };
 use anyhow::{anyhow, Result};
-use clock::ReplicaId;
+pub use clock::ReplicaId;
 use fs::LineEnding;
 use futures::FutureExt as _;
 use gpui::{fonts::HighlightStyle, AppContext, Entity, ModelContext, Task};
@@ -347,13 +347,17 @@ impl CharKind {
 }
 
 impl Buffer {
-    pub fn new<T: Into<String>>(
-        replica_id: ReplicaId,
-        base_text: T,
-        cx: &mut ModelContext<Self>,
-    ) -> Self {
+    pub fn new<T: Into<String>>(replica_id: ReplicaId, id: u64, base_text: T) -> Self {
         Self::build(
-            TextBuffer::new(replica_id, cx.model_id() as u64, base_text.into()),
+            TextBuffer::new(replica_id, id, base_text.into()),
+            None,
+            None,
+        )
+    }
+
+    pub fn remote(remote_id: u64, replica_id: ReplicaId, base_text: String) -> Self {
+        Self::build(
+            TextBuffer::new(replica_id, remote_id, base_text),
             None,
             None,
         )
@@ -2476,7 +2480,9 @@ impl BufferSnapshot {
 
                 matches.advance();
 
-                let Some((open, close)) = open.zip(close) else { continue };
+                let Some((open, close)) = open.zip(close) else {
+                    continue;
+                };
 
                 let bracket_range = open.start..=close.end;
                 if !bracket_range.overlaps(&range) {

crates/language/src/buffer_tests.rs

@@ -43,8 +43,8 @@ fn test_line_endings(cx: &mut gpui::AppContext) {
     init_settings(cx, |_| {});
 
     cx.add_model(|cx| {
-        let mut buffer =
-            Buffer::new(0, "one\r\ntwo\rthree", cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer = Buffer::new(0, cx.model_id() as u64, "one\r\ntwo\rthree")
+            .with_language(Arc::new(rust_lang()), cx);
         assert_eq!(buffer.text(), "one\ntwo\nthree");
         assert_eq!(buffer.line_ending(), LineEnding::Windows);
 
@@ -138,8 +138,8 @@ fn test_edit_events(cx: &mut gpui::AppContext) {
     let buffer_1_events = Rc::new(RefCell::new(Vec::new()));
     let buffer_2_events = Rc::new(RefCell::new(Vec::new()));
 
-    let buffer1 = cx.add_model(|cx| Buffer::new(0, "abcdef", cx));
-    let buffer2 = cx.add_model(|cx| Buffer::new(1, "abcdef", cx));
+    let buffer1 = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, "abcdef"));
+    let buffer2 = cx.add_model(|cx| Buffer::new(1, cx.model_id() as u64, "abcdef"));
     let buffer1_ops = Rc::new(RefCell::new(Vec::new()));
     buffer1.update(cx, {
         let buffer1_ops = buffer1_ops.clone();
@@ -222,7 +222,7 @@ fn test_edit_events(cx: &mut gpui::AppContext) {
 #[gpui::test]
 async fn test_apply_diff(cx: &mut gpui::TestAppContext) {
     let text = "a\nbb\nccc\ndddd\neeeee\nffffff\n";
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text));
     let anchor = buffer.read_with(cx, |buffer, _| buffer.anchor_before(Point::new(3, 3)));
 
     let text = "a\nccc\ndddd\nffffff\n";
@@ -254,7 +254,7 @@ async fn test_normalize_whitespace(cx: &mut gpui::TestAppContext) {
     ]
     .join("\n");
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
+    let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, text));
 
     // Spawn a task to format the buffer's whitespace.
     // Pause so that the foratting task starts running.
@@ -318,8 +318,9 @@ async fn test_normalize_whitespace(cx: &mut gpui::TestAppContext) {
 #[gpui::test]
 async fn test_reparse(cx: &mut gpui::TestAppContext) {
     let text = "fn a() {}";
-    let buffer =
-        cx.add_model(|cx| Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx));
+    let buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx)
+    });
 
     // Wait for the initial text to parse
     buffer.condition(cx, |buffer, _| !buffer.is_parsing()).await;
@@ -443,7 +444,8 @@ async fn test_reparse(cx: &mut gpui::TestAppContext) {
 #[gpui::test]
 async fn test_resetting_language(cx: &mut gpui::TestAppContext) {
     let buffer = cx.add_model(|cx| {
-        let mut buffer = Buffer::new(0, "{}", cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, "{}").with_language(Arc::new(rust_lang()), cx);
         buffer.set_sync_parse_timeout(Duration::ZERO);
         buffer
     });
@@ -491,8 +493,9 @@ async fn test_outline(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer =
-        cx.add_model(|cx| Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx));
+    let buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx)
+    });
     let outline = buffer
         .read_with(cx, |buffer, _| buffer.snapshot().outline(None))
         .unwrap();
@@ -576,8 +579,9 @@ async fn test_outline_nodes_with_newlines(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer =
-        cx.add_model(|cx| Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx));
+    let buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx)
+    });
     let outline = buffer
         .read_with(cx, |buffer, _| buffer.snapshot().outline(None))
         .unwrap();
@@ -613,7 +617,9 @@ async fn test_outline_with_extra_context(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer = cx.add_model(|cx| Buffer::new(0, text, cx).with_language(Arc::new(language), cx));
+    let buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(language), cx)
+    });
     let snapshot = buffer.read_with(cx, |buffer, _| buffer.snapshot());
 
     // extra context nodes are included in the outline.
@@ -655,8 +661,9 @@ async fn test_symbols_containing(cx: &mut gpui::TestAppContext) {
     "#
     .unindent();
 
-    let buffer =
-        cx.add_model(|cx| Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx));
+    let buffer = cx.add_model(|cx| {
+        Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx)
+    });
     let snapshot = buffer.read_with(cx, |buffer, _| buffer.snapshot());
 
     // point is at the start of an item
@@ -877,7 +884,8 @@ fn test_enclosing_bracket_ranges_where_brackets_are_not_outermost_children(cx: &
 fn test_range_for_syntax_ancestor(cx: &mut AppContext) {
     cx.add_model(|cx| {
         let text = "fn a() { b(|c| {}) }";
-        let buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
         let snapshot = buffer.snapshot();
 
         assert_eq!(
@@ -917,7 +925,8 @@ fn test_autoindent_with_soft_tabs(cx: &mut AppContext) {
 
     cx.add_model(|cx| {
         let text = "fn a() {}";
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
 
         buffer.edit([(8..8, "\n\n")], Some(AutoindentMode::EachLine), cx);
         assert_eq!(buffer.text(), "fn a() {\n    \n}");
@@ -959,7 +968,8 @@ fn test_autoindent_with_hard_tabs(cx: &mut AppContext) {
 
     cx.add_model(|cx| {
         let text = "fn a() {}";
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
 
         buffer.edit([(8..8, "\n\n")], Some(AutoindentMode::EachLine), cx);
         assert_eq!(buffer.text(), "fn a() {\n\t\n}");
@@ -1000,6 +1010,7 @@ fn test_autoindent_does_not_adjust_lines_with_unchanged_suggestion(cx: &mut AppC
     cx.add_model(|cx| {
         let mut buffer = Buffer::new(
             0,
+            cx.model_id() as u64,
             "
             fn a() {
             c;
@@ -1007,7 +1018,6 @@ fn test_autoindent_does_not_adjust_lines_with_unchanged_suggestion(cx: &mut AppC
             }
             "
             .unindent(),
-            cx,
         )
         .with_language(Arc::new(rust_lang()), cx);
 
@@ -1073,6 +1083,7 @@ fn test_autoindent_does_not_adjust_lines_with_unchanged_suggestion(cx: &mut AppC
     cx.add_model(|cx| {
         let mut buffer = Buffer::new(
             0,
+            cx.model_id() as u64,
             "
             fn a() {
                 b();
@@ -1080,7 +1091,6 @@ fn test_autoindent_does_not_adjust_lines_with_unchanged_suggestion(cx: &mut AppC
             "
             .replace("|", "") // marker to preserve trailing whitespace
             .unindent(),
-            cx,
         )
         .with_language(Arc::new(rust_lang()), cx);
 
@@ -1136,13 +1146,13 @@ fn test_autoindent_does_not_adjust_lines_within_newly_created_errors(cx: &mut Ap
     cx.add_model(|cx| {
         let mut buffer = Buffer::new(
             0,
+            cx.model_id() as u64,
             "
             fn a() {
                 i
             }
             "
             .unindent(),
-            cx,
         )
         .with_language(Arc::new(rust_lang()), cx);
 
@@ -1198,11 +1208,11 @@ fn test_autoindent_adjusts_lines_when_only_text_changes(cx: &mut AppContext) {
     cx.add_model(|cx| {
         let mut buffer = Buffer::new(
             0,
+            cx.model_id() as u64,
             "
             fn a() {}
             "
             .unindent(),
-            cx,
         )
         .with_language(Arc::new(rust_lang()), cx);
 
@@ -1254,7 +1264,8 @@ fn test_autoindent_with_edit_at_end_of_buffer(cx: &mut AppContext) {
 
     cx.add_model(|cx| {
         let text = "a\nb";
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
         buffer.edit(
             [(0..1, "\n"), (2..3, "\n")],
             Some(AutoindentMode::EachLine),
@@ -1280,7 +1291,8 @@ fn test_autoindent_multi_line_insertion(cx: &mut AppContext) {
         "
         .unindent();
 
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
         buffer.edit(
             [(Point::new(3, 0)..Point::new(3, 0), "e(\n    f()\n);\n")],
             Some(AutoindentMode::EachLine),
@@ -1317,7 +1329,8 @@ fn test_autoindent_block_mode(cx: &mut AppContext) {
             }
         "#
         .unindent();
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
 
         // When this text was copied, both of the quotation marks were at the same
         // indent level, but the indentation of the first line was not included in
@@ -1402,7 +1415,8 @@ fn test_autoindent_block_mode_without_original_indent_columns(cx: &mut AppContex
             }
         "#
         .unindent();
-        let mut buffer = Buffer::new(0, text, cx).with_language(Arc::new(rust_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(rust_lang()), cx);
 
         // The original indent columns are not known, so this text is
         // auto-indented in a block as if the first line was copied in
@@ -1481,7 +1495,7 @@ fn test_autoindent_language_without_indents_query(cx: &mut AppContext) {
         "
         .unindent();
 
-        let mut buffer = Buffer::new(0, text, cx).with_language(
+        let mut buffer = Buffer::new(0, cx.model_id() as u64, text).with_language(
             Arc::new(Language::new(
                 LanguageConfig {
                     name: "Markdown".into(),
@@ -1557,7 +1571,7 @@ fn test_autoindent_with_injected_languages(cx: &mut AppContext) {
             false,
         );
 
-        let mut buffer = Buffer::new(0, text, cx);
+        let mut buffer = Buffer::new(0, cx.model_id() as u64, text);
         buffer.set_language_registry(language_registry);
         buffer.set_language(Some(html_language), cx);
         buffer.edit(
@@ -1593,7 +1607,8 @@ fn test_autoindent_query_with_outdent_captures(cx: &mut AppContext) {
     });
 
     cx.add_model(|cx| {
-        let mut buffer = Buffer::new(0, "", cx).with_language(Arc::new(ruby_lang()), cx);
+        let mut buffer =
+            Buffer::new(0, cx.model_id() as u64, "").with_language(Arc::new(ruby_lang()), cx);
 
         let text = r#"
             class C
@@ -1683,7 +1698,8 @@ fn test_language_scope_at_with_javascript(cx: &mut AppContext) {
 
         let text = r#"a["b"] = <C d="e"></C>;"#;
 
-        let buffer = Buffer::new(0, text, cx).with_language(Arc::new(language), cx);
+        let buffer =
+            Buffer::new(0, cx.model_id() as u64, text).with_language(Arc::new(language), cx);
         let snapshot = buffer.snapshot();
 
         let config = snapshot.language_scope_at(0).unwrap();
@@ -1762,7 +1778,8 @@ fn test_language_scope_at_with_rust(cx: &mut AppContext) {
         "#
         .unindent();
 
-        let buffer = Buffer::new(0, text.clone(), cx).with_language(Arc::new(language), cx);
+        let buffer = Buffer::new(0, cx.model_id() as u64, text.clone())
+            .with_language(Arc::new(language), cx);
         let snapshot = buffer.snapshot();
 
         // By default, all brackets are enabled
@@ -1806,7 +1823,7 @@ fn test_language_scope_at_with_combined_injections(cx: &mut AppContext) {
         language_registry.add(Arc::new(html_lang()));
         language_registry.add(Arc::new(erb_lang()));
 
-        let mut buffer = Buffer::new(0, text, cx);
+        let mut buffer = Buffer::new(0, cx.model_id() as u64, text);
         buffer.set_language_registry(language_registry.clone());
         buffer.set_language(
             language_registry
@@ -1838,7 +1855,7 @@ fn test_serialization(cx: &mut gpui::AppContext) {
     let mut now = Instant::now();
 
     let buffer1 = cx.add_model(|cx| {
-        let mut buffer = Buffer::new(0, "abc", cx);
+        let mut buffer = Buffer::new(0, cx.model_id() as u64, "abc");
         buffer.edit([(3..3, "D")], None, cx);
 
         now += Duration::from_secs(1);
@@ -1893,7 +1910,7 @@ fn test_random_collaboration(cx: &mut AppContext, mut rng: StdRng) {
     let mut replica_ids = Vec::new();
     let mut buffers = Vec::new();
     let network = Rc::new(RefCell::new(Network::new(rng.clone())));
-    let base_buffer = cx.add_model(|cx| Buffer::new(0, base_text.as_str(), cx));
+    let base_buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, base_text.as_str()));
 
     for i in 0..rng.gen_range(min_peers..=max_peers) {
         let buffer = cx.add_model(|cx| {
@@ -2394,7 +2411,8 @@ fn assert_bracket_pairs(
 ) {
     let (expected_text, selection_ranges) = marked_text_ranges(selection_text, false);
     let buffer = cx.add_model(|cx| {
-        Buffer::new(0, expected_text.clone(), cx).with_language(Arc::new(language), cx)
+        Buffer::new(0, cx.model_id() as u64, expected_text.clone())
+            .with_language(Arc::new(language), cx)
     });
     let buffer = buffer.update(cx, |buffer, _cx| buffer.snapshot());
 

crates/language/src/language.rs

@@ -18,7 +18,7 @@ use futures::{
     FutureExt, TryFutureExt as _,
 };
 use gpui::{executor::Background, AppContext, AsyncAppContext, Task};
-use highlight_map::HighlightMap;
+pub use highlight_map::HighlightMap;
 use lazy_static::lazy_static;
 use lsp::{CodeActionKind, LanguageServerBinary};
 use parking_lot::{Mutex, RwLock};

crates/language/src/proto.rs

@@ -207,6 +207,7 @@ pub fn serialize_anchor(anchor: &Anchor) -> proto::Anchor {
     }
 }
 
+// This behavior is currently copied in the collab database, for snapshotting channel notes
 pub fn deserialize_operation(message: proto::Operation) -> Result<crate::Operation> {
     Ok(
         match message

crates/language/src/syntax_map.rs

@@ -310,7 +310,9 @@ impl SyntaxSnapshot {
             // Ignore edits that end before the start of this layer, and don't consider them
             // for any subsequent layers at this same depth.
             loop {
-                let Some((_, edit_range)) = edits.get(first_edit_ix_for_depth) else { continue 'outer };
+                let Some((_, edit_range)) = edits.get(first_edit_ix_for_depth) else {
+                    continue 'outer;
+                };
                 if edit_range.end.cmp(&layer.range.start, text).is_le() {
                     first_edit_ix_for_depth += 1;
                 } else {
@@ -391,7 +393,9 @@ impl SyntaxSnapshot {
                     .filter::<_, ()>(|summary| summary.contains_unknown_injections);
                 cursor.next(text);
                 while let Some(layer) = cursor.item() {
-                    let SyntaxLayerContent::Pending { language_name } = &layer.content else { unreachable!() };
+                    let SyntaxLayerContent::Pending { language_name } = &layer.content else {
+                        unreachable!()
+                    };
                     if registry
                         .language_for_name_or_extension(language_name)
                         .now_or_never()
@@ -533,7 +537,9 @@ impl SyntaxSnapshot {
 
             let content = match step.language {
                 ParseStepLanguage::Loaded { language } => {
-                    let Some(grammar) = language.grammar() else { continue };
+                    let Some(grammar) = language.grammar() else {
+                        continue;
+                    };
                     let tree;
                     let changed_ranges;
 

crates/language/src/syntax_map/syntax_map_tests.rs

@@ -932,8 +932,12 @@ fn check_interpolation(
         .zip(new_syntax_map.layers.iter())
     {
         assert_eq!(old_layer.range, new_layer.range);
-        let Some(old_tree) = old_layer.content.tree() else { continue };
-        let Some(new_tree) = new_layer.content.tree() else { continue };
+        let Some(old_tree) = old_layer.content.tree() else {
+            continue;
+        };
+        let Some(new_tree) = new_layer.content.tree() else {
+            continue;
+        };
         let old_start_byte = old_layer.range.start.to_offset(old_buffer);
         let new_start_byte = new_layer.range.start.to_offset(new_buffer);
         let old_start_point = old_layer.range.start.to_point(old_buffer).to_ts_point();

crates/language_tools/src/lsp_log.rs

@@ -176,7 +176,9 @@ impl LogStore {
                     cx.notify();
                     LanguageServerState {
                         rpc_state: None,
-                        log_buffer: cx.add_model(|cx| Buffer::new(0, "", cx)).clone(),
+                        log_buffer: cx
+                            .add_model(|cx| Buffer::new(0, cx.model_id() as u64, ""))
+                            .clone(),
                     }
                 })
                 .log_buffer
@@ -241,7 +243,7 @@ impl LogStore {
         let rpc_state = server_state.rpc_state.get_or_insert_with(|| {
             let io_tx = self.io_tx.clone();
             let language = project.read(cx).languages().language_for_name("JSON");
-            let buffer = cx.add_model(|cx| Buffer::new(0, "", cx));
+            let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, ""));
             cx.spawn_weak({
                 let buffer = buffer.clone();
                 |_, mut cx| async move {
@@ -327,7 +329,7 @@ impl LspLogView {
             .projects
             .get(&project.downgrade())
             .and_then(|project| project.servers.keys().copied().next());
-        let buffer = cx.add_model(|cx| Buffer::new(0, "", cx));
+        let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, ""));
         let mut this = Self {
             editor: Self::editor_for_buffer(project.clone(), buffer, cx),
             project,
@@ -549,7 +551,9 @@ impl View for LspLogToolbarItemView {
 
     fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
         let theme = theme::current(cx).clone();
-        let Some(log_view) = self.log_view.as_ref() else { return Empty::new().into_any() };
+        let Some(log_view) = self.log_view.as_ref() else {
+            return Empty::new().into_any();
+        };
         let log_view = log_view.read(cx);
         let menu_rows = log_view.menu_items(cx).unwrap_or_default();
 

crates/lsp/src/lsp.rs

@@ -77,7 +77,7 @@ pub enum Subscription {
 }
 
 #[derive(Serialize, Deserialize)]
-struct Request<'a, T> {
+pub struct Request<'a, T> {
     jsonrpc: &'static str,
     id: usize,
     method: &'a str,
@@ -435,7 +435,13 @@ impl LanguageServer {
                     }),
                     inlay_hint: Some(InlayHintClientCapabilities {
                         resolve_support: Some(InlayHintResolveClientCapabilities {
-                            properties: vec!["textEdits".to_string(), "tooltip".to_string()],
+                            properties: vec![
+                                "textEdits".to_string(),
+                                "tooltip".to_string(),
+                                "label.tooltip".to_string(),
+                                "label.location".to_string(),
+                                "label.command".to_string(),
+                            ],
                         }),
                         dynamic_registration: Some(false),
                     }),

crates/project/src/lsp_command.rs

@@ -1,21 +1,23 @@
 use crate::{
     DocumentHighlight, Hover, HoverBlock, HoverBlockKind, InlayHint, InlayHintLabel,
     InlayHintLabelPart, InlayHintLabelPartTooltip, InlayHintTooltip, Location, LocationLink,
-    MarkupContent, Project, ProjectTransaction,
+    MarkupContent, Project, ProjectTransaction, ResolveState,
 };
 use anyhow::{anyhow, Context, Result};
 use async_trait::async_trait;
 use client::proto::{self, PeerId};
 use fs::LineEnding;
+use futures::future;
 use gpui::{AppContext, AsyncAppContext, ModelHandle};
 use language::{
     language_settings::{language_settings, InlayHintKind},
     point_from_lsp, point_to_lsp,
     proto::{deserialize_anchor, deserialize_version, serialize_anchor, serialize_version},
-    range_from_lsp, range_to_lsp, Anchor, Bias, Buffer, CachedLspAdapter, CharKind, CodeAction,
-    Completion, OffsetRangeExt, PointUtf16, ToOffset, ToPointUtf16, Transaction, Unclipped,
+    range_from_lsp, range_to_lsp, Anchor, Bias, Buffer, BufferSnapshot, CachedLspAdapter, CharKind,
+    CodeAction, Completion, OffsetRangeExt, PointUtf16, ToOffset, ToPointUtf16, Transaction,
+    Unclipped,
 };
-use lsp::{DocumentHighlightKind, LanguageServer, LanguageServerId, ServerCapabilities};
+use lsp::{DocumentHighlightKind, LanguageServer, LanguageServerId, OneOf, ServerCapabilities};
 use std::{cmp::Reverse, ops::Range, path::Path, sync::Arc};
 
 pub fn lsp_formatting_options(tab_size: u32) -> lsp::FormattingOptions {
@@ -1431,7 +1433,7 @@ impl LspCommand for GetCompletions {
                 })
         });
 
-        Ok(futures::future::join_all(completions).await)
+        Ok(future::join_all(completions).await)
     }
 
     fn to_proto(&self, project_id: u64, buffer: &Buffer) -> proto::GetCompletions {
@@ -1499,7 +1501,7 @@ impl LspCommand for GetCompletions {
         let completions = message.completions.into_iter().map(|completion| {
             language::proto::deserialize_completion(completion, language.clone())
         });
-        futures::future::try_join_all(completions).await
+        future::try_join_all(completions).await
     }
 
     fn buffer_id_from_proto(message: &proto::GetCompletions) -> u64 {
@@ -1653,7 +1655,11 @@ impl LspCommand for OnTypeFormatting {
     type ProtoRequest = proto::OnTypeFormatting;
 
     fn check_capabilities(&self, server_capabilities: &lsp::ServerCapabilities) -> bool {
-        let Some(on_type_formatting_options) = &server_capabilities.document_on_type_formatting_provider else { return false };
+        let Some(on_type_formatting_options) =
+            &server_capabilities.document_on_type_formatting_provider
+        else {
+            return false;
+        };
         on_type_formatting_options
             .first_trigger_character
             .contains(&self.trigger)
@@ -1767,7 +1773,9 @@ impl LspCommand for OnTypeFormatting {
         _: ModelHandle<Buffer>,
         _: AsyncAppContext,
     ) -> Result<Option<Transaction>> {
-        let Some(transaction) = message.transaction else { return Ok(None) };
+        let Some(transaction) = message.transaction else {
+            return Ok(None);
+        };
         Ok(Some(language::proto::deserialize_transaction(transaction)?))
     }
 
@@ -1776,6 +1784,377 @@ impl LspCommand for OnTypeFormatting {
     }
 }
 
+impl InlayHints {
+    pub async fn lsp_to_project_hint(
+        lsp_hint: lsp::InlayHint,
+        buffer_handle: &ModelHandle<Buffer>,
+        server_id: LanguageServerId,
+        resolve_state: ResolveState,
+        force_no_type_left_padding: bool,
+        cx: &mut AsyncAppContext,
+    ) -> anyhow::Result<InlayHint> {
+        let kind = lsp_hint.kind.and_then(|kind| match kind {
+            lsp::InlayHintKind::TYPE => Some(InlayHintKind::Type),
+            lsp::InlayHintKind::PARAMETER => Some(InlayHintKind::Parameter),
+            _ => None,
+        });
+
+        let position = cx.update(|cx| {
+            let buffer = buffer_handle.read(cx);
+            let position = buffer.clip_point_utf16(point_from_lsp(lsp_hint.position), Bias::Left);
+            if kind == Some(InlayHintKind::Parameter) {
+                buffer.anchor_before(position)
+            } else {
+                buffer.anchor_after(position)
+            }
+        });
+        let label = Self::lsp_inlay_label_to_project(lsp_hint.label, server_id)
+            .await
+            .context("lsp to project inlay hint conversion")?;
+        let padding_left = if force_no_type_left_padding && kind == Some(InlayHintKind::Type) {
+            false
+        } else {
+            lsp_hint.padding_left.unwrap_or(false)
+        };
+
+        Ok(InlayHint {
+            position,
+            padding_left,
+            padding_right: lsp_hint.padding_right.unwrap_or(false),
+            label,
+            kind,
+            tooltip: lsp_hint.tooltip.map(|tooltip| match tooltip {
+                lsp::InlayHintTooltip::String(s) => InlayHintTooltip::String(s),
+                lsp::InlayHintTooltip::MarkupContent(markup_content) => {
+                    InlayHintTooltip::MarkupContent(MarkupContent {
+                        kind: match markup_content.kind {
+                            lsp::MarkupKind::PlainText => HoverBlockKind::PlainText,
+                            lsp::MarkupKind::Markdown => HoverBlockKind::Markdown,
+                        },
+                        value: markup_content.value,
+                    })
+                }
+            }),
+            resolve_state,
+        })
+    }
+
+    async fn lsp_inlay_label_to_project(
+        lsp_label: lsp::InlayHintLabel,
+        server_id: LanguageServerId,
+    ) -> anyhow::Result<InlayHintLabel> {
+        let label = match lsp_label {
+            lsp::InlayHintLabel::String(s) => InlayHintLabel::String(s),
+            lsp::InlayHintLabel::LabelParts(lsp_parts) => {
+                let mut parts = Vec::with_capacity(lsp_parts.len());
+                for lsp_part in lsp_parts {
+                    parts.push(InlayHintLabelPart {
+                        value: lsp_part.value,
+                        tooltip: lsp_part.tooltip.map(|tooltip| match tooltip {
+                            lsp::InlayHintLabelPartTooltip::String(s) => {
+                                InlayHintLabelPartTooltip::String(s)
+                            }
+                            lsp::InlayHintLabelPartTooltip::MarkupContent(markup_content) => {
+                                InlayHintLabelPartTooltip::MarkupContent(MarkupContent {
+                                    kind: match markup_content.kind {
+                                        lsp::MarkupKind::PlainText => HoverBlockKind::PlainText,
+                                        lsp::MarkupKind::Markdown => HoverBlockKind::Markdown,
+                                    },
+                                    value: markup_content.value,
+                                })
+                            }
+                        }),
+                        location: Some(server_id).zip(lsp_part.location),
+                    });
+                }
+                InlayHintLabel::LabelParts(parts)
+            }
+        };
+
+        Ok(label)
+    }
+
+    pub fn project_to_proto_hint(response_hint: InlayHint) -> proto::InlayHint {
+        let (state, lsp_resolve_state) = match response_hint.resolve_state {
+            ResolveState::Resolved => (0, None),
+            ResolveState::CanResolve(server_id, resolve_data) => (
+                1,
+                resolve_data
+                    .map(|json_data| {
+                        serde_json::to_string(&json_data)
+                            .expect("failed to serialize resolve json data")
+                    })
+                    .map(|value| proto::resolve_state::LspResolveState {
+                        server_id: server_id.0 as u64,
+                        value,
+                    }),
+            ),
+            ResolveState::Resolving => (2, None),
+        };
+        let resolve_state = Some(proto::ResolveState {
+            state,
+            lsp_resolve_state,
+        });
+        proto::InlayHint {
+            position: Some(language::proto::serialize_anchor(&response_hint.position)),
+            padding_left: response_hint.padding_left,
+            padding_right: response_hint.padding_right,
+            label: Some(proto::InlayHintLabel {
+                label: Some(match response_hint.label {
+                    InlayHintLabel::String(s) => proto::inlay_hint_label::Label::Value(s),
+                    InlayHintLabel::LabelParts(label_parts) => {
+                        proto::inlay_hint_label::Label::LabelParts(proto::InlayHintLabelParts {
+                            parts: label_parts.into_iter().map(|label_part| {
+                                let location_url = label_part.location.as_ref().map(|(_, location)| location.uri.to_string());
+                                let location_range_start = label_part.location.as_ref().map(|(_, location)| point_from_lsp(location.range.start).0).map(|point| proto::PointUtf16 { row: point.row, column: point.column });
+                                let location_range_end = label_part.location.as_ref().map(|(_, location)| point_from_lsp(location.range.end).0).map(|point| proto::PointUtf16 { row: point.row, column: point.column });
+                                proto::InlayHintLabelPart {
+                                value: label_part.value,
+                                tooltip: label_part.tooltip.map(|tooltip| {
+                                    let proto_tooltip = match tooltip {
+                                        InlayHintLabelPartTooltip::String(s) => proto::inlay_hint_label_part_tooltip::Content::Value(s),
+                                        InlayHintLabelPartTooltip::MarkupContent(markup_content) => proto::inlay_hint_label_part_tooltip::Content::MarkupContent(proto::MarkupContent {
+                                            is_markdown: markup_content.kind == HoverBlockKind::Markdown,
+                                            value: markup_content.value,
+                                        }),
+                                    };
+                                    proto::InlayHintLabelPartTooltip {content: Some(proto_tooltip)}
+                                }),
+                                location_url,
+                                location_range_start,
+                                location_range_end,
+                                language_server_id: label_part.location.as_ref().map(|(server_id, _)| server_id.0 as u64),
+                            }}).collect()
+                        })
+                    }
+                }),
+            }),
+            kind: response_hint.kind.map(|kind| kind.name().to_string()),
+            tooltip: response_hint.tooltip.map(|response_tooltip| {
+                let proto_tooltip = match response_tooltip {
+                    InlayHintTooltip::String(s) => proto::inlay_hint_tooltip::Content::Value(s),
+                    InlayHintTooltip::MarkupContent(markup_content) => {
+                        proto::inlay_hint_tooltip::Content::MarkupContent(proto::MarkupContent {
+                            is_markdown: markup_content.kind == HoverBlockKind::Markdown,
+                            value: markup_content.value,
+                        })
+                    }
+                };
+                proto::InlayHintTooltip {
+                    content: Some(proto_tooltip),
+                }
+            }),
+            resolve_state,
+        }
+    }
+
+    pub fn proto_to_project_hint(message_hint: proto::InlayHint) -> anyhow::Result<InlayHint> {
+        let resolve_state = message_hint.resolve_state.as_ref().unwrap_or_else(|| {
+            panic!("incorrect proto inlay hint message: no resolve state in hint {message_hint:?}",)
+        });
+        let resolve_state_data = resolve_state
+            .lsp_resolve_state.as_ref()
+            .map(|lsp_resolve_state| {
+                serde_json::from_str::<Option<lsp::LSPAny>>(&lsp_resolve_state.value)
+                    .with_context(|| format!("incorrect proto inlay hint message: non-json resolve state {lsp_resolve_state:?}"))
+                    .map(|state| (LanguageServerId(lsp_resolve_state.server_id as usize), state))
+            })
+            .transpose()?;
+        let resolve_state = match resolve_state.state {
+            0 => ResolveState::Resolved,
+            1 => {
+                let (server_id, lsp_resolve_state) = resolve_state_data.with_context(|| {
+                    format!(
+                        "No lsp resolve data for the hint that can be resolved: {message_hint:?}"
+                    )
+                })?;
+                ResolveState::CanResolve(server_id, lsp_resolve_state)
+            }
+            2 => ResolveState::Resolving,
+            invalid => {
+                anyhow::bail!("Unexpected resolve state {invalid} for hint {message_hint:?}")
+            }
+        };
+        Ok(InlayHint {
+            position: message_hint
+                .position
+                .and_then(language::proto::deserialize_anchor)
+                .context("invalid position")?,
+            label: match message_hint
+                .label
+                .and_then(|label| label.label)
+                .context("missing label")?
+            {
+                proto::inlay_hint_label::Label::Value(s) => InlayHintLabel::String(s),
+                proto::inlay_hint_label::Label::LabelParts(parts) => {
+                    let mut label_parts = Vec::new();
+                    for part in parts.parts {
+                        label_parts.push(InlayHintLabelPart {
+                            value: part.value,
+                            tooltip: part.tooltip.map(|tooltip| match tooltip.content {
+                                Some(proto::inlay_hint_label_part_tooltip::Content::Value(s)) => {
+                                    InlayHintLabelPartTooltip::String(s)
+                                }
+                                Some(
+                                    proto::inlay_hint_label_part_tooltip::Content::MarkupContent(
+                                        markup_content,
+                                    ),
+                                ) => InlayHintLabelPartTooltip::MarkupContent(MarkupContent {
+                                    kind: if markup_content.is_markdown {
+                                        HoverBlockKind::Markdown
+                                    } else {
+                                        HoverBlockKind::PlainText
+                                    },
+                                    value: markup_content.value,
+                                }),
+                                None => InlayHintLabelPartTooltip::String(String::new()),
+                            }),
+                            location: {
+                                match part
+                                    .location_url
+                                    .zip(
+                                        part.location_range_start.and_then(|start| {
+                                            Some(start..part.location_range_end?)
+                                        }),
+                                    )
+                                    .zip(part.language_server_id)
+                                {
+                                    Some(((uri, range), server_id)) => Some((
+                                        LanguageServerId(server_id as usize),
+                                        lsp::Location {
+                                            uri: lsp::Url::parse(&uri)
+                                                .context("invalid uri in hint part {part:?}")?,
+                                            range: lsp::Range::new(
+                                                point_to_lsp(PointUtf16::new(
+                                                    range.start.row,
+                                                    range.start.column,
+                                                )),
+                                                point_to_lsp(PointUtf16::new(
+                                                    range.end.row,
+                                                    range.end.column,
+                                                )),
+                                            ),
+                                        },
+                                    )),
+                                    None => None,
+                                }
+                            },
+                        });
+                    }
+
+                    InlayHintLabel::LabelParts(label_parts)
+                }
+            },
+            padding_left: message_hint.padding_left,
+            padding_right: message_hint.padding_right,
+            kind: message_hint
+                .kind
+                .as_deref()
+                .and_then(InlayHintKind::from_name),
+            tooltip: message_hint.tooltip.and_then(|tooltip| {
+                Some(match tooltip.content? {
+                    proto::inlay_hint_tooltip::Content::Value(s) => InlayHintTooltip::String(s),
+                    proto::inlay_hint_tooltip::Content::MarkupContent(markup_content) => {
+                        InlayHintTooltip::MarkupContent(MarkupContent {
+                            kind: if markup_content.is_markdown {
+                                HoverBlockKind::Markdown
+                            } else {
+                                HoverBlockKind::PlainText
+                            },
+                            value: markup_content.value,
+                        })
+                    }
+                })
+            }),
+            resolve_state,
+        })
+    }
+
+    pub fn project_to_lsp_hint(hint: InlayHint, snapshot: &BufferSnapshot) -> lsp::InlayHint {
+        lsp::InlayHint {
+            position: point_to_lsp(hint.position.to_point_utf16(snapshot)),
+            kind: hint.kind.map(|kind| match kind {
+                InlayHintKind::Type => lsp::InlayHintKind::TYPE,
+                InlayHintKind::Parameter => lsp::InlayHintKind::PARAMETER,
+            }),
+            text_edits: None,
+            tooltip: hint.tooltip.and_then(|tooltip| {
+                Some(match tooltip {
+                    InlayHintTooltip::String(s) => lsp::InlayHintTooltip::String(s),
+                    InlayHintTooltip::MarkupContent(markup_content) => {
+                        lsp::InlayHintTooltip::MarkupContent(lsp::MarkupContent {
+                            kind: match markup_content.kind {
+                                HoverBlockKind::PlainText => lsp::MarkupKind::PlainText,
+                                HoverBlockKind::Markdown => lsp::MarkupKind::Markdown,
+                                HoverBlockKind::Code { .. } => return None,
+                            },
+                            value: markup_content.value,
+                        })
+                    }
+                })
+            }),
+            label: match hint.label {
+                InlayHintLabel::String(s) => lsp::InlayHintLabel::String(s),
+                InlayHintLabel::LabelParts(label_parts) => lsp::InlayHintLabel::LabelParts(
+                    label_parts
+                        .into_iter()
+                        .map(|part| lsp::InlayHintLabelPart {
+                            value: part.value,
+                            tooltip: part.tooltip.and_then(|tooltip| {
+                                Some(match tooltip {
+                                    InlayHintLabelPartTooltip::String(s) => {
+                                        lsp::InlayHintLabelPartTooltip::String(s)
+                                    }
+                                    InlayHintLabelPartTooltip::MarkupContent(markup_content) => {
+                                        lsp::InlayHintLabelPartTooltip::MarkupContent(
+                                            lsp::MarkupContent {
+                                                kind: match markup_content.kind {
+                                                    HoverBlockKind::PlainText => {
+                                                        lsp::MarkupKind::PlainText
+                                                    }
+                                                    HoverBlockKind::Markdown => {
+                                                        lsp::MarkupKind::Markdown
+                                                    }
+                                                    HoverBlockKind::Code { .. } => return None,
+                                                },
+                                                value: markup_content.value,
+                                            },
+                                        )
+                                    }
+                                })
+                            }),
+                            location: part.location.map(|(_, location)| location),
+                            command: None,
+                        })
+                        .collect(),
+                ),
+            },
+            padding_left: Some(hint.padding_left),
+            padding_right: Some(hint.padding_right),
+            data: match hint.resolve_state {
+                ResolveState::CanResolve(_, data) => data,
+                ResolveState::Resolving | ResolveState::Resolved => None,
+            },
+        }
+    }
+
+    pub fn can_resolve_inlays(capabilities: &ServerCapabilities) -> bool {
+        capabilities
+            .inlay_hint_provider
+            .as_ref()
+            .and_then(|options| match options {
+                OneOf::Left(_is_supported) => None,
+                OneOf::Right(capabilities) => match capabilities {
+                    lsp::InlayHintServerCapabilities::Options(o) => o.resolve_provider,
+                    lsp::InlayHintServerCapabilities::RegistrationOptions(o) => {
+                        o.inlay_hint_options.resolve_provider
+                    }
+                },
+            })
+            .unwrap_or(false)
+    }
+}
+
 #[async_trait(?Send)]
 impl LspCommand for InlayHints {
     type Response = Vec<InlayHint>;
@@ -1783,7 +2162,9 @@ impl LspCommand for InlayHints {
     type ProtoRequest = proto::InlayHints;
 
     fn check_capabilities(&self, server_capabilities: &lsp::ServerCapabilities) -> bool {
-        let Some(inlay_hint_provider) = &server_capabilities.inlay_hint_provider else { return false };
+        let Some(inlay_hint_provider) = &server_capabilities.inlay_hint_provider else {
+            return false;
+        };
         match inlay_hint_provider {
             lsp::OneOf::Left(enabled) => *enabled,
             lsp::OneOf::Right(inlay_hint_capabilities) => match inlay_hint_capabilities {
@@ -1816,8 +2197,9 @@ impl LspCommand for InlayHints {
         buffer: ModelHandle<Buffer>,
         server_id: LanguageServerId,
         mut cx: AsyncAppContext,
-    ) -> Result<Vec<InlayHint>> {
-        let (lsp_adapter, _) = language_server_for_buffer(&project, &buffer, server_id, &mut cx)?;
+    ) -> anyhow::Result<Vec<InlayHint>> {
+        let (lsp_adapter, lsp_server) =
+            language_server_for_buffer(&project, &buffer, server_id, &mut cx)?;
         // `typescript-language-server` adds padding to the left for type hints, turning
         // `const foo: boolean` into `const foo : boolean` which looks odd.
         // `rust-analyzer` does not have the padding for this case, and we have to accomodate both.
@@ -1827,93 +2209,32 @@ impl LspCommand for InlayHints {
         // Hence let's use a heuristic first to handle the most awkward case and look for more.
         let force_no_type_left_padding =
             lsp_adapter.name.0.as_ref() == "typescript-language-server";
-        cx.read(|cx| {
-            let origin_buffer = buffer.read(cx);
-            Ok(message
-                .unwrap_or_default()
-                .into_iter()
-                .map(|lsp_hint| {
-                    let kind = lsp_hint.kind.and_then(|kind| match kind {
-                        lsp::InlayHintKind::TYPE => Some(InlayHintKind::Type),
-                        lsp::InlayHintKind::PARAMETER => Some(InlayHintKind::Parameter),
-                        _ => None,
-                    });
-                    let position = origin_buffer
-                        .clip_point_utf16(point_from_lsp(lsp_hint.position), Bias::Left);
-                    let padding_left =
-                        if force_no_type_left_padding && kind == Some(InlayHintKind::Type) {
-                            false
+
+        let hints = message.unwrap_or_default().into_iter().map(|lsp_hint| {
+            let resolve_state = if InlayHints::can_resolve_inlays(lsp_server.capabilities()) {
+                ResolveState::CanResolve(lsp_server.server_id(), lsp_hint.data.clone())
             } else {
-                            lsp_hint.padding_left.unwrap_or(false)
+                ResolveState::Resolved
             };
-                    InlayHint {
-                        buffer_id: origin_buffer.remote_id(),
-                        position: if kind == Some(InlayHintKind::Parameter) {
-                            origin_buffer.anchor_before(position)
-                        } else {
-                            origin_buffer.anchor_after(position)
-                        },
-                        padding_left,
-                        padding_right: lsp_hint.padding_right.unwrap_or(false),
-                        label: match lsp_hint.label {
-                            lsp::InlayHintLabel::String(s) => InlayHintLabel::String(s),
-                            lsp::InlayHintLabel::LabelParts(lsp_parts) => {
-                                InlayHintLabel::LabelParts(
-                                    lsp_parts
-                                        .into_iter()
-                                        .map(|label_part| InlayHintLabelPart {
-                                            value: label_part.value,
-                                            tooltip: label_part.tooltip.map(
-                                                |tooltip| {
-                                                    match tooltip {
-                                        lsp::InlayHintLabelPartTooltip::String(s) => {
-                                            InlayHintLabelPartTooltip::String(s)
-                                        }
-                                        lsp::InlayHintLabelPartTooltip::MarkupContent(
-                                            markup_content,
-                                        ) => InlayHintLabelPartTooltip::MarkupContent(
-                                            MarkupContent {
-                                                kind: format!("{:?}", markup_content.kind),
-                                                value: markup_content.value,
-                                            },
-                                        ),
-                                    }
-                                                },
-                                            ),
-                                            location: label_part.location.map(|lsp_location| {
-                                                let target_start = origin_buffer.clip_point_utf16(
-                                                    point_from_lsp(lsp_location.range.start),
-                                                    Bias::Left,
-                                                );
-                                                let target_end = origin_buffer.clip_point_utf16(
-                                                    point_from_lsp(lsp_location.range.end),
-                                                    Bias::Left,
-                                                );
-                                                Location {
-                                                    buffer: buffer.clone(),
-                                                    range: origin_buffer.anchor_after(target_start)
-                                                        ..origin_buffer.anchor_before(target_end),
-                                                }
-                                            }),
-                                        })
-                                        .collect(),
+
+            let buffer = buffer.clone();
+            cx.spawn(|mut cx| async move {
+                InlayHints::lsp_to_project_hint(
+                    lsp_hint,
+                    &buffer,
+                    server_id,
+                    resolve_state,
+                    force_no_type_left_padding,
+                    &mut cx,
                 )
-                            }
-                        },
-                        kind,
-                        tooltip: lsp_hint.tooltip.map(|tooltip| match tooltip {
-                            lsp::InlayHintTooltip::String(s) => InlayHintTooltip::String(s),
-                            lsp::InlayHintTooltip::MarkupContent(markup_content) => {
-                                InlayHintTooltip::MarkupContent(MarkupContent {
-                                    kind: format!("{:?}", markup_content.kind),
-                                    value: markup_content.value,
-                                })
-                            }
-                        }),
-                    }
-                })
-                .collect())
+                .await
             })
+        });
+        future::join_all(hints)
+            .await
+            .into_iter()
+            .collect::<anyhow::Result<_>>()
+            .context("lsp to project inlay hints conversion")
     }
 
     fn to_proto(&self, project_id: u64, buffer: &Buffer) -> proto::InlayHints {
@@ -1959,23 +2280,7 @@ impl LspCommand for InlayHints {
         proto::InlayHintsResponse {
             hints: response
                 .into_iter()
-                .map(|response_hint| proto::InlayHint {
-                    position: Some(language::proto::serialize_anchor(&response_hint.position)),
-                    padding_left: response_hint.padding_left,
-                    padding_right: response_hint.padding_right,
-                    kind: response_hint.kind.map(|kind| kind.name().to_string()),
-                    // Do not pass extra data such as tooltips to clients: host can put tooltip data from the cache during resolution.
-                    tooltip: None,
-                    // Similarly, do not pass label parts to clients: host can return a detailed list during resolution.
-                    label: Some(proto::InlayHintLabel {
-                        label: Some(proto::inlay_hint_label::Label::Value(
-                            match response_hint.label {
-                                InlayHintLabel::String(s) => s,
-                                InlayHintLabel::LabelParts(_) => response_hint.text(),
-                            },
-                        )),
-                    }),
-                })
+                .map(|response_hint| InlayHints::project_to_proto_hint(response_hint))
                 .collect(),
             version: serialize_version(buffer_version),
         }
@@ -1984,10 +2289,10 @@ impl LspCommand for InlayHints {
     async fn response_from_proto(
         self,
         message: proto::InlayHintsResponse,
-        project: ModelHandle<Project>,
+        _: ModelHandle<Project>,
         buffer: ModelHandle<Buffer>,
         mut cx: AsyncAppContext,
-    ) -> Result<Vec<InlayHint>> {
+    ) -> anyhow::Result<Vec<InlayHint>> {
         buffer
             .update(&mut cx, |buffer, _| {
                 buffer.wait_for_version(deserialize_version(&message.version))
@@ -1996,82 +2301,7 @@ impl LspCommand for InlayHints {
 
         let mut hints = Vec::new();
         for message_hint in message.hints {
-            let buffer_id = message_hint
-                .position
-                .as_ref()
-                .and_then(|location| location.buffer_id)
-                .context("missing buffer id")?;
-            let hint = InlayHint {
-                buffer_id,
-                position: message_hint
-                    .position
-                    .and_then(language::proto::deserialize_anchor)
-                    .context("invalid position")?,
-                label: match message_hint
-                    .label
-                    .and_then(|label| label.label)
-                    .context("missing label")?
-                {
-                    proto::inlay_hint_label::Label::Value(s) => InlayHintLabel::String(s),
-                    proto::inlay_hint_label::Label::LabelParts(parts) => {
-                        let mut label_parts = Vec::new();
-                        for part in parts.parts {
-                            label_parts.push(InlayHintLabelPart {
-                                value: part.value,
-                                tooltip: part.tooltip.map(|tooltip| match tooltip.content {
-                                    Some(proto::inlay_hint_label_part_tooltip::Content::Value(s)) => InlayHintLabelPartTooltip::String(s),
-                                    Some(proto::inlay_hint_label_part_tooltip::Content::MarkupContent(markup_content)) => InlayHintLabelPartTooltip::MarkupContent(MarkupContent {
-                                        kind: markup_content.kind,
-                                        value: markup_content.value,
-                                    }),
-                                    None => InlayHintLabelPartTooltip::String(String::new()),
-                                }),
-                                location: match part.location {
-                                    Some(location) => {
-                                        let target_buffer = project
-                                            .update(&mut cx, |this, cx| {
-                                                this.wait_for_remote_buffer(location.buffer_id, cx)
-                                            })
-                                            .await?;
-                                        Some(Location {
-                                        range: location
-                                            .start
-                                            .and_then(language::proto::deserialize_anchor)
-                                            .context("invalid start")?
-                                            ..location
-                                                .end
-                                                .and_then(language::proto::deserialize_anchor)
-                                                .context("invalid end")?,
-                                        buffer: target_buffer,
-                                    })},
-                                    None => None,
-                                },
-                            });
-                        }
-
-                        InlayHintLabel::LabelParts(label_parts)
-                    }
-                },
-                padding_left: message_hint.padding_left,
-                padding_right: message_hint.padding_right,
-                kind: message_hint
-                    .kind
-                    .as_deref()
-                    .and_then(InlayHintKind::from_name),
-                tooltip: message_hint.tooltip.and_then(|tooltip| {
-                    Some(match tooltip.content? {
-                        proto::inlay_hint_tooltip::Content::Value(s) => InlayHintTooltip::String(s),
-                        proto::inlay_hint_tooltip::Content::MarkupContent(markup_content) => {
-                            InlayHintTooltip::MarkupContent(MarkupContent {
-                                kind: markup_content.kind,
-                                value: markup_content.value,
-                            })
-                        }
-                    })
-                }),
-            };
-
-            hints.push(hint);
+            hints.push(InlayHints::proto_to_project_hint(message_hint)?);
         }
 
         Ok(hints)

crates/project/src/project.rs

@@ -11,7 +11,7 @@ mod project_tests;
 mod worktree_tests;
 
 use anyhow::{anyhow, Context, Result};
-use client::{proto, Client, TypedEnvelope, UserStore};
+use client::{proto, Client, TypedEnvelope, UserId, UserStore};
 use clock::ReplicaId;
 use collections::{hash_map, BTreeMap, HashMap, HashSet};
 use copilot::Copilot;
@@ -26,8 +26,8 @@ use futures::{
 };
 use globset::{Glob, GlobSet, GlobSetBuilder};
 use gpui::{
-    AnyModelHandle, AppContext, AsyncAppContext, BorrowAppContext, Entity, ModelContext,
-    ModelHandle, Task, WeakModelHandle,
+    executor::Background, AnyModelHandle, AppContext, AsyncAppContext, BorrowAppContext, Entity,
+    ModelContext, ModelHandle, Task, WeakModelHandle,
 };
 use itertools::Itertools;
 use language::{
@@ -37,11 +37,11 @@ use language::{
         deserialize_anchor, deserialize_fingerprint, deserialize_line_ending, deserialize_version,
         serialize_anchor, serialize_version,
     },
-    range_from_lsp, range_to_lsp, Bias, Buffer, CachedLspAdapter, CodeAction, CodeLabel,
-    Completion, Diagnostic, DiagnosticEntry, DiagnosticSet, Diff, Event as BufferEvent, File as _,
-    Language, LanguageRegistry, LanguageServerName, LocalFile, LspAdapterDelegate, OffsetRangeExt,
-    Operation, Patch, PendingLanguageServer, PointUtf16, TextBufferSnapshot, ToOffset,
-    ToPointUtf16, Transaction, Unclipped,
+    range_from_lsp, range_to_lsp, Bias, Buffer, BufferSnapshot, CachedLspAdapter, CodeAction,
+    CodeLabel, Completion, Diagnostic, DiagnosticEntry, DiagnosticSet, Diff, Event as BufferEvent,
+    File as _, Language, LanguageRegistry, LanguageServerName, LocalFile, LspAdapterDelegate,
+    OffsetRangeExt, Operation, Patch, PendingLanguageServer, PointUtf16, TextBufferSnapshot,
+    ToOffset, ToPointUtf16, Transaction, Unclipped,
 };
 use log::error;
 use lsp::{
@@ -57,8 +57,8 @@ use serde::Serialize;
 use settings::SettingsStore;
 use sha2::{Digest, Sha256};
 use similar::{ChangeTag, TextDiff};
+use smol::channel::{Receiver, Sender};
 use std::{
-    cell::RefCell,
     cmp::{self, Ordering},
     convert::TryInto,
     hash::Hash,
@@ -67,7 +67,6 @@ use std::{
     ops::Range,
     path::{self, Component, Path, PathBuf},
     process::Stdio,
-    rc::Rc,
     str,
     sync::{
         atomic::{AtomicUsize, Ordering::SeqCst},
@@ -250,6 +249,7 @@ enum ProjectClientState {
 pub struct Collaborator {
     pub peer_id: proto::PeerId,
     pub replica_id: ReplicaId,
+    pub user_id: UserId,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -281,6 +281,7 @@ pub enum Event {
         old_peer_id: proto::PeerId,
         new_peer_id: proto::PeerId,
     },
+    CollaboratorJoined(proto::PeerId),
     CollaboratorLeft(proto::PeerId),
     RefreshInlayHints,
 }
@@ -331,15 +332,22 @@ pub struct Location {
     pub range: Range<language::Anchor>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct InlayHint {
-    pub buffer_id: u64,
     pub position: language::Anchor,
     pub label: InlayHintLabel,
     pub kind: Option<InlayHintKind>,
     pub padding_left: bool,
     pub padding_right: bool,
     pub tooltip: Option<InlayHintTooltip>,
+    pub resolve_state: ResolveState,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ResolveState {
+    Resolved,
+    CanResolve(LanguageServerId, Option<lsp::LSPAny>),
+    Resolving,
 }
 
 impl InlayHint {
@@ -351,34 +359,34 @@ impl InlayHint {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum InlayHintLabel {
     String(String),
     LabelParts(Vec<InlayHintLabelPart>),
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct InlayHintLabelPart {
     pub value: String,
     pub tooltip: Option<InlayHintLabelPartTooltip>,
-    pub location: Option<Location>,
+    pub location: Option<(LanguageServerId, lsp::Location)>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum InlayHintTooltip {
     String(String),
     MarkupContent(MarkupContent),
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum InlayHintLabelPartTooltip {
     String(String),
     MarkupContent(MarkupContent),
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct MarkupContent {
-    pub kind: String,
+    pub kind: HoverBlockKind,
     pub value: String,
 }
 
@@ -412,7 +420,7 @@ pub struct HoverBlock {
     pub kind: HoverBlockKind,
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum HoverBlockKind {
     PlainText,
     Markdown,
@@ -516,6 +524,28 @@ impl FormatTrigger {
         }
     }
 }
+#[derive(Clone, Debug, PartialEq)]
+enum SearchMatchCandidate {
+    OpenBuffer {
+        buffer: ModelHandle<Buffer>,
+        // This might be an unnamed file without representation on filesystem
+        path: Option<Arc<Path>>,
+    },
+    Path {
+        worktree_id: WorktreeId,
+        path: Arc<Path>,
+    },
+}
+
+type SearchMatchCandidateIndex = usize;
+impl SearchMatchCandidate {
+    fn path(&self) -> Option<Arc<Path>> {
+        match self {
+            SearchMatchCandidate::OpenBuffer { path, .. } => path.clone(),
+            SearchMatchCandidate::Path { path, .. } => Some(path.clone()),
+        }
+    }
+}
 
 impl Project {
     pub fn init_settings(cx: &mut AppContext) {
@@ -549,6 +579,7 @@ impl Project {
         client.add_model_request_handler(Self::handle_apply_code_action);
         client.add_model_request_handler(Self::handle_on_type_formatting);
         client.add_model_request_handler(Self::handle_inlay_hints);
+        client.add_model_request_handler(Self::handle_resolve_inlay_hint);
         client.add_model_request_handler(Self::handle_refresh_inlay_hints);
         client.add_model_request_handler(Self::handle_reload_buffers);
         client.add_model_request_handler(Self::handle_synchronize_buffers);
@@ -1537,9 +1568,9 @@ impl Project {
         if self.is_remote() {
             return Err(anyhow!("creating buffers as a guest is not supported yet"));
         }
-
+        let id = post_inc(&mut self.next_buffer_id);
         let buffer = cx.add_model(|cx| {
-            Buffer::new(self.replica_id(), text, cx)
+            Buffer::new(self.replica_id(), id, text)
                 .with_language(language.unwrap_or_else(|| language::PLAIN_TEXT.clone()), cx)
         });
         self.register_buffer(&buffer, cx)?;
@@ -1677,7 +1708,7 @@ impl Project {
     }
 
     /// LanguageServerName is owned, because it is inserted into a map
-    fn open_local_buffer_via_lsp(
+    pub fn open_local_buffer_via_lsp(
         &mut self,
         abs_path: lsp::Url,
         language_server_id: LanguageServerId,
@@ -4967,7 +4998,7 @@ impl Project {
         buffer_handle: ModelHandle<Buffer>,
         range: Range<T>,
         cx: &mut ModelContext<Self>,
-    ) -> Task<Result<Vec<InlayHint>>> {
+    ) -> Task<anyhow::Result<Vec<InlayHint>>> {
         let buffer = buffer_handle.read(cx);
         let range = buffer.anchor_before(range.start)..buffer.anchor_before(range.end);
         let range_start = range.start;
@@ -5017,192 +5048,79 @@ impl Project {
         }
     }
 
+    pub fn resolve_inlay_hint(
+        &self,
+        hint: InlayHint,
+        buffer_handle: ModelHandle<Buffer>,
+        server_id: LanguageServerId,
+        cx: &mut ModelContext<Self>,
+    ) -> Task<anyhow::Result<InlayHint>> {
+        if self.is_local() {
+            let buffer = buffer_handle.read(cx);
+            let (_, lang_server) = if let Some((adapter, server)) =
+                self.language_server_for_buffer(buffer, server_id, cx)
+            {
+                (adapter.clone(), server.clone())
+            } else {
+                return Task::ready(Ok(hint));
+            };
+            if !InlayHints::can_resolve_inlays(lang_server.capabilities()) {
+                return Task::ready(Ok(hint));
+            }
+
+            let buffer_snapshot = buffer.snapshot();
+            cx.spawn(|_, mut cx| async move {
+                let resolve_task = lang_server.request::<lsp::request::InlayHintResolveRequest>(
+                    InlayHints::project_to_lsp_hint(hint, &buffer_snapshot),
+                );
+                let resolved_hint = resolve_task
+                    .await
+                    .context("inlay hint resolve LSP request")?;
+                let resolved_hint = InlayHints::lsp_to_project_hint(
+                    resolved_hint,
+                    &buffer_handle,
+                    server_id,
+                    ResolveState::Resolved,
+                    false,
+                    &mut cx,
+                )
+                .await?;
+                Ok(resolved_hint)
+            })
+        } else if let Some(project_id) = self.remote_id() {
+            let client = self.client.clone();
+            let request = proto::ResolveInlayHint {
+                project_id,
+                buffer_id: buffer_handle.read(cx).remote_id(),
+                language_server_id: server_id.0 as u64,
+                hint: Some(InlayHints::project_to_proto_hint(hint.clone())),
+            };
+            cx.spawn(|_, _| async move {
+                let response = client
+                    .request(request)
+                    .await
+                    .context("inlay hints proto request")?;
+                match response.hint {
+                    Some(resolved_hint) => InlayHints::proto_to_project_hint(resolved_hint)
+                        .context("inlay hints proto resolve response conversion"),
+                    None => Ok(hint),
+                }
+            })
+        } else {
+            Task::ready(Err(anyhow!("project does not have a remote id")))
+        }
+    }
+
     #[allow(clippy::type_complexity)]
     pub fn search(
         &self,
         query: SearchQuery,
         cx: &mut ModelContext<Self>,
-    ) -> Task<Result<HashMap<ModelHandle<Buffer>, Vec<Range<Anchor>>>>> {
+    ) -> Receiver<(ModelHandle<Buffer>, Vec<Range<Anchor>>)> {
         if self.is_local() {
-            let snapshots = self
-                .visible_worktrees(cx)
-                .filter_map(|tree| {
-                    let tree = tree.read(cx).as_local()?;
-                    Some(tree.snapshot())
-                })
-                .collect::<Vec<_>>();
-
-            let background = cx.background().clone();
-            let path_count: usize = snapshots.iter().map(|s| s.visible_file_count()).sum();
-            if path_count == 0 {
-                return Task::ready(Ok(Default::default()));
-            }
-            let workers = background.num_cpus().min(path_count);
-            let (matching_paths_tx, mut matching_paths_rx) = smol::channel::bounded(1024);
-            cx.background()
-                .spawn({
-                    let fs = self.fs.clone();
-                    let background = cx.background().clone();
-                    let query = query.clone();
-                    async move {
-                        let fs = &fs;
-                        let query = &query;
-                        let matching_paths_tx = &matching_paths_tx;
-                        let paths_per_worker = (path_count + workers - 1) / workers;
-                        let snapshots = &snapshots;
-                        background
-                            .scoped(|scope| {
-                                for worker_ix in 0..workers {
-                                    let worker_start_ix = worker_ix * paths_per_worker;
-                                    let worker_end_ix = worker_start_ix + paths_per_worker;
-                                    scope.spawn(async move {
-                                        let mut snapshot_start_ix = 0;
-                                        let mut abs_path = PathBuf::new();
-                                        for snapshot in snapshots {
-                                            let snapshot_end_ix =
-                                                snapshot_start_ix + snapshot.visible_file_count();
-                                            if worker_end_ix <= snapshot_start_ix {
-                                                break;
-                                            } else if worker_start_ix > snapshot_end_ix {
-                                                snapshot_start_ix = snapshot_end_ix;
-                                                continue;
-                                            } else {
-                                                let start_in_snapshot = worker_start_ix
-                                                    .saturating_sub(snapshot_start_ix);
-                                                let end_in_snapshot =
-                                                    cmp::min(worker_end_ix, snapshot_end_ix)
-                                                        - snapshot_start_ix;
-
-                                                for entry in snapshot
-                                                    .files(false, start_in_snapshot)
-                                                    .take(end_in_snapshot - start_in_snapshot)
-                                                {
-                                                    if matching_paths_tx.is_closed() {
-                                                        break;
-                                                    }
-                                                    let matches = if query
-                                                        .file_matches(Some(&entry.path))
-                                                    {
-                                                        abs_path.clear();
-                                                        abs_path.push(&snapshot.abs_path());
-                                                        abs_path.push(&entry.path);
-                                                        if let Some(file) =
-                                                            fs.open_sync(&abs_path).await.log_err()
-                                                        {
-                                                            query.detect(file).unwrap_or(false)
-                                                        } else {
-                                                            false
-                                                        }
-                                                    } else {
-                                                        false
-                                                    };
-
-                                                    if matches {
-                                                        let project_path =
-                                                            (snapshot.id(), entry.path.clone());
-                                                        if matching_paths_tx
-                                                            .send(project_path)
-                                                            .await
-                                                            .is_err()
-                                                        {
-                                                            break;
-                                                        }
-                                                    }
-                                                }
-
-                                                snapshot_start_ix = snapshot_end_ix;
-                                            }
-                                        }
-                                    });
-                                }
-                            })
-                            .await;
-                    }
-                })
-                .detach();
-
-            let (buffers_tx, buffers_rx) = smol::channel::bounded(1024);
-            let open_buffers = self
-                .opened_buffers
-                .values()
-                .filter_map(|b| b.upgrade(cx))
-                .collect::<HashSet<_>>();
-            cx.spawn(|this, cx| async move {
-                for buffer in &open_buffers {
-                    let snapshot = buffer.read_with(&cx, |buffer, _| buffer.snapshot());
-                    buffers_tx.send((buffer.clone(), snapshot)).await?;
-                }
-
-                let open_buffers = Rc::new(RefCell::new(open_buffers));
-                while let Some(project_path) = matching_paths_rx.next().await {
-                    if buffers_tx.is_closed() {
-                        break;
-                    }
-
-                    let this = this.clone();
-                    let open_buffers = open_buffers.clone();
-                    let buffers_tx = buffers_tx.clone();
-                    cx.spawn(|mut cx| async move {
-                        if let Some(buffer) = this
-                            .update(&mut cx, |this, cx| this.open_buffer(project_path, cx))
-                            .await
-                            .log_err()
-                        {
-                            if open_buffers.borrow_mut().insert(buffer.clone()) {
-                                let snapshot = buffer.read_with(&cx, |buffer, _| buffer.snapshot());
-                                buffers_tx.send((buffer, snapshot)).await?;
-                            }
-                        }
-
-                        Ok::<_, anyhow::Error>(())
-                    })
-                    .detach();
-                }
-
-                Ok::<_, anyhow::Error>(())
-            })
-            .detach_and_log_err(cx);
-
-            let background = cx.background().clone();
-            cx.background().spawn(async move {
-                let query = &query;
-                let mut matched_buffers = Vec::new();
-                for _ in 0..workers {
-                    matched_buffers.push(HashMap::default());
-                }
-                background
-                    .scoped(|scope| {
-                        for worker_matched_buffers in matched_buffers.iter_mut() {
-                            let mut buffers_rx = buffers_rx.clone();
-                            scope.spawn(async move {
-                                while let Some((buffer, snapshot)) = buffers_rx.next().await {
-                                    let buffer_matches = if query.file_matches(
-                                        snapshot.file().map(|file| file.path().as_ref()),
-                                    ) {
-                                        query
-                                            .search(&snapshot, None)
-                                            .await
-                                            .iter()
-                                            .map(|range| {
-                                                snapshot.anchor_before(range.start)
-                                                    ..snapshot.anchor_after(range.end)
-                                            })
-                                            .collect()
-                                    } else {
-                                        Vec::new()
-                                    };
-                                    if !buffer_matches.is_empty() {
-                                        worker_matched_buffers
-                                            .insert(buffer.clone(), buffer_matches);
-                                    }
-                                }
-                            });
-                        }
-                    })
-                    .await;
-                Ok(matched_buffers.into_iter().flatten().collect())
-            })
+            self.search_local(query, cx)
         } else if let Some(project_id) = self.remote_id() {
+            let (tx, rx) = smol::channel::unbounded();
             let request = self.client.request(query.to_proto(project_id));
             cx.spawn(|this, mut cx| async move {
                 let response = request.await?;
@@ -5226,11 +5144,301 @@ impl Project {
                         .or_insert(Vec::new())
                         .push(start..end)
                 }
-                Ok(result)
-            })
-        } else {
-            Task::ready(Ok(Default::default()))
+                for (buffer, ranges) in result {
+                    let _ = tx.send((buffer, ranges)).await;
                 }
+                Result::<(), anyhow::Error>::Ok(())
+            })
+            .detach_and_log_err(cx);
+            rx
+        } else {
+            unimplemented!();
+        }
+    }
+
+    pub fn search_local(
+        &self,
+        query: SearchQuery,
+        cx: &mut ModelContext<Self>,
+    ) -> Receiver<(ModelHandle<Buffer>, Vec<Range<Anchor>>)> {
+        // Local search is split into several phases.
+        // TL;DR is that we do 2 passes; initial pass to pick files which contain at least one match
+        // and the second phase that finds positions of all the matches found in the candidate files.
+        // The Receiver obtained from this function returns matches sorted by buffer path. Files without a buffer path are reported first.
+        //
+        // It gets a bit hairy though, because we must account for files that do not have a persistent representation
+        // on FS. Namely, if you have an untitled buffer or unsaved changes in a buffer, we want to scan that too.
+        //
+        // 1. We initialize a queue of match candidates and feed all opened buffers into it (== unsaved files / untitled buffers).
+        //    Then, we go through a worktree and check for files that do match a predicate. If the file had an opened version, we skip the scan
+        //    of FS version for that file altogether - after all, what we have in memory is more up-to-date than what's in FS.
+        // 2. At this point, we have a list of all potentially matching buffers/files.
+        //    We sort that list by buffer path - this list is retained for later use.
+        //    We ensure that all buffers are now opened and available in project.
+        // 3. We run a scan over all the candidate buffers on multiple background threads.
+        //    We cannot assume that there will even be a match - while at least one match
+        //    is guaranteed for files obtained from FS, the buffers we got from memory (unsaved files/unnamed buffers) might not have a match at all.
+        //    There is also an auxilliary background thread responsible for result gathering.
+        //    This is where the sorted list of buffers comes into play to maintain sorted order; Whenever this background thread receives a notification (buffer has/doesn't have matches),
+        //    it keeps it around. It reports matches in sorted order, though it accepts them in unsorted order as well.
+        //    As soon as the match info on next position in sorted order becomes available, it reports it (if it's a match) or skips to the next
+        //    entry - which might already be available thanks to out-of-order processing.
+        //
+        // We could also report matches fully out-of-order, without maintaining a sorted list of matching paths.
+        // This however would mean that project search (that is the main user of this function) would have to do the sorting itself, on the go.
+        // This isn't as straightforward as running an insertion sort sadly, and would also mean that it would have to care about maintaining match index
+        // in face of constantly updating list of sorted matches.
+        // Meanwhile, this implementation offers index stability, since the matches are already reported in a sorted order.
+        let snapshots = self
+            .visible_worktrees(cx)
+            .filter_map(|tree| {
+                let tree = tree.read(cx).as_local()?;
+                Some(tree.snapshot())
+            })
+            .collect::<Vec<_>>();
+
+        let background = cx.background().clone();
+        let path_count: usize = snapshots.iter().map(|s| s.visible_file_count()).sum();
+        if path_count == 0 {
+            let (_, rx) = smol::channel::bounded(1024);
+            return rx;
+        }
+        let workers = background.num_cpus().min(path_count);
+        let (matching_paths_tx, matching_paths_rx) = smol::channel::bounded(1024);
+        let mut unnamed_files = vec![];
+        let opened_buffers = self
+            .opened_buffers
+            .iter()
+            .filter_map(|(_, b)| {
+                let buffer = b.upgrade(cx)?;
+                let snapshot = buffer.read_with(cx, |buffer, _| buffer.snapshot());
+                if let Some(path) = snapshot.file().map(|file| file.path()) {
+                    Some((path.clone(), (buffer, snapshot)))
+                } else {
+                    unnamed_files.push(buffer);
+                    None
+                }
+            })
+            .collect();
+        cx.background()
+            .spawn(Self::background_search(
+                unnamed_files,
+                opened_buffers,
+                cx.background().clone(),
+                self.fs.clone(),
+                workers,
+                query.clone(),
+                path_count,
+                snapshots,
+                matching_paths_tx,
+            ))
+            .detach();
+
+        let (buffers, buffers_rx) = Self::sort_candidates_and_open_buffers(matching_paths_rx, cx);
+        let background = cx.background().clone();
+        let (result_tx, result_rx) = smol::channel::bounded(1024);
+        cx.background()
+            .spawn(async move {
+                let Ok(buffers) = buffers.await else {
+                    return;
+                };
+
+                let buffers_len = buffers.len();
+                if buffers_len == 0 {
+                    return;
+                }
+                let query = &query;
+                let (finished_tx, mut finished_rx) = smol::channel::unbounded();
+                background
+                    .scoped(|scope| {
+                        #[derive(Clone)]
+                        struct FinishedStatus {
+                            entry: Option<(ModelHandle<Buffer>, Vec<Range<Anchor>>)>,
+                            buffer_index: SearchMatchCandidateIndex,
+                        }
+
+                        for _ in 0..workers {
+                            let finished_tx = finished_tx.clone();
+                            let mut buffers_rx = buffers_rx.clone();
+                            scope.spawn(async move {
+                                while let Some((entry, buffer_index)) = buffers_rx.next().await {
+                                    let buffer_matches = if let Some((_, snapshot)) = entry.as_ref()
+                                    {
+                                        if query.file_matches(
+                                            snapshot.file().map(|file| file.path().as_ref()),
+                                        ) {
+                                            query
+                                                .search(&snapshot, None)
+                                                .await
+                                                .iter()
+                                                .map(|range| {
+                                                    snapshot.anchor_before(range.start)
+                                                        ..snapshot.anchor_after(range.end)
+                                                })
+                                                .collect()
+                                        } else {
+                                            Vec::new()
+                                        }
+                                    } else {
+                                        Vec::new()
+                                    };
+
+                                    let status = if !buffer_matches.is_empty() {
+                                        let entry = if let Some((buffer, _)) = entry.as_ref() {
+                                            Some((buffer.clone(), buffer_matches))
+                                        } else {
+                                            None
+                                        };
+                                        FinishedStatus {
+                                            entry,
+                                            buffer_index,
+                                        }
+                                    } else {
+                                        FinishedStatus {
+                                            entry: None,
+                                            buffer_index,
+                                        }
+                                    };
+                                    if finished_tx.send(status).await.is_err() {
+                                        break;
+                                    }
+                                }
+                            });
+                        }
+                        // Report sorted matches
+                        scope.spawn(async move {
+                            let mut current_index = 0;
+                            let mut scratch = vec![None; buffers_len];
+                            while let Some(status) = finished_rx.next().await {
+                                debug_assert!(
+                                    scratch[status.buffer_index].is_none(),
+                                    "Got match status of position {} twice",
+                                    status.buffer_index
+                                );
+                                let index = status.buffer_index;
+                                scratch[index] = Some(status);
+                                while current_index < buffers_len {
+                                    let Some(current_entry) = scratch[current_index].take() else {
+                                        // We intentionally **do not** increment `current_index` here. When next element arrives
+                                        // from `finished_rx`, we will inspect the same position again, hoping for it to be Some(_)
+                                        // this time.
+                                        break;
+                                    };
+                                    if let Some(entry) = current_entry.entry {
+                                        result_tx.send(entry).await.log_err();
+                                    }
+                                    current_index += 1;
+                                }
+                                if current_index == buffers_len {
+                                    break;
+                                }
+                            }
+                        });
+                    })
+                    .await;
+            })
+            .detach();
+        result_rx
+    }
+    /// Pick paths that might potentially contain a match of a given search query.
+    async fn background_search(
+        unnamed_buffers: Vec<ModelHandle<Buffer>>,
+        opened_buffers: HashMap<Arc<Path>, (ModelHandle<Buffer>, BufferSnapshot)>,
+        background: Arc<Background>,
+        fs: Arc<dyn Fs>,
+        workers: usize,
+        query: SearchQuery,
+        path_count: usize,
+        snapshots: Vec<LocalSnapshot>,
+        matching_paths_tx: Sender<SearchMatchCandidate>,
+    ) {
+        let fs = &fs;
+        let query = &query;
+        let matching_paths_tx = &matching_paths_tx;
+        let snapshots = &snapshots;
+        let paths_per_worker = (path_count + workers - 1) / workers;
+        for buffer in unnamed_buffers {
+            matching_paths_tx
+                .send(SearchMatchCandidate::OpenBuffer {
+                    buffer: buffer.clone(),
+                    path: None,
+                })
+                .await
+                .log_err();
+        }
+        for (path, (buffer, _)) in opened_buffers.iter() {
+            matching_paths_tx
+                .send(SearchMatchCandidate::OpenBuffer {
+                    buffer: buffer.clone(),
+                    path: Some(path.clone()),
+                })
+                .await
+                .log_err();
+        }
+        background
+            .scoped(|scope| {
+                for worker_ix in 0..workers {
+                    let worker_start_ix = worker_ix * paths_per_worker;
+                    let worker_end_ix = worker_start_ix + paths_per_worker;
+                    let unnamed_buffers = opened_buffers.clone();
+                    scope.spawn(async move {
+                        let mut snapshot_start_ix = 0;
+                        let mut abs_path = PathBuf::new();
+                        for snapshot in snapshots {
+                            let snapshot_end_ix = snapshot_start_ix + snapshot.visible_file_count();
+                            if worker_end_ix <= snapshot_start_ix {
+                                break;
+                            } else if worker_start_ix > snapshot_end_ix {
+                                snapshot_start_ix = snapshot_end_ix;
+                                continue;
+                            } else {
+                                let start_in_snapshot =
+                                    worker_start_ix.saturating_sub(snapshot_start_ix);
+                                let end_in_snapshot =
+                                    cmp::min(worker_end_ix, snapshot_end_ix) - snapshot_start_ix;
+
+                                for entry in snapshot
+                                    .files(false, start_in_snapshot)
+                                    .take(end_in_snapshot - start_in_snapshot)
+                                {
+                                    if matching_paths_tx.is_closed() {
+                                        break;
+                                    }
+                                    if unnamed_buffers.contains_key(&entry.path) {
+                                        continue;
+                                    }
+                                    let matches = if query.file_matches(Some(&entry.path)) {
+                                        abs_path.clear();
+                                        abs_path.push(&snapshot.abs_path());
+                                        abs_path.push(&entry.path);
+                                        if let Some(file) = fs.open_sync(&abs_path).await.log_err()
+                                        {
+                                            query.detect(file).unwrap_or(false)
+                                        } else {
+                                            false
+                                        }
+                                    } else {
+                                        false
+                                    };
+
+                                    if matches {
+                                        let project_path = SearchMatchCandidate::Path {
+                                            worktree_id: snapshot.id(),
+                                            path: entry.path.clone(),
+                                        };
+                                        if matching_paths_tx.send(project_path).await.is_err() {
+                                            break;
+                                        }
+                                    }
+                                }
+
+                                snapshot_start_ix = snapshot_end_ix;
+                            }
+                        }
+                    });
+                }
+            })
+            .await;
     }
 
     // TODO: Wire this up to allow selecting a server?
@@ -5307,6 +5515,61 @@ impl Project {
         Task::ready(Ok(Default::default()))
     }
 
+    fn sort_candidates_and_open_buffers(
+        mut matching_paths_rx: Receiver<SearchMatchCandidate>,
+        cx: &mut ModelContext<Self>,
+    ) -> (
+        futures::channel::oneshot::Receiver<Vec<SearchMatchCandidate>>,
+        Receiver<(
+            Option<(ModelHandle<Buffer>, BufferSnapshot)>,
+            SearchMatchCandidateIndex,
+        )>,
+    ) {
+        let (buffers_tx, buffers_rx) = smol::channel::bounded(1024);
+        let (sorted_buffers_tx, sorted_buffers_rx) = futures::channel::oneshot::channel();
+        cx.spawn(|this, cx| async move {
+            let mut buffers = vec![];
+            while let Some(entry) = matching_paths_rx.next().await {
+                buffers.push(entry);
+            }
+            buffers.sort_by_key(|candidate| candidate.path());
+            let matching_paths = buffers.clone();
+            let _ = sorted_buffers_tx.send(buffers);
+            for (index, candidate) in matching_paths.into_iter().enumerate() {
+                if buffers_tx.is_closed() {
+                    break;
+                }
+                let this = this.clone();
+                let buffers_tx = buffers_tx.clone();
+                cx.spawn(|mut cx| async move {
+                    let buffer = match candidate {
+                        SearchMatchCandidate::OpenBuffer { buffer, .. } => Some(buffer),
+                        SearchMatchCandidate::Path { worktree_id, path } => this
+                            .update(&mut cx, |this, cx| {
+                                this.open_buffer((worktree_id, path), cx)
+                            })
+                            .await
+                            .log_err(),
+                    };
+                    if let Some(buffer) = buffer {
+                        let snapshot = buffer.read_with(&cx, |buffer, _| buffer.snapshot());
+                        buffers_tx
+                            .send((Some((buffer, snapshot)), index))
+                            .await
+                            .log_err();
+                    } else {
+                        buffers_tx.send((None, index)).await.log_err();
+                    }
+
+                    Ok::<_, anyhow::Error>(())
+                })
+                .detach();
+            }
+        })
+        .detach();
+        (sorted_buffers_rx, buffers_rx)
+    }
+
     pub fn find_or_create_local_worktree(
         &mut self,
         abs_path: impl AsRef<Path>,
@@ -5930,6 +6193,7 @@ impl Project {
         let collaborator = Collaborator::from_proto(collaborator)?;
         this.update(&mut cx, |this, cx| {
             this.shared_buffers.remove(&collaborator.peer_id);
+            cx.emit(Event::CollaboratorJoined(collaborator.peer_id));
             this.collaborators
                 .insert(collaborator.peer_id, collaborator);
             cx.notify();
@@ -6813,6 +7077,40 @@ impl Project {
         }))
     }
 
+    async fn handle_resolve_inlay_hint(
+        this: ModelHandle<Self>,
+        envelope: TypedEnvelope<proto::ResolveInlayHint>,
+        _: Arc<Client>,
+        mut cx: AsyncAppContext,
+    ) -> Result<proto::ResolveInlayHintResponse> {
+        let proto_hint = envelope
+            .payload
+            .hint
+            .expect("incorrect protobuf resolve inlay hint message: missing the inlay hint");
+        let hint = InlayHints::proto_to_project_hint(proto_hint)
+            .context("resolved proto inlay hint conversion")?;
+        let buffer = this.update(&mut cx, |this, cx| {
+            this.opened_buffers
+                .get(&envelope.payload.buffer_id)
+                .and_then(|buffer| buffer.upgrade(cx))
+                .ok_or_else(|| anyhow!("unknown buffer id {}", envelope.payload.buffer_id))
+        })?;
+        let response_hint = this
+            .update(&mut cx, |project, cx| {
+                project.resolve_inlay_hint(
+                    hint,
+                    buffer,
+                    LanguageServerId(envelope.payload.language_server_id as usize),
+                    cx,
+                )
+            })
+            .await
+            .context("inlay hints fetch")?;
+        Ok(proto::ResolveInlayHintResponse {
+            hint: Some(InlayHints::project_to_proto_hint(response_hint)),
+        })
+    }
+
     async fn handle_refresh_inlay_hints(
         this: ModelHandle<Self>,
         _: TypedEnvelope<proto::RefreshInlayHints>,
@@ -6891,17 +7189,17 @@ impl Project {
     ) -> Result<proto::SearchProjectResponse> {
         let peer_id = envelope.original_sender_id()?;
         let query = SearchQuery::from_proto(envelope.payload)?;
-        let result = this
-            .update(&mut cx, |this, cx| this.search(query, cx))
-            .await?;
+        let mut result = this.update(&mut cx, |this, cx| this.search(query, cx));
 
-        this.update(&mut cx, |this, cx| {
+        cx.spawn(|mut cx| async move {
             let mut locations = Vec::new();
-            for (buffer, ranges) in result {
+            while let Some((buffer, ranges)) = result.next().await {
                 for range in ranges {
                     let start = serialize_anchor(&range.start);
                     let end = serialize_anchor(&range.end);
-                    let buffer_id = this.create_buffer_for_peer(&buffer, peer_id, cx);
+                    let buffer_id = this.update(&mut cx, |this, cx| {
+                        this.create_buffer_for_peer(&buffer, peer_id, cx)
+                    });
                     locations.push(proto::Location {
                         buffer_id,
                         start: Some(start),
@@ -6911,6 +7209,7 @@ impl Project {
             }
             Ok(proto::SearchProjectResponse { locations })
         })
+        .await
     }
 
     async fn handle_open_buffer_for_symbol(
@@ -7576,7 +7875,7 @@ impl Project {
         self.language_servers_for_buffer(buffer, cx).next()
     }
 
-    fn language_server_for_buffer(
+    pub fn language_server_for_buffer(
         &self,
         buffer: &Buffer,
         server_id: LanguageServerId,
@@ -7756,6 +8055,7 @@ impl Collaborator {
         Ok(Self {
             peer_id: message.peer_id.ok_or_else(|| anyhow!("invalid peer id"))?,
             replica_id: message.replica_id as ReplicaId,
+            user_id: message.user_id as UserId,
         })
     }
 }

crates/project/src/project_tests.rs

@@ -1,4 +1,4 @@
-use crate::{search::PathMatcher, worktree::WorktreeHandle, Event, *};
+use crate::{search::PathMatcher, worktree::WorktreeModelHandle, Event, *};
 use fs::{FakeFs, LineEnding, RealFs};
 use futures::{future, StreamExt};
 use gpui::{executor::Deterministic, test::subscribe, AppContext};
@@ -3953,11 +3953,12 @@ async fn search(
     query: SearchQuery,
     cx: &mut gpui::TestAppContext,
 ) -> Result<HashMap<String, Vec<Range<usize>>>> {
-    let results = project
-        .update(cx, |project, cx| project.search(query, cx))
-        .await?;
-
-    Ok(results
+    let mut search_rx = project.update(cx, |project, cx| project.search(query, cx));
+    let mut result = HashMap::default();
+    while let Some((buffer, range)) = search_rx.next().await {
+        result.entry(buffer).or_insert(range);
+    }
+    Ok(result
         .into_iter()
         .map(|(buffer, ranges)| {
             buffer.read_with(cx, |buffer, _| {

crates/project/src/terminals.rs

@@ -1,7 +1,13 @@
 use crate::Project;
 use gpui::{AnyWindowHandle, ModelContext, ModelHandle, WeakModelHandle};
-use std::path::PathBuf;
-use terminal::{Terminal, TerminalBuilder, TerminalSettings};
+use std::path::{Path, PathBuf};
+use terminal::{
+    terminal_settings::{self, TerminalSettings, VenvSettingsContent},
+    Terminal, TerminalBuilder,
+};
+
+#[cfg(target_os = "macos")]
+use std::os::unix::ffi::OsStrExt;
 
 pub struct Terminals {
     pub(crate) local_handles: Vec<WeakModelHandle<terminal::Terminal>>,
@@ -20,10 +26,12 @@ impl Project {
             ));
         } else {
             let settings = settings::get::<TerminalSettings>(cx);
+            let python_settings = settings.detect_venv.clone();
+            let shell = settings.shell.clone();
 
             let terminal = TerminalBuilder::new(
                 working_directory.clone(),
-                settings.shell.clone(),
+                shell.clone(),
                 settings.env.clone(),
                 Some(settings.blinking.clone()),
                 settings.alternate_scroll,
@@ -47,6 +55,15 @@ impl Project {
                 })
                 .detach();
 
+                if let Some(python_settings) = &python_settings.as_option() {
+                    let activate_script_path =
+                        self.find_activate_script_path(&python_settings, working_directory);
+                    self.activate_python_virtual_environment(
+                        activate_script_path,
+                        &terminal_handle,
+                        cx,
+                    );
+                }
                 terminal_handle
             });
 
@@ -54,6 +71,50 @@ impl Project {
         }
     }
 
+    pub fn find_activate_script_path(
+        &mut self,
+        settings: &VenvSettingsContent,
+        working_directory: Option<PathBuf>,
+    ) -> Option<PathBuf> {
+        // When we are unable to resolve the working directory, the terminal builder
+        // defaults to '/'. We should probably encode this directly somewhere, but for
+        // now, let's just hard code it here.
+        let working_directory = working_directory.unwrap_or_else(|| Path::new("/").to_path_buf());
+        let activate_script_name = match settings.activate_script {
+            terminal_settings::ActivateScript::Default => "activate",
+            terminal_settings::ActivateScript::Csh => "activate.csh",
+            terminal_settings::ActivateScript::Fish => "activate.fish",
+        };
+
+        for virtual_environment_name in settings.directories {
+            let mut path = working_directory.join(virtual_environment_name);
+            path.push("bin/");
+            path.push(activate_script_name);
+
+            if path.exists() {
+                return Some(path);
+            }
+        }
+
+        None
+    }
+
+    fn activate_python_virtual_environment(
+        &mut self,
+        activate_script: Option<PathBuf>,
+        terminal_handle: &ModelHandle<Terminal>,
+        cx: &mut ModelContext<Project>,
+    ) {
+        if let Some(activate_script) = activate_script {
+            // Paths are not strings so we need to jump through some hoops to format the command without `format!`
+            let mut command = Vec::from("source ".as_bytes());
+            command.extend_from_slice(activate_script.as_os_str().as_bytes());
+            command.push(b'\n');
+
+            terminal_handle.update(cx, |this, _| this.input_bytes(command));
+        }
+    }
+
     pub fn local_terminal_handles(&self) -> &Vec<WeakModelHandle<terminal::Terminal>> {
         &self.terminals.local_handles
     }

crates/project/src/worktree.rs

@@ -2317,7 +2317,8 @@ impl BackgroundScannerState {
         for changed_path in changed_paths {
             let Some(dot_git_dir) = changed_path
                 .ancestors()
-                .find(|ancestor| ancestor.file_name() == Some(&*DOT_GIT)) else {
+                .find(|ancestor| ancestor.file_name() == Some(&*DOT_GIT))
+            else {
                 continue;
             };
 
@@ -2348,7 +2349,10 @@ impl BackgroundScannerState {
                     let Some(work_dir) = self
                         .snapshot
                         .entry_for_id(entry_id)
-                        .map(|entry| RepositoryWorkDirectory(entry.path.clone())) else { continue };
+                        .map(|entry| RepositoryWorkDirectory(entry.path.clone()))
+                    else {
+                        continue;
+                    };
 
                     log::info!("reload git repository {:?}", dot_git_dir);
                     let repository = repository.repo_ptr.lock();
@@ -4026,7 +4030,7 @@ struct UpdateIgnoreStatusJob {
     scan_queue: Sender<ScanJob>,
 }
 
-pub trait WorktreeHandle {
+pub trait WorktreeModelHandle {
     #[cfg(any(test, feature = "test-support"))]
     fn flush_fs_events<'a>(
         &self,
@@ -4034,7 +4038,7 @@ pub trait WorktreeHandle {
     ) -> futures::future::LocalBoxFuture<'a, ()>;
 }
 
-impl WorktreeHandle for ModelHandle<Worktree> {
+impl WorktreeModelHandle for ModelHandle<Worktree> {
     // When the worktree's FS event stream sometimes delivers "redundant" events for FS changes that
     // occurred before the worktree was constructed. These events can cause the worktree to perform
     // extra directory scans, and emit extra scan-state notifications.

crates/project/src/worktree_tests.rs

@@ -1,5 +1,5 @@
 use crate::{
-    worktree::{Event, Snapshot, WorktreeHandle},
+    worktree::{Event, Snapshot, WorktreeModelHandle},
     Entry, EntryKind, PathChange, Worktree,
 };
 use anyhow::Result;