wezterm cli now prefers to talk to main GUI instance

When spawned with no WEZTERM_UNIX_SOCKET environment set,
we now prefer to resolve the gui instance, falling back to
the mux if it doesn't look like the gui is running.

`wezterm cli --prefer-mux` will use the original behavior of
trying to resolve the path from the unix domain in the config.

docs/changelog.md

@@ -20,6 +20,7 @@ As features stabilize some brief notes about them will accumulate here.
 #### Changed
 
 * **Key Assignments now use Physical Key locations by default!!** follow the work in progress in [#1483](https://github.com/wez/wezterm/issues/1483)
+* `wezterm cli`, when run outside of a wezterm pane, now prefers to connect to the main GUI instance rather than background mux server. Use `wezterm cli --prefer-mux` to ignore the GUI instance and talk only to the mux server. See `wezterm cli --help` for additional information.
 
 #### Updated and Improved
 

wezterm-client/src/client.rs

@@ -1009,30 +1009,49 @@ impl Client {
         self.local_domain_id
     }
 
+    fn compute_unix_domain(
+        prefer_mux: bool,
+        class_name: &str,
+    ) -> anyhow::Result<config::UnixDomain> {
+        match std::env::var_os("WEZTERM_UNIX_SOCKET") {
+            Some(path) if !path.is_empty() => Ok(config::UnixDomain {
+                socket_path: Some(path.into()),
+                ..Default::default()
+            }),
+            Some(_) | None => {
+                if !prefer_mux {
+                    if let Ok(gui) = crate::discovery::resolve_gui_sock_path(class_name) {
+                        return Ok(config::UnixDomain {
+                            socket_path: Some(gui),
+                            no_serve_automatically: true,
+                            ..Default::default()
+                        });
+                    }
+                }
+
+                let config = configuration();
+                Ok(config
+                    .unix_domains
+                    .first()
+                    .ok_or_else(|| {
+                        anyhow!(
+                            "no default unix domain is configured and WEZTERM_UNIX_SOCKET \
+                             is not set in the environment"
+                        )
+                    })?
+                    .clone())
+            }
+        }
+    }
+
     pub fn new_default_unix_domain(
         initial: bool,
         ui: &mut ConnectionUI,
         no_auto_start: bool,
+        prefer_mux: bool,
+        class_name: &str,
     ) -> anyhow::Result<Self> {
-        let config = configuration();
-
-        let unix_dom = match std::env::var_os("WEZTERM_UNIX_SOCKET") {
-            Some(path) => config::UnixDomain {
-                socket_path: Some(path.into()),
-                ..Default::default()
-            },
-            None => config
-                .unix_domains
-                .first()
-                .ok_or_else(|| {
-                    anyhow!(
-                        "no default unix domain is configured and WEZTERM_UNIX_SOCKET \
-                        is not set in the environment"
-                    )
-                })?
-                .clone(),
-        };
-
+        let unix_dom = Self::compute_unix_domain(prefer_mux, class_name)?;
         Self::new_unix_domain(alloc_domain_id(), &unix_dom, initial, ui, no_auto_start)
     }
 

wezterm-gui-subcommands/src/lib.rs

@@ -2,6 +2,8 @@ use config::SshParameters;
 use std::ffi::OsString;
 use structopt::StructOpt;
 
+pub const DEFAULT_WINDOW_CLASS: &str = "org.wezfurlong.wezterm";
+
 /// Helper for parsing config overrides
 pub fn name_equals_value(arg: &str) -> Result<(String, String), String> {
     if let Some(eq) = arg.find('=') {

wezterm-gui/src/termwindow/mod.rs

@@ -66,7 +66,7 @@ use spawn::SpawnWhere;
 const ATLAS_SIZE: usize = 128;
 
 lazy_static::lazy_static! {
-    static ref WINDOW_CLASS: Mutex<String> = Mutex::new("org.wezfurlong.wezterm".to_owned());
+    static ref WINDOW_CLASS: Mutex<String> = Mutex::new(wezterm_gui_subcommands::DEFAULT_WINDOW_CLASS.to_owned());
 }
 
 pub const ICON_DATA: &'static [u8] = include_bytes!("../../../assets/icon/terminal.png");

wezterm/src/main.rs

@@ -90,6 +90,19 @@ struct CliCommand {
     #[structopt(long = "no-auto-start")]
     no_auto_start: bool,
 
+    /// Prefer connecting to a background mux server.
+    /// The default is to prefer connecting to a running
+    /// wezterm gui instance
+    #[structopt(long = "prefer-mux")]
+    prefer_mux: bool,
+
+    /// When connecting to a gui instance, if you started the
+    /// gui with `--class SOMETHING`, you should also pass
+    /// that same value here in order for the client to find
+    /// the correct gui instance.
+    #[structopt(long = "class")]
+    class: Option<String>,
+
     #[structopt(subcommand)]
     sub: CliSubCommand,
 }
@@ -373,9 +386,19 @@ fn delegate_to_gui(saver: UmaskSaver) -> anyhow::Result<()> {
 }
 
 async fn run_cli_async(config: config::ConfigHandle, cli: CliCommand) -> anyhow::Result<()> {
-    let initial = true;
     let mut ui = mux::connui::ConnectionUI::new_headless();
-    let client = Client::new_default_unix_domain(initial, &mut ui, cli.no_auto_start)?;
+    let initial = true;
+
+    let client = Client::new_default_unix_domain(
+        initial,
+        &mut ui,
+        cli.no_auto_start,
+        cli.prefer_mux,
+        cli.class
+            .as_deref()
+            .unwrap_or(wezterm_gui_subcommands::DEFAULT_WINDOW_CLASS),
+    )?;
+
     match cli.sub {
         CliSubCommand::List => {
             let cols = vec![