Allow extensions to control the redirect policy for the HTTP client (#16162)

This PR extends the extension API with support for controlling the
redirect policy used by the HTTP client.

Release Notes:

- N/A

crates/extension/src/wasm_host/wit/since_v0_1_0.rs

@@ -136,7 +136,7 @@ impl http_client::Host for WasmState {
     ) -> wasmtime::Result<Result<http_client::HttpResponse, String>> {
         maybe!(async {
             let url = &request.url;
-            let request = convert_request(&request, true)?;
+            let request = convert_request(&request)?;
             let mut response = self.host.http_client.send(request).await?;
 
             if response.status().is_client_error() || response.status().is_server_error() {
@@ -152,7 +152,7 @@ impl http_client::Host for WasmState {
         &mut self,
         request: http_client::HttpRequest,
     ) -> wasmtime::Result<Result<Resource<ExtensionHttpResponseStream>, String>> {
-        let request = convert_request(&request, true)?;
+        let request = convert_request(&request)?;
         let response = self.host.http_client.send(request);
         maybe!(async {
             let response = response.await?;
@@ -208,15 +208,14 @@ impl From<http_client::HttpMethod> for ::http_client::Method {
 
 fn convert_request(
     extension_request: &http_client::HttpRequest,
-    follow_redirects: bool,
 ) -> Result<::http_client::Request<AsyncBody>, anyhow::Error> {
     let mut request = ::http_client::Request::builder()
         .method(::http_client::Method::from(extension_request.method))
         .uri(&extension_request.url)
-        .redirect_policy(if follow_redirects {
-            RedirectPolicy::Follow
-        } else {
-            RedirectPolicy::None
+        .redirect_policy(match extension_request.redirect_policy {
+            http_client::RedirectPolicy::NoFollow => RedirectPolicy::None,
+            http_client::RedirectPolicy::FollowLimit(limit) => RedirectPolicy::Limit(limit),
+            http_client::RedirectPolicy::FollowAll => RedirectPolicy::Follow,
         });
     for (key, value) in &extension_request.headers {
         request = request.header(key, value);

crates/extension_api/src/extension_api.rs

@@ -21,6 +21,7 @@ pub use wit::{
     },
     zed::extension::http_client::{
         fetch, fetch_stream, HttpMethod, HttpRequest, HttpResponse, HttpResponseStream,
+        RedirectPolicy,
     },
     zed::extension::nodejs::{
         node_binary_path, npm_install_package, npm_package_installed_version,

crates/extension_api/wit/since_v0.1.0/http-client.wit

@@ -5,23 +5,44 @@ interface http-client {
         method: http-method,
         /// The URL to which the request should be made.
         url: string,
-        /// Headers for the request.
+        /// The headers for the request.
         headers: list<tuple<string, string>>,
         /// The request body.
         body: option<list<u8>>,
+        /// The policy to use for redirects.
+        redirect-policy: redirect-policy,
     }
 
     /// HTTP methods.
     enum http-method {
+        /// `GET`
         get,
-        post,
-        put,
-        delete,
+        /// `HEAD`
         head,
+        /// `POST`
+        post,
+        /// `PUT`
+        put,
+        /// `DELETE`
+        delete,
+        /// `OPTIONS`
         options,
+        /// `PATCH`
         patch,
     }
 
+    /// The policy for dealing with redirects received from the server.
+    variant redirect-policy {
+        /// Redirects from the server will not be followed.
+        ///
+        /// This is the default behavior.
+        no-follow,
+        /// Redirects from the server will be followed up to the specified limit.
+        follow-limit(u32),
+        /// All redirects from the server will be followed.
+        follow-all,
+    }
+
     /// An HTTP response.
     record http-response {
         /// The response headers.
@@ -36,7 +57,8 @@ interface http-client {
     /// An HTTP response stream.
     resource http-response-stream {
         /// Retrieves the next chunk of data from the response stream.
-        /// Returns None if the stream has ended.
+        ///
+        /// Returns `Ok(None)` if the stream has ended.
         next-chunk: func() -> result<option<list<u8>>, string>;
     }
 

extensions/gleam/src/gleam.rs

@@ -4,7 +4,8 @@ use std::{fs, io};
 use zed::lsp::CompletionKind;
 use zed::{
     CodeLabel, CodeLabelSpan, HttpMethod, HttpRequest, KeyValueStore, LanguageServerId,
-    SlashCommand, SlashCommandArgumentCompletion, SlashCommandOutput, SlashCommandOutputSection,
+    RedirectPolicy, SlashCommand, SlashCommandArgumentCompletion, SlashCommandOutput,
+    SlashCommandOutputSection,
 };
 use zed_extension_api::{self as zed, Result};
 
@@ -208,6 +209,7 @@ impl zed::Extension for GleamExtension {
                         "Zed (Gleam Extension)".to_string(),
                     )],
                     body: None,
+                    redirect_policy: RedirectPolicy::FollowAll,
                 })?;
 
                 let (markdown, _modules) =

extensions/gleam/src/hexdocs.rs

@@ -10,7 +10,9 @@ use html_to_markdown::{
     convert_html_to_markdown, HandleTag, HandlerOutcome, HtmlElement, MarkdownWriter,
     StartTagOutcome, TagHandler,
 };
-use zed_extension_api::{self as zed, HttpMethod, HttpRequest, KeyValueStore, Result};
+use zed_extension_api::{
+    self as zed, HttpMethod, HttpRequest, KeyValueStore, RedirectPolicy, Result,
+};
 
 pub fn index(package: String, database: &KeyValueStore) -> Result<()> {
     let headers = vec![(
@@ -23,6 +25,7 @@ pub fn index(package: String, database: &KeyValueStore) -> Result<()> {
         url: format!("https://hexdocs.pm/{package}"),
         headers: headers.clone(),
         body: None,
+        redirect_policy: RedirectPolicy::FollowAll,
     })?;
 
     let (package_root_markdown, modules) =
@@ -36,6 +39,7 @@ pub fn index(package: String, database: &KeyValueStore) -> Result<()> {
             url: format!("https://hexdocs.pm/{package}/{module}.html"),
             headers: headers.clone(),
             body: None,
+            redirect_policy: RedirectPolicy::FollowAll,
         })?;
 
         let (markdown, _modules) =