Decouple recommended plugins from tool suggestions (#35839)

## What changed

- Add the stable, disabled-by-default `recommended_plugins` feature flag.
- Load recommended plugin candidates when apps and plugins are enabled and
  either `tool_suggest` or `recommended_plugins` is active.
- Keep the `request_plugin_install` tool gated by `tool_suggest`.

## Testing

- Cover the first turn after external login with `tool_suggest` both enabled
  and disabled, including the expected install-tool availability.

GitOrigin-RevId: 06d9a1c2e8dd2498a47796d833eb6d25ba528351

codex-rs/app-server/tests/suite/v2/recommended_plugins.rs

@@ -27,8 +27,31 @@ use wiremock::matchers::query_param;
 const DEFAULT_READ_TIMEOUT: Duration = Duration::from_secs(20);
 const WORKSPACE_ID: &str = "123e4567-e89b-42d3-a456-426614174010";
 
+enum ToolSuggestFeature {
+    Enabled,
+    Disabled,
+}
+
 #[tokio::test]
 async fn first_turn_after_external_login_waits_for_recommended_plugins() -> Result<()> {
+    recommended_plugins_after_external_login(ToolSuggestFeature::Enabled).await
+}
+
+#[tokio::test]
+async fn first_turn_after_external_login_waits_for_recommended_plugins_without_tool_suggest()
+-> Result<()> {
+    recommended_plugins_after_external_login(ToolSuggestFeature::Disabled).await
+}
+
+async fn recommended_plugins_after_external_login(
+    tool_suggest_feature: ToolSuggestFeature,
+) -> Result<()> {
+    let tool_suggest_enabled = matches!(tool_suggest_feature, ToolSuggestFeature::Enabled);
+    let recommended_plugins_config = if tool_suggest_enabled {
+        ""
+    } else {
+        "recommended_plugins = true\n"
+    };
     let server = responses::start_mock_server().await;
     let apps_server = AppsTestServer::mount(&server).await?;
     Mock::given(method("GET"))
@@ -68,7 +91,9 @@ async fn first_turn_after_external_login_waits_for_recommended_plugins() -> Resu
     let config = std::fs::read_to_string(&config_path)?;
     std::fs::write(
         config_path,
-        format!("{config}\n[features]\napps = true\nplugins = true\ntool_suggest = true\n"),
+        format!(
+            "{config}\n[features]\napps = true\nplugins = true\ntool_suggest = {tool_suggest_enabled}\n{recommended_plugins_config}"
+        ),
     )?;
 
     let sqlite_home = codex_home.path().to_string_lossy();
@@ -158,7 +183,10 @@ async fn first_turn_after_external_login_waits_for_recommended_plugins() -> Resu
         .flatten()
         .filter_map(|tool| tool.get("name").and_then(Value::as_str))
         .collect::<Vec<_>>();
-    assert!(tool_names.contains(&"request_plugin_install"));
+    assert_eq!(
+        tool_names.contains(&"request_plugin_install"),
+        tool_suggest_enabled
+    );
     assert!(!tool_names.contains(&"list_available_plugins_to_install"));
     Ok(())
 }

codex-rs/core/config.schema.json

@@ -633,6 +633,9 @@
             "realtime_conversation": {
               "type": "boolean"
             },
+            "recommended_plugins": {
+              "type": "boolean"
+            },
             "remote_compaction_v2": {
               "type": "boolean"
             },
@@ -5190,6 +5193,9 @@
         "realtime_conversation": {
           "type": "boolean"
         },
+        "recommended_plugins": {
+          "type": "boolean"
+        },
         "remote_compaction_v2": {
           "type": "boolean"
         },

codex-rs/core/src/session/mod.rs

@@ -3422,23 +3422,27 @@ impl Session {
             .plugins_manager
             .plugins_for_config(&turn_context.config.plugins_config_input())
             .await;
-        let recommended_plugin_candidates =
-            if crate::tools::spec_plan::tool_suggest_enabled(turn_context) {
-                let auth = self.services.auth_manager.auth().await;
-                let plugins_config = turn_context.config.plugins_config_input();
-                self.services
-                    .plugins_manager
-                    .recommended_plugin_candidates_for_config(RecommendedPluginCandidatesInput {
-                        plugins_config: &plugins_config,
-                        loaded_plugins: &loaded_plugins,
-                        auth: auth.as_ref(),
-                        disabled_tools: &turn_context.config.tool_suggest.disabled_tools,
-                        app_server_client_name: turn_context.app_server_client_name.as_deref(),
-                    })
-                    .await
-            } else {
-                None
-            };
+        let features = turn_context.config.features.get();
+        let recommended_plugin_candidates = if features.enabled(Feature::Apps)
+            && features.enabled(Feature::Plugins)
+            && (features.enabled(Feature::ToolSuggest)
+                || features.enabled(Feature::RecommendedPlugins))
+        {
+            let auth = self.services.auth_manager.auth().await;
+            let plugins_config = turn_context.config.plugins_config_input();
+            self.services
+                .plugins_manager
+                .recommended_plugin_candidates_for_config(RecommendedPluginCandidatesInput {
+                    plugins_config: &plugins_config,
+                    loaded_plugins: &loaded_plugins,
+                    auth: auth.as_ref(),
+                    disabled_tools: &turn_context.config.tool_suggest.disabled_tools,
+                    app_server_client_name: turn_context.app_server_client_name.as_deref(),
+                })
+                .await
+        } else {
+            None
+        };
         if let Some(recommended_plugins) = recommended_plugin_candidates
             .as_deref()
             .and_then(RecommendedPluginsInstructions::from_plugins)

codex-rs/features/src/lib.rs

@@ -176,6 +176,8 @@ pub enum Feature {
     NonPrefixedMcpToolNames,
     /// Enable discoverable tool suggestions for apps.
     ToolSuggest,
+    /// Include recommended plugins in model-visible context.
+    RecommendedPlugins,
     /// Enable plugins.
     Plugins,
     /// Discover selected-root plugin and skill manifests through one high-level exec-server RPC.
@@ -1161,6 +1163,12 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::Stable,
         default_enabled: true,
     },
+    FeatureSpec {
+        id: Feature::RecommendedPlugins,
+        key: "recommended_plugins",
+        stage: Stage::Stable,
+        default_enabled: false,
+    },
     FeatureSpec {
         id: Feature::Plugins,
         key: "plugins",