Hydrate recommended plugin metadata on selection (#39143)

## What changed

- Fetch recommendations from the Codex-specific `/ps/plugins/suggested/codex` endpoint and parse its compact response shape.
- Fetch the selected plugin's details before presenting an install request, using them to verify availability and populate connector metadata.
- Skip install elicitation when the selected recommendation is no longer available, and return a retryable response when its metadata cannot be verified.

## Testing

- Cover the new recommendation route and response shape.
- Cover metadata hydration for available plugins and rejection of unavailable plugins.

GitOrigin-RevId: 2b0e2d70572aae2b7cd8e458b42e9dd14be3dbaf

codex-rs/core/src/tools/handlers/request_plugin_install.rs

@@ -177,6 +177,31 @@ impl RequestPluginInstallHandler {
                     "{argument_name} must match one of {source}"
                 ))
             })?;
+        let tool = if self.presentation == ToolSuggestPresentation::RecommendationContext {
+            let plugin_id = tool.id().to_string();
+            let auth = session.services.auth_manager.auth().await;
+            let plugins_config = turn.config.plugins_config_input();
+            match codex_core_plugins::hydrate_selected_recommended_plugin_install_metadata(
+                &plugins_config,
+                auth.as_ref(),
+                tool,
+            )
+            .await
+            {
+                Ok(Some(tool)) => tool,
+                Ok(None) => return Err(recommended_plugins_no_longer_available()),
+                Err(err) => {
+                    warn!(
+                        plugin_id,
+                        error = %err,
+                        "failed to hydrate selected recommended plugin install metadata"
+                    );
+                    return Err(recommended_plugin_metadata_retryable());
+                }
+            }
+        } else {
+            tool
+        };
         let tool_type = tool.tool_type();
 
         let suggestion_id = format!("request_plugin_install_{call_id}");
@@ -286,6 +311,18 @@ impl RequestPluginInstallHandler {
     }
 }
 
+fn recommended_plugins_no_longer_available() -> FunctionCallError {
+    FunctionCallError::RespondToModel(
+        "The recommended plugins for this turn are no longer available.".to_string(),
+    )
+}
+
+fn recommended_plugin_metadata_retryable() -> FunctionCallError {
+    FunctionCallError::RespondToModel(
+        "The selected recommended plugin could not be verified right now. Retry request_plugin_install with the same plugin_id.".to_string(),
+    )
+}
+
 impl CoreToolRuntime for RequestPluginInstallHandler {}
 
 async fn maybe_persist_disabled_install_request(