app-server: Allow enabling remote control in runtime (#16973)

Refresh the feature flag on writes to the config.

codex-rs/app-server/src/message_processor.rs

@@ -19,6 +19,7 @@ use crate::outgoing_message::ConnectionRequestId;
 use crate::outgoing_message::OutgoingMessageSender;
 use crate::outgoing_message::RequestContext;
 use crate::transport::AppServerTransport;
+use crate::transport::RemoteControlHandle;
 use async_trait::async_trait;
 use codex_analytics::AnalyticsEventsClient;
 use codex_analytics::AppServerRpcTransport;
@@ -170,6 +171,7 @@ pub(crate) struct MessageProcessor {
     config: Arc<Config>,
     config_warnings: Arc<Vec<ConfigWarningNotification>>,
     rpc_transport: AppServerRpcTransport,
+    remote_control_handle: Option<RemoteControlHandle>,
 }
 
 #[derive(Clone, Debug, Default)]
@@ -195,6 +197,7 @@ pub(crate) struct MessageProcessorArgs {
     pub(crate) session_source: SessionSource,
     pub(crate) auth_manager: Arc<AuthManager>,
     pub(crate) rpc_transport: AppServerRpcTransport,
+    pub(crate) remote_control_handle: Option<RemoteControlHandle>,
 }
 
 impl MessageProcessor {
@@ -215,6 +218,7 @@ impl MessageProcessor {
             session_source,
             auth_manager,
             rpc_transport,
+            remote_control_handle,
         } = args;
         auth_manager.set_external_auth(Arc::new(ExternalAuthRefreshBridge {
             outgoing: outgoing.clone(),
@@ -285,6 +289,7 @@ impl MessageProcessor {
             config,
             config_warnings: Arc::new(config_warnings),
             rpc_transport,
+            remote_control_handle,
         }
     }
 
@@ -969,13 +974,36 @@ impl MessageProcessor {
     ) {
         match result {
             Ok(response) => {
-                self.codex_message_processor.handle_config_mutation();
+                self.handle_config_mutation().await;
                 self.outgoing.send_response(request_id, response).await;
             }
             Err(error) => self.outgoing.send_error(request_id, error).await,
         }
     }
 
+    async fn handle_config_mutation(&self) {
+        self.codex_message_processor.handle_config_mutation();
+        let Some(remote_control_handle) = &self.remote_control_handle else {
+            return;
+        };
+
+        match self
+            .config_api
+            .load_latest_config(/*fallback_cwd*/ None)
+            .await
+        {
+            Ok(config) => {
+                remote_control_handle.set_enabled(config.features.enabled(Feature::RemoteControl));
+            }
+            Err(error) => {
+                tracing::warn!(
+                    "failed to load config for remote control enablement refresh after config mutation: {}",
+                    error.message
+                );
+            }
+        }
+    }
+
     async fn handle_config_requirements_read(&self, request_id: ConnectionRequestId) {
         match self.config_api.config_requirements_read().await {
             Ok(response) => self.outgoing.send_response(request_id, response).await,