fix(agent): implement AgentProtocol disposal to prevent memory leaks

packages/cli/src/nonInteractiveCliAgentSession.ts

@@ -193,6 +193,7 @@ export async function runNonInteractive({
 
     let errorToHandle: unknown | undefined;
     let scheduler: Scheduler | undefined;
+    let session: LegacyAgentSession | undefined;
     let abortSession = () => {};
     try {
       consolePatcher.patch();
@@ -296,7 +297,7 @@ export async function runNonInteractive({
       }
 
       // Create LegacyAgentSession — owns the agentic loop
-      const session = new LegacyAgentSession({
+      session = new LegacyAgentSession({
         client: geminiClient,
         scheduler,
         config,
@@ -305,7 +306,7 @@ export async function runNonInteractive({
 
       // Wire Ctrl+C to session abort
       abortSession = () => {
-        void session.abort();
+        void session?.abort();
       };
       abortController.signal.addEventListener('abort', abortSession);
       if (abortController.signal.aborted) {
@@ -640,6 +641,7 @@ export async function runNonInteractive({
       cleanupStdinCancellation();
       abortController.signal.removeEventListener('abort', abortSession);
 
+      session?.dispose();
       scheduler?.dispose();
       consolePatcher.cleanup();
       coreEvents.off(CoreEvent.UserFeedback, handleUserFeedback);

packages/cli/src/ui/AppContainer.tsx

@@ -1180,6 +1180,10 @@ Logging in with Google... Restarting Gemini CLI to continue.
     [config, getPreferredEditor],
   );
 
+  useEffect(() => () => {
+      streamAgent?.dispose?.();
+    }, [streamAgent]);
+
   const activeStream = streamAgent
     ? // eslint-disable-next-line react-hooks/rules-of-hooks
       useAgentStream({

packages/core/src/agent/agent-session.ts

@@ -34,6 +34,10 @@ export class AgentSession implements AgentProtocol {
     return this._protocol.abort();
   }
 
+  dispose(): void {
+    this._protocol.dispose?.();
+  }
+
   get events(): readonly AgentEvent[] {
     return this._protocol.events;
   }

packages/core/src/agent/legacy-agent-session.ts

@@ -71,6 +71,7 @@ export class LegacyAgentProtocol implements AgentProtocol {
   private _agentEndEmitted = false;
   private _activeStreamId?: string;
   private _abortController = new AbortController();
+  private _disposalController = new AbortController();
   private _nextStreamIdOverride?: string;
   private _lastToolStatuses = new Map<string, ToolEventStatus>();
 
@@ -106,10 +107,16 @@ export class LegacyAgentProtocol implements AgentProtocol {
       this._config.messageBus.subscribe(
         MessageBusType.TOOL_CALLS_UPDATE,
         this._handleToolCallsUpdate.bind(this),
+        { signal: this._disposalController.signal },
       );
     }
   }
 
+  dispose(): void {
+    this._disposalController.abort();
+    void this.abort();
+  }
+
   get events(): readonly AgentEvent[] {
     return this._events;
   }

packages/core/src/agent/types.ts

@@ -37,6 +37,11 @@ export interface AgentProtocol extends Trajectory {
    */
   abort(): Promise<void>;
 
+  /**
+   * Disposes of the protocol, cleaning up any long-lived resources.
+   */
+  dispose?(): void;
+
   /**
    * AgentProtocol implements the Trajectory interface and can retrieve existing events.
    */