feat(core): Disable topic updates for subagents (#25567)

packages/core/src/agents/generalist-agent.ts

@@ -55,8 +55,9 @@ export const GeneralistAgent = (
     return {
       systemPrompt: getCoreSystemPrompt(
         context.config,
-        /*useMemory=*/ undefined,
+        /*userMemory=*/ undefined,
         /*interactiveOverride=*/ false,
+        /*topicUpdateNarrationOverride=*/ false,
       ),
       query: '${request}',
     };

packages/core/src/agents/local-executor.ts

@@ -82,6 +82,7 @@ import { CompleteTaskTool } from '../tools/complete-task.js';
 import {
   COMPLETE_TASK_TOOL_NAME,
   ACTIVATE_SKILL_TOOL_NAME,
+  UPDATE_TOPIC_TOOL_NAME,
 } from '../tools/definitions/base-declarations.js';
 
 /** A callback function to report on agent activity. */
@@ -189,6 +190,10 @@ export class LocalAgentExecutor<TOutput extends z.ZodTypeAny> {
         return;
       }
 
+      if (tool.name === UPDATE_TOPIC_TOOL_NAME) {
+        return;
+      }
+
       // Clone the tool, so it gets its own state and subagent messageBus
       const clonedTool = tool.clone(subagentMessageBus);
       agentToolRegistry.registerTool(clonedTool);