fix(pi): converge worker failures and thinking state

electron/coding-runtime/pi/subagent-child.ts

@@ -26,7 +26,12 @@ import type {
   PiSubagentChildResult,
 } from './subagent';
 import { PiSubagentChildError } from './subagent';
-import { PiWorkerProcess, type PiWorkerProcessOptions, type PiWorkerStopResult } from './worker-process';
+import {
+  PiWorkerProcess,
+  type PiWorkerProcessOptions,
+  type PiWorkerStopReason,
+  type PiWorkerStopResult,
+} from './worker-process';
 import type { PiProcessError } from './process-errors';
 import type { PiManagedExtensionHost } from './extension-host';
 
@@ -41,7 +46,7 @@ export interface PiSubagentProcessAdapter {
   ): Promise<PiRpcResponse<T>>;
   subscribe(listener: (event: PiRpcEvent) => void): () => void;
   subscribeInvalidation(listener: (error: PiProcessError) => void): () => void;
-  stop(): Promise<PiWorkerStopResult>;
+  stop(reason: PiWorkerStopReason): Promise<PiWorkerStopResult>;
 }
 
 export interface PiManagedSubagentChildOpenerOptions {
@@ -134,11 +139,11 @@ class ManagedPiSubagentChild implements PiSubagentChild {
     }
   }
 
-  async stop(): Promise<void> {
+  async stop(reason: PiWorkerStopReason): Promise<void> {
     if (this.stopped) return;
     this.stopped = true;
     try {
-      await this.process.stop();
+      await this.process.stop(reason);
     } finally {
       await this.disposeExtension();
     }
@@ -214,6 +219,8 @@ export function createPiManagedSubagentChildOpener(
       ],
       env: { ...credential.env, ...extension.env },
       sensitiveValues: [...credential.sensitiveValues, ...extension.sensitiveValues],
+      conversationId: input.conversationId,
+      workerGeneration: input.workerGeneration,
     });
     try {
       await process.start();
@@ -221,7 +228,7 @@ export function createPiManagedSubagentChildOpener(
       if (!ready.success) throw new PiSubagentChildError('SUBAGENT_CHILD_START_FAILED');
       return new ManagedPiSubagentChild(input.taskId, process, extension.dispose);
     } catch (error) {
-      await process.stop().catch(() => undefined);
+      await process.stop('subagent_open_failure').catch(() => undefined);
       await extension.dispose();
       throw error;
     }