add persisted pi workflow extension

extensions/shared/child-session.ts

@@ -18,6 +18,7 @@ export const CHILD_EXCLUDED_TOOL_NAMES = [
   "subagent_check",
   "subagent_list",
   "workflow",
+  "pi_workflow",
   "ask_user",
 ] as const;
 
@@ -92,7 +93,10 @@ export interface DisposableChildSession {
 
 const childShutdowns = new WeakMap<object, Promise<void>>();
 
-function waitBounded(operation: Promise<unknown>, timeoutMs: number) {
+export function waitForChildOperation(
+  operation: Promise<unknown>,
+  timeoutMs = CHILD_SHUTDOWN_TIMEOUT_MS,
+) {
   let timer: ReturnType<typeof setTimeout> | undefined;
   const timeout = new Promise<void>((resolve) => {
     timer = setTimeout(resolve, timeoutMs);
@@ -124,7 +128,7 @@ export function shutdownAndDisposeChildSession(
   const shutdown = (async () => {
     try {
       if (session.extensionRunner.hasHandlers("session_shutdown")) {
-        await waitBounded(
+        await waitForChildOperation(
           session.extensionRunner.emit({
             type: "session_shutdown",
             reason: "quit",