fix(agents): avoid synthetic tool-result writes on idle-timeout cleanup

src/agents/pi-embedded-runner/compact.ts

@@ -817,6 +817,7 @@ export async function compactEmbeddedPiSessionDirect(
         await flushPendingToolResultsAfterIdle({
           agent: session?.agent,
           sessionManager,
+          clearPendingOnTimeout: true,
         });
         session.dispose();
       }

src/agents/pi-embedded-runner/run/attempt.ts

@@ -1338,6 +1338,7 @@ export async function runEmbeddedAttempt(
         await flushPendingToolResultsAfterIdle({
           agent: activeSession?.agent,
           sessionManager,
+          clearPendingOnTimeout: true,
         });
         activeSession.dispose();
         throw err;
@@ -1904,6 +1905,7 @@ export async function runEmbeddedAttempt(
       await flushPendingToolResultsAfterIdle({
         agent: session?.agent,
         sessionManager,
+        clearPendingOnTimeout: true,
       });
       session?.dispose();
       releaseWsSession(params.sessionId);

src/agents/pi-embedded-runner/wait-for-idle-before-flush.ts

@@ -4,6 +4,7 @@ type IdleAwareAgent = {
 
 type ToolResultFlushManager = {
   flushPendingToolResults?: (() => void) | undefined;
+  clearPendingToolResults?: (() => void) | undefined;
 };
 
 export const DEFAULT_WAIT_FOR_IDLE_TIMEOUT_MS = 30_000;
@@ -11,23 +12,27 @@ export const DEFAULT_WAIT_FOR_IDLE_TIMEOUT_MS = 30_000;
 async function waitForAgentIdleBestEffort(
   agent: IdleAwareAgent | null | undefined,
   timeoutMs: number,
-): Promise<void> {
+): Promise<boolean> {
   const waitForIdle = agent?.waitForIdle;
   if (typeof waitForIdle !== "function") {
-    return;
+    return false;
   }
 
+  const idleResolved = Symbol("idle");
+  const idleTimedOut = Symbol("timeout");
   let timeoutHandle: ReturnType<typeof setTimeout> | undefined;
   try {
-    await Promise.race([
-      waitForIdle.call(agent),
-      new Promise<void>((resolve) => {
-        timeoutHandle = setTimeout(resolve, timeoutMs);
+    const outcome = await Promise.race([
+      waitForIdle.call(agent).then(() => idleResolved),
+      new Promise<symbol>((resolve) => {
+        timeoutHandle = setTimeout(() => resolve(idleTimedOut), timeoutMs);
         timeoutHandle.unref?.();
       }),
     ]);
+    return outcome === idleTimedOut;
   } catch {
     // Best-effort during cleanup.
+    return false;
   } finally {
     if (timeoutHandle) {
       clearTimeout(timeoutHandle);
@@ -39,7 +44,15 @@ export async function flushPendingToolResultsAfterIdle(opts: {
   agent: IdleAwareAgent | null | undefined;
   sessionManager: ToolResultFlushManager | null | undefined;
   timeoutMs?: number;
+  clearPendingOnTimeout?: boolean;
 }): Promise<void> {
-  await waitForAgentIdleBestEffort(opts.agent, opts.timeoutMs ?? DEFAULT_WAIT_FOR_IDLE_TIMEOUT_MS);
+  const timedOut = await waitForAgentIdleBestEffort(
+    opts.agent,
+    opts.timeoutMs ?? DEFAULT_WAIT_FOR_IDLE_TIMEOUT_MS,
+  );
+  if (timedOut && opts.clearPendingOnTimeout && opts.sessionManager?.clearPendingToolResults) {
+    opts.sessionManager.clearPendingToolResults();
+    return;
+  }
   opts.sessionManager?.flushPendingToolResults?.();
 }