From 2cd5627fe85c3fd2785319084d4565e3fadcb24c Mon Sep 17 00:00:00 2001
From: Saqeb Akhter <saqeb.akhter@gmail.com>
Date: Tue, 3 Nov 2026 15:16:04 +0400
Subject: [PATCH] fix(assistants): ignore older background command completions
 (#42)

---
 src/assistant-turn-observer.ts  | 28 ++++++++++++++++++++-
 test/assistant-requests.test.ts | 43 +++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/src/assistant-turn-observer.ts b/src/assistant-turn-observer.ts
index 7419cd6ef..ffd75ccf7 100644
--- a/src/assistant-turn-observer.ts
+++ b/src/assistant-turn-observer.ts
@@ -7,6 +7,20 @@ export type TurnObservation =
   | { state: 'failed'; turnId: string; reason: string }
   | { state: 'unknown'; reason: string };
 
+/** Codex turn IDs encode their creation time as UUIDv7's first 48 bits.
+ * Only a strictly earlier timestamp proves a late background completion;
+ * unversioned IDs and IDs from the same millisecond remain ambiguous.
+ */
+function isEarlierCodexTurn(candidate: unknown, current: string): boolean {
+  const uuid7 = /^[0-9a-f]{8}-[0-9a-f]{4}-7[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+  return (
+    typeof candidate === 'string' &&
+    uuid7.test(candidate) &&
+    uuid7.test(current) &&
+    candidate.slice(0, 13).toLowerCase() < current.slice(0, 13).toLowerCase()
+  );
+}
+
 export function observeAssistantTurn(
   jsonl: string,
   conversationId: string,
@@ -30,7 +44,19 @@ export function observeAssistantTurn(
       : { state: 'waiting' };
   const turnId = starts[0].turn_id;
   if (typeof turnId !== 'string' || !turnId) return { state: 'unknown', reason: 'Unsupported native turn identity' };
-  const items = events.filter((p) => p.type === 'item_completed');
+  const startIndex = events.indexOf(starts[0]);
+  const items = events.filter((p, index) => {
+    if (p.type !== 'item_completed') return false;
+    // Background commands can finish after their parent turn completed, even
+    // during the next request. They are neither current-turn results nor
+    // evidence that a different conversation took control (#42).
+    const lateBackgroundCommand =
+      p.thread_id === conversationId &&
+      (p.item as { type?: string } | undefined)?.type === 'CommandExecution' &&
+      index > startIndex &&
+      isEarlierCodexTurn(p.turn_id, turnId);
+    return !lateBackgroundCommand;
+  });
   if (items.some((p) => p.turn_id !== turnId || p.thread_id !== conversationId))
     return { state: 'unknown', reason: 'Transcript identity changed' };
   const item = (p: Record<string, unknown>) =>
diff --git a/test/assistant-requests.test.ts b/test/assistant-requests.test.ts
index 97a56b0be..b2fe9a7b3 100644
--- a/test/assistant-requests.test.ts
+++ b/test/assistant-requests.test.ts
@@ -128,6 +128,49 @@ afterEach(async () => {
   rmSync(root, { recursive: true, force: true });
 });
 describe('durable assistant requests', () => {
+  it('completes once when an older background command finishes during this request (#42)', async () => {
+    const a = await ready();
+    const request = manager.submit(a, 'hello', 'late-background-command-42');
+    await manager.tick();
+    const id = '01a1a0ff-0bd4-71b2-b26f-33504a365079';
+    const records = turn('hello', 'current answer', id).trimEnd().split('\n');
+    const old = row({
+      type: 'item_completed',
+      thread_id: conversationId,
+      turn_id: '01a1a070-9999-70a1-b838-7e4162d35c0f',
+      item: { type: 'CommandExecution' },
+    });
+    appendFileSync(file, records.slice(0, 2).join('\n') + '\n' + old);
+    await manager.tick();
+    expect(manager.store.get(request.id)?.status).toBe('running');
+    appendFileSync(file, records.slice(2).join('\n') + '\n');
+    await manager.tick();
+    expect(manager.store.get(request.id)).toMatchObject({ status: 'completed', result: { text: 'current answer' } });
+    await manager.tick();
+    expect(writes).toEqual(['hello\r']);
+  });
+
+  it.each([
+    ['future command', '01a1a1ff-0bd4-71b2-b26f-33504a365079', 'CommandExecution', false],
+    ['same-millisecond command', '01a1a0ff-0bd4-71b2-b26f-33504a365078', 'CommandExecution', false],
+    ['unversioned command', 'older-turn', 'CommandExecution', false],
+    ['missing turn', undefined, 'CommandExecution', false],
+    ['old foreign conversation', '01a1a070-9999-70a1-b838-7e4162d35c0f', 'CommandExecution', true],
+    ['old user message', '01a1a070-9999-70a1-b838-7e4162d35c0f', 'UserMessage', false],
+    ['old final answer', '01a1a070-9999-70a1-b838-7e4162d35c0f', 'AgentMessage', false],
+  ])('still fails closed for %s', (_label, otherId, type, foreign) => {
+    const id = '01a1a0ff-0bd4-71b2-b26f-33504a365079';
+    const data =
+      turn('hello', 'current answer', id) +
+      row({
+        type: 'item_completed',
+        turn_id: otherId,
+        thread_id: foreign ? randomUUID() : conversationId,
+        item: { type },
+      });
+    expect(observeAssistantTurn(data, conversationId, 'hello')).toMatchObject({ state: 'unknown' });
+  });
+
   it('treats an exact empty native final as a stopped response failure, never unknown or task success', async () => {
     const a = await ready();
     const r = manager.submit(a, 'silent task', 'empty-native-123456789');