fix(provider-acp): Grok runs finish with their reply while background subagents keep working by juliusmarminge · Pull Request #17779 · pingdotgg/t3code

juliusmarminge · 2026-10-10T09:20:50Z

Fixes #17159, and the turn-stays-open half of #15489.

When a Grok turn spawned background subagents, the adapter kept the root turn open after session/prompt returned, until every subagent ended. If a subagent's model stream stalled, only Grok's own 3600 s idle timeout ended it. For up to an hour:

No waiting state. The thread showed a finished reply but still said "working", with no sign it was waiting on subagents.
Steering made it worse. Grok steers by interrupt-and-restart, so each steer marked the finished attempt superseded and folded it away. The new attempt replied and then held again.
Queued messages waited. They stayed queued behind the held run.

Fix

The run completes with its reply. Running subagents no longer hold a settled Grok root. They carry over past it through the mechanism that already handles subagents across an interrupt:
- a subagent's own tool calls and replies keep projecting into its child thread while no turn runs;
- the next turn picks up its open tool calls.
The rest falls out of that.
- Clients show the subagents as waiting background work, with Stop, the same way Claude's background work already shows.
- A follow-up starts a normal new turn instead of a steering restart, so nothing is superseded.
- Queued messages start at once.
- Stop still ends the subagents.
Unchanged: background commands and monitors still hold the turn. fix(server): Grok runs finish when background commands end in the turn #17144 changes how background commands release it and doesn't conflict with this.
Early child tool calls. Grok names a subagent's child session only in the Task result, after the child has already run. Its tool calls from before that were dropped; only its reply text waited. Tool calls now wait too, and replay in order once the session is known.
Scope: the new routing is limited to flavors that held a settled root for background work (deferFinalizeForBackgroundWork), which today is Grok only. Devin and Antigravity never held a root for a subagent and keep their current handling.

No stall timeout is added. A stalled subagent now sits in the waiting list with Stop instead of blocking the thread.

Tests

grok_background_subagent replay: extended so that, while the subagent is still running, it queues a message and sends a steer. It now checks:
- the pending-work list holds the subagent and no run is active;
- both messages start new runs and no attempt is superseded;
- the subagent's later tool call and reply land in its child thread;
- Grok's own reply after the subagent finishes still arrives as a continuation run.
On main it times out with run 1 stuck running and the queued run never starting. The extra Grok frames are hand-written from the recorded second-prompt exchange in message_steering, not a live recording.
grok_subagent_lineage replay: the server child now runs a tool before its Task result names its session. Without the fix the child thread has no tool row.
AcpAdapterV2.test.ts: 16 tests that relied on a subagent holding a settled root are converted; no assertions are dropped.
- Tests about carrying a subagent across an interrupt now interrupt a root that is still prompting.
- Tests about a settled-but-held root now hold it with a running monitor.
- The plain held-turn test now asserts the new behaviour: the turn completes and the subagent keeps running.
Suites run on the current head (main merged in, 2026-10-16):
- all replay fixtures (144);
- the Grok, Antigravity and acp-registry adapters and GrokProvider;
- provider-acp (109);
- typecheck for apps/server and provider-acp.
With the two source files reverted to main, both replays still fail as described above. In AcpAdapterV2.test.ts, 5 detached-process tests fail in my sandbox both with and without this change.

🤖 Generated with Claude Code (Opus 5.5)

…se reply finished A Grok turn that spawned background subagents stayed running after its reply until every subagent ended, because the deferred finalize counted running subagents as work that holds the root. A subagent whose model stream stalled held the run for Grok's 3600 s idle timeout. Meanwhile the thread showed plain "working", a follow-up became a steering restart that folded the finished reply as a superseded attempt, and queued messages waited behind it (#17159, the open-turn half of #15489). Subagents no longer hold the settled root. The run completes with its reply and the subagents carry over, as they already did across an interrupt. While no turn is active, a carried-over subagent's own session frames still project into its child thread through the settled turn, and the next turn adopts its open tool calls. Background commands and monitors keep their hold. With the run completed, the server's pending-work roster lists the subagent, so web, desktop and mobile show "Waiting on subagent ..." with Stop, a queued message starts at once, and a steer aimed at the finished run starts a new turn instead of superseding it. The grok_background_subagent replay now queues a message and steers while the subagent runs (hand-ported in the recorded Grok 1.0.41 frame shape), and checks the Waiting roster, that both start without superseding run 1, and that the subagent's later work still lands in its child thread. On main it times out with run 1 running and the queued run 2 queued. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…replay Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

A running subagent no longer holds a settled ACP root, so tests that waited for a settled-and-held root (afterPromptSettledWithBackgroundWork) with only a subagent never reached their interrupt. Those that cover carrying a subagent across an interrupt now keep the first prompt open (new T3_ACP_HOLD_FIRST_GENERIC_PROMPT_UNTIL_CANCEL mock flag) and interrupt it once the subagent is projected; their assertions are unchanged. The plain held-turn test now asserts the new behaviour: the turn completes with the subagent still running. The idle-carryover routing, open-tool adoption and the subagent-tool skip in root terminalization only apply to flavors that defer finalize for background work (Grok). Devin and Antigravity keep main's handling. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…onitor These tests cover interrupting a root whose prompt already settled and is held for background work. A subagent alone no longer holds it, so the mock now also leaves a background monitor running (T3_ACP_EMIT_RUNNING_MONITOR_WITH_GENERIC), which still does. Assertions are unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…ft tests A respawned runtime re-emitting the held monitor kept the next turn open. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…d with a monitor The finalization-window and in-turn-handled re-report tests need a root that is settled and still held when their subagent terminals arrive. A subagent alone no longer holds it, so a running monitor now does; the finalization-window test ends the monitor right after its first subagent so the finish debounce arms as before. Assertions are unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

macroscopeapp · 2026-10-10T09:22:47Z

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR materially changes production ACP turn lifecycle and background-subagent routing, including when Grok runs complete and how later messages and child-thread activity are handled. The accompanying tests are substantial, but the cross-turn state-management change and runtime blast radius merit human review.

No code changes detected at 3e22727. Prior analysis still applies.

^{You can add or adjust custom eligibility rules. Learn more.}

github-actions · 2026-10-10T09:24:22Z

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	+24 B (+0.5%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+24 B (+2.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	+41 B (+0.2%)	29.3 KiB	✅
Claude	Live turn messages	1	2	+1 (+100.0%)	8	✅

Baseline: 1550058 · PR result: 3e22727 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

Codex decoded thread snapshot: 108.5 KiB
Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

coderabbitai · 2026-10-10T09:29:13Z

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apps/server/src/orchestration-v2/Adapters/AcpAdapterV2.test.ts
packages/provider-acp/src/server/adapter.ts

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📝 Walkthrough

The adapter now allows root turns to complete while background subagents continue. It routes later subagent updates to child threads and carries eligible subagent state into later turns. Tests and fixtures cover queued and steered follow-ups, interruption, and carryover.

Changes: Background subagent lifecycle

Layer / File(s)	Summary
Root settlement and subagent state carryover `packages/provider-acp/src/server/adapter.ts`	Running subagents no longer hold root finalization open. The adapter retains settled-turn context and carries eligible notifications and tool state into later turns.
Child-session update routing `packages/provider-acp/src/server/adapter.ts`	The adapter buffers unassociated child-session notifications, routes associated updates to child threads, and excludes carried subagent tools from applicable root-turn terminalization.
Settlement and interruption tests `apps/server/scripts/acp-mock-agent.ts`, `apps/server/src/orchestration-v2/Adapters/AcpAdapterV2.test.ts`	Mock controls hold the first prompt until cancellation or emit a running monitor task. Tests cover root completion with a running subagent, interruption timing, independent monitor holds, and carryover.
Follow-up and child-thread fixture coverage `apps/server/src/orchestration-v2/testkit/fixtures/grok_background_subagent/`, `apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/`, `apps/server/src/orchestration-v2/testkit/fixtures/shared.ts`	Fixtures cover queued and steered prompts while a subagent continues. Assertions check run ordering, output placement, and a completed child tool call.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant RootTurn
  participant AcpAdapter
  participant ChildSession
  participant ChildThread
  participant NextTurn
  RootTurn->>AcpAdapter: Finalize while subagent continues
  ChildSession->>AcpAdapter: Send session updates
  AcpAdapter->>ChildThread: Buffer or project child updates
  NextTurn->>AcpAdapter: Adopt pending notifications and carried tool state

Suggested reviewers: t3dotgg

Merge Risk: ⚪ Minimal · up to 55f95

The reviewed change is mergeable after normal checks; no concrete remaining issue was established.

Pre-merge checks: 4

Check name	Status	Explanation
Linked Issues check		The PR meets the coding requirements in [`#17159`]. `adapter.ts` no longer treats running subagents as a reason to hold a settled root when `deferFinalizeForBackgroundWork` is enabled. Carryover project…
Out of Scope Changes check		The changed adapter code implements [`#17159`]. The Grok replay changes test settlement, waiting work, queued messages, steering, carryover, and child-thread routing. The lineage replay tests early chil…
Title check		The title is concise, specific, and accurately describes the primary change: Grok runs now finish while background subagents continue working.
Description check		The description explains the problem, the fix, scope boundaries, linked issues, verification coverage, known test limitations, and agent usage. It provides enough detail to satisfy the repository temp…

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🤖 Prompt to fix review comments

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Inline comments:
Review comments at @packages/provider-acp/src/server/adapter.ts:
- Around line 4338-4364: Update the carryover handling in startTurn to retain
carryoverSubagents and its buffered pendingSubagentNotifications when
requestedSessionId does not match; only clear them once the matching session
consumes them, or project the buffered notifications before clearing. Preserve
the existing behavior for matching sessions.
- Around line 4117-4225: Update handleSubagentSessionUpdate to buffer tool-call
notifications when no subagent association exists, rather than dropping them;
when the association is established, replay buffered notifications through
handleSubagentSessionUpdate so tool state is projected into the child thread.

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apps/server/scripts/acp-mock-agent.ts
apps/server/src/orchestration-v2/Adapters/AcpAdapterV2.test.ts
apps/server/src/orchestration-v2/testkit/fixtures/grok_background_subagent/grok_transcript.ndjson
apps/server/src/orchestration-v2/testkit/fixtures/grok_background_subagent/input.ts
apps/server/src/orchestration-v2/testkit/fixtures/grok_background_subagent/output.ts
apps/server/src/orchestration-v2/testkit/fixtures/shared.ts
packages/provider-acp/src/server/adapter.ts

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… named reach its child thread Grok's Task path names the child session only in its result, after the child already ran. Its assistant frames waited for that and replayed, but its tool_call/tool_call_update frames were dropped, so the child thread lost those calls. Both kinds now wait under the unknown session id and replay in order through the same subagent routing once the session is named. The grok_subagent_lineage replay now has the server child run a tool before its Task result; without this change the child thread has no dynamic_tool row. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/output.ts (1)
84-93: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Assert the exact child-thread item sequences.

assertTurnItemTypes checks only presence. It allows reordered items and extra items. The replay transcript adds the server child tool events between its progress and result, so enforce the documented sequences with assertTurnItemTypeSequence.

Retain assertTurnItemTypes for the parent assertion at line 36.
Proposed fix
  assertNoExtraAppRunsForProviderChildren,
+  assertTurnItemTypeSequence,
  assertTurnItemTypes,
...
-      assertTurnItemTypes(child, ["user_message", "assistant_message", "dynamic_tool"]);
+      assertTurnItemTypeSequence(child, ["user_message", "assistant_message", "dynamic_tool"]);
...
-      assertTurnItemTypes(child, ["user_message", "assistant_message"]);
+      assertTurnItemTypeSequence(child, ["user_message", "assistant_message"]);
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Review comment at
@apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/output.ts
around lines 84 - 93:
Update the child assertions in the lineage fixture to use
assertTurnItemTypeSequence instead of assertTurnItemTypes, enforcing exact order
and excluding extra items for both child cases. Retain assertTurnItemTypes for
the parent assertion.

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Nitpick comments:
Review comments at
@apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/output.ts:
- Around line 84-93: Update the child assertions in the lineage fixture to use
assertTurnItemTypeSequence instead of assertTurnItemTypes, enforcing exact order
and excluding extra items for both child cases. Retain assertTurnItemTypes for
the parent assertion.

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apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/grok_transcript.ndjson
apps/server/src/orchestration-v2/testkit/fixtures/grok_subagent_lineage/output.ts
packages/provider-acp/src/server/adapter.ts

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packages/provider-acp/src/server/adapter.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 8 remain after this review.

…r join Grok subagents cannot spawn subagents: Grok CLI 1.0.46's own docs say "Only the top-level session spawns subagents ... the maximum nesting depth is one. If a subagent calls spawn_subagent, the call fails with a depth-limit error." No Grok recording has a child-session spawn either. The idle-carryover block that added nested subagents to the carryover could never find one, so it is removed. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…em order The child-thread assertions only checked that each item type was present, so a reordered or extra row would still pass. They now assert the exact sequence, including the server child's early tool call after its reply. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

juliusmarminge and others added 6 commits October 10, 2026 01:32

test(server): narrow the Waiting roster's subagent entry in the Grok …

2588e17

…replay Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test(server): only the first ACP runtime holds the root in settled-so…

ba1f00a

…ft tests A respawned runtime re-emitting the held monitor kept the next turn open. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

github-actions Bot added vouch:trusted PR author is trusted by repo permissions or the VOUCHED list. size:L 100-499 changed lines (additions + deletions). labels Oct 10, 2026

juliusmarminge added the macroscope-review Opt PRs made by unvouched contributors in for Macroscope review. Vouched contributors auto-reviews label Oct 10, 2026

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juliusmarminge and others added 4 commits October 10, 2026 09:56

Merge origin/main into fix/grok-held-turns

55f95c4

Merge origin/main into fix/grok-held-turns

3e22727

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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fix(provider-acp): Grok runs finish with their reply while background subagents keep working - #17779

fix(provider-acp): Grok runs finish with their reply while background subagents keep working#17779
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