fix(server): Stop ends a dev server left running before a provider switch

[t3dotgg]

A thread started on Codex left vp run dev --share running, then moved to Claude. Clicking Stop on the "Running:" banner flashed "Stopping..." and then the button came back. The dev server kept running. The thread also did not auto-settle after its PR merged.

Stop. Stop only interrupted the latest run's provider thread (Claude). The cleanup step skips work that belongs to another provider session that is still alive, so the Codex dev server was never stopped. Now Stop also sends an interrupt to each other live provider thread that owns pending background work. Its existing settle follow-up ends what that provider leaves behind.

Auto-settle. Settlement refused any thread with background work. #15114 made a dev server left running stop counting as "waiting" in clients, but settlement still used the old rule. It now uses the same backgroundWorkHoldsCompletion rule: subagents and monitors still block settlement, a command left running does not.

Tests: a new integration test covers Stop after a provider switch, including work from several earlier runs and a native subagent (fails without the fix). The settlement tests cover a command left running.

Reviewed with sol-loop: 4 rounds with GPT-6.1-Sol on high.

🤖 Generated with Claude Code using Claude Opus 5.5.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The PR changes Stop and auto-settlement behavior across provider sessions, with meaningful process-lifecycle and concurrency effects beyond a simple local fix. Unresolved high-severity findings indicate that roster-only work, cleanup ordering, and active-run states may still leave background processes running.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ The exact PR base did not have a successful artifact. Baseline uses the latest successful main measurement shown below.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	4.9 KiB	4.9 KiB	+40 B (+0.8%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.7 KiB	3.7 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.1 KiB	1.2 KiB	+40 B (+3.4%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.4 KiB	20.4 KiB	+41 B (+0.2%)	29.3 KiB	✅
Codex	Live turn messages	1	2	+1 (+100.0%)	8	✅
Claude	Total thread wire	4.9 KiB	4.9 KiB	−41 B (−0.8%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.7 KiB	3.7 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	−41 B (−3.4%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	20.8 KiB	20.7 KiB	−41 B (−0.2%)	29.3 KiB	✅
Claude	Live turn messages	2	1	−1 (−50.0%)	8	✅

Baseline: 00eb8f6 · PR result: 60b0dfe · 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: 106.1 KiB
• Claude decoded thread snapshot: 106.4 KiB

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 79bda02 and 60b0dfe.

📒 Files selected for processing (4)

• apps/server/src/orchestration-v2/BackgroundWorkStop.integration.test.ts
• apps/server/src/orchestration-v2/EffectWorker.ts
• apps/server/src/orchestration-v2/Orchestrator.ts
• apps/server/src/orchestration-v2/ProjectionSettlement.test.ts

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📝 Walkthrough

Walkthrough

Auto-settlement now checks whether pending background work holds completion. Interrupt dispatch also schedules interrupts for eligible provider threads with pending background work. Tests cover settlement eligibility and interruption across provider threads.

Changes

Background work orchestration

Layer / File(s)	Summary
Background work settlement eligibility apps/server/src/orchestration-v2/ThreadSettlementService.ts, apps/server/src/orchestration-v2/ThreadSettlementService.test.ts, apps/server/src/orchestration-v2/ProjectionSettlement.test.ts	Auto-settlement now checks whether pending background work holds completion. Tests cover pending subagent and command tasks.
Interrupt pending-work provider threads apps/server/src/orchestration-v2/Orchestrator.ts, apps/server/src/orchestration-v2/EffectWorker.ts, apps/server/src/orchestration-v2/BackgroundWorkStop.integration.test.ts	Interrupt dispatch selects the latest pending turn per other provider thread with an active session. The integration test checks interrupts across provider threads and verifies that running commands and a native subagent are marked interrupted.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Orchestrator as dispatchRunInterrupt
  participant BackgroundWork as Pending background work
  participant ProviderSession as Active provider session
  participant ProviderThread as Provider thread turn
  Orchestrator->>BackgroundWork: Find pending work on other provider threads
  Orchestrator->>ProviderSession: Check for an active session
  ProviderSession-->>Orchestrator: Return session status
  Orchestrator->>ProviderThread: Schedule interrupt for selected turn

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Suggested reviewers: juliusmarminge

Merge Risk: 🟡 Moderate · up to 60b0d

Stop can still leave a command started by an earlier provider running when the latest run is active. This gap in the intended Stop behavior should be fixed before merging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the problem and changes, and it identifies relevant tests. It does not provide the required scope and approval information. It also does not state which checks were run or the…	Add a link to the triaged issue or maintainer discussion with explicit approval of the direction and scope. If this is an obvious-bug exemption, explain why it qualifies. State the focused checks you ran, their observed results, and anythin…

✅ Passed checks (4 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 6 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the Stop behavior that this change fixes: a dev server left running after a provider switch.

Full details: Description check

Explanation

The description explains the problem and changes, and it identifies relevant tests. It does not provide the required scope and approval information. It also does not state which checks were run or their observed results.

Resolution

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/server/src/orchestration-v2/Orchestrator.ts:
- Around line 8116-8118: Update the scan gate in the Stop flow to check whether
`run` is the latest run in `projection.runs`, rather than whether
`hasBackgroundWork` is true. This ensures the scan reaches earlier live provider
threads when the target is the active latest run, even if
`derivePendingBackgroundWork` returns no settled-work items.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository: pingdotgg/t3code/.coderabbit.yaml
• Review profile: CHILL
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• Run ID: 8ef0bcdf-0e65-4b2d-b9b2-9045a6b51a6a

📥 Commits

Reviewing files that changed from the base of the PR and between 8d84666 and 79bda02.

📒 Files selected for processing (4)

• apps/server/src/orchestration-v2/BackgroundWorkStop.integration.test.ts
• apps/server/src/orchestration-v2/Orchestrator.ts
• apps/server/src/orchestration-v2/ThreadSettlementService.test.ts
• apps/server/src/orchestration-v2/ThreadSettlementService.ts

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Dismissing prior approval to re-evaluate 60b0dfe