fix(server): Claude subagents from a closed process no longer stay running

[id0Sch]

Problem

On Orchestrator V2 with Claude, a background task started in an earlier turn stays "Running" in Lineage forever once the Claude process is replaced (Stop/interrupt, or a model change after Stop). The agent can't stop it either, because from Claude's side the task no longer exists.

Observed on a real thread: turn 13 published an artifact, which auto-armed a monitor_ws "live updates for artifact" task (task_started, ambient: true). During turn 14 the user pressed Stop: query.interrupt → query.close → query.open with resume. The turn-14 subagent was cascaded to interrupted by its run's terminal, but the turn-13 one never got a task_notification (its process was gone) and its projection row stayed status: running, completedAt: null for 45+ minutes until a server restart.

#14726 already records these as subagentsFromEarlierProcesses ("their process is gone and never reports their end"), but only uses that to keep them from blocking a model change. They stay running in the projection and in the session registry, which also keeps hasPendingBackgroundWork true and so stops idle release.

Same symptom as #16355, different cause (that one is a lost completion for a nested subagent). Related area: #16000, #16073.

Fix

When a turn starts on a new process, interrupt the subagents the earlier process left running, via the existing updateClaudeSubagentNode path. The update keeps the subagent's original runId, so it reaches the launching run's ingestion (which stays open while that child is active) and lets that run settle. A subagent whose task_notification is already in the wake buffer is skipped, so it still completes when the buffer drains. updateClaudeSubagentNode now accepts interrupted, which the subagent, node and turn-item schemas already allow.

If the replacement process fails to open, no process of the session is left, so the same cleanup runs right there for every subagent still running, with the same buffered-completion exemption.

One limit: cleanup runs on the next turn, not at the moment of the interrupt, so if nothing is sent after Stop the row stays until the next message (or a server restart, where recovery already cancels it).

Verification

• Extended the existing "refuses a model change that would kill a running background subagent" test, which already runs this exact sequence (background subagent → Stop → new process). It now asserts the subagent's last update is interrupted in its launch run.
  • Without the fix: Timed out waiting for stopped subagent interrupted.
  • With the fix: vp test run apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts → 143 passed.
• New test "interrupts a stopped subagent when the replacement process fails to open" (Stop, then a model change whose open fails). Without the open-failure cleanup: Timed out waiting for orphaned subagent interrupted. With it: 227 passed.
• apps/server typecheck clean.
• Not checked in a live client: the stuck state came from real provider logs and projection rows on my machine, and the fix was verified through the adapter test.

Done by Claude Opus 5.5 (1M context) in Claude Code, driven from T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at f34ebbd

Macroscope's review found this PR approvable — This is a localized Claude process-lifecycle bug fix that cleans up orphaned subagent state during process replacement or failed reopen, with regression coverage for both paths. Existing live-process behavior and product defaults remain unchanged.

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📥 Commits

Reviewing files that changed from the base of the PR and between fb59d45 and f34ebbd.

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📒 Files selected for processing (2)

• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts
• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts

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🚧 Files skipped from review as they are similar to previous changes (2)

• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts
• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts

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📝 Walkthrough

📝 Walkthrough

📝 Walkthrough

📝 Walkthrough

Walkthrough

The Claude adapter interrupts eligible running subagents from a closed process after replacement query setup or when opening the replacement query fails. Tests verify the interrupted status and preservation of each subagent’s original run ID.

Changes

Claude subagent lifecycle

Layer / File(s)	Summary
Interrupt subagents from replaced processes apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts, apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts	The adapter accepts the interrupted status and interrupts eligible running subagents from closed processes after query setup or when opening a replacement query fails. It skips subagents with buffered task notifications. Tests check the interrupted status and preserved run ID, including when replacement query opening fails.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

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Merge Risk: ⚪ Minimal · up to f34eb

The change interrupts stale Claude subagents left over from a closed process, so they no longer block idle release. Tests cover both the replacement and the open-failure paths. No actionable merge-blocking risk remains.

Security Architecture Review

Security architecture risk: 🔵 Low · up to fb59d

The change improves cleanup of background work while preserving its original ownership. No new access path or broader permissions were identified, but recovery during failure and concurrent completion is not fully established.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The added operation reaches eligible entries in the existing provider-session registry, including running entries captured across native threads sharing that session. The inspected change does not introduce a global task selector, new external call, or broader tool authority.

Trust Boundaries and Controls

• observed — Original run attribution remains an event-routing control: reconciliation preserves task.runId rather than assigning the replacement run, and consumers require matching run ownership or an owned child-thread relationship.

Resilience and Maintainability Implications

• inferred — A failed replacement can retain running registry entries because reconciliation follows successful open and the open-error handler clears only wake and process-background state. This gap predates the PR. Failed-start cleanup clears busy-turn activity, and idle release has a configurable pin limit, defaulting to four hours, so indefinite session retention is not established.

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Pre-merge checks | 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title is concise, uses the repository's conventional format, and accurately describes the fix for Claude subagents left running after process replacement.
Description check		The description clearly covers the problem, implementation, verification results, limitations, and test evidence. It references related issues but does not explicitly provide a triage or maintainer-ap…

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at
@apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts:
- Line 8513: In the replacement-open failure handler in openQuery, interrupt
inherited subagents before clearing wake state. Use the old query context and
its lastTurn, only when both are available, and call
interruptSubagentsFromEarlierProcesses so buffered completions remain exempt and
the existing runId is preserved.

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📒 Files selected for processing (2)

• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts
• apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts

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