fix(tool-pair-validator): skip placeholder repair for subagent sessions#4032
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code-yeongyu merged 1 commit intoMay 15, 2026
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Guard the tool-pair validator when transformed assistant messages belong to a tracked subagent session, while keeping normal main-session orphaned tool_use repair intact. Constraint: code-yeongyu#3996 reports background Oracle sessions hanging after synthetic placeholder tool_result insertion. Rejected: disable tool-pair-validator globally | would regress main-session compaction/orphaned tool_use repair. Confidence: high Scope-risk: narrow Directive: Keep subagent skip coverage and normal repair coverage together when changing tool-pair validation. Tested: bun test src/hooks/tool-pair-validator/hook.test.ts src/plugin/messages-transform.test.ts Tested: bun run typecheck Not-tested: live Oracle background task e2e; no remote push or PR comment performed.
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No issues found across 2 files
Confidence score: 5/5
- Automated review surfaced no issues in the provided summaries.
- No files require special attention.
Auto-approved: The change is narrowly scoped to skip placeholder repair only when the session is a tracked subagent, the new helper and condition are correct, existing tests pass, and a regression test covers both the skip and the unchanged main-session path, so there is no risk of regressions.
This was referenced May 15, 2026
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Summary
tool-pair-validatorhook inserts a synthetic placeholder tool_result when an assistant message contains an orphan tool_use. This is the right behavior for the main session (compaction can strip tool_results), but it corrupts background sub-agent sessions where the orphan is expected and the synthetic placeholder breaks downstream consumers.Changes
src/hooks/tool-pair-validator/hook.ts: read the session id from the transformed message via a smallgetMessageSessionIDhelper; bail out ofrepairMissingToolResultsif the session is tracked insubagentSessions. Import the registry fromsrc/features/claude-code-session-state.src/hooks/tool-pair-validator/hook.test.ts: new regression test asserting that a transformed assistant message owned by a tracked subagent session is left untouched, plus the existing main-session repair coverage stays green.Rationale (from commit body)
Testing
Not tested end-to-end against a live Oracle background task — that would need a real session reproduction, which I don't have a deterministic setup for. The unit coverage exercises both the subagent-skip path and the main-session repair path.
Related Issues
Closes #3996