fix(review): fail closed on sparse duplicate claims

[JSONbored]

Motivation

• Prevent sparse or invalid linkedIssueClaimedAt metadata from arbitrarily electing a low-number PR as the duplicate-winner via PR-number fallback, which can suppress duplicate evidence and alter gate/agent outcomes.
• Preserve integrity of duplicate-gate decisions by treating unknown/invalid claim-time ordering as a fail-closed condition so duplicate findings remain visible until claim-time ordering is known.

Description

• Change isDuplicateClusterWinnerByClaim so a null or unparsable linkedIssueClaimedAt on the subject PR or any open sibling returns false (fail closed) instead of falling back to isDuplicateClusterWinner by PR number, leaving tie-by-claim behavior intact for equal-known timestamps. (file: src/signals/duplicate-winner.ts)
• Update related call sites and explanatory comments to reflect that sparse legacy rows now fail closed, including advisory generation, agent maintenance wiring, and public panel text. (files: src/rules/advisory.ts, src/queue/processors.ts, src/signals/engine.ts)
• Refresh unit tests in test/unit/duplicate-winner.test.ts to assert that missing or invalid claim timestamps cause the cluster election to fail closed while preserving PR-number tie-break behavior for equal known timestamps.

Testing

• Ran targeted unit tests with vitest: test/unit/duplicate-winner.test.ts, test/unit/rules.test.ts, and test/unit/agent-actions.test.ts (pattern "dup-winner|duplicate risk|duplicate cause") and the selected tests passed.
• Ran typecheck with npm run typecheck which completed successfully.
• Attempted npm run test:coverage and npm audit --audit-level=moderate in this environment, but the full coverage run did not complete due to unrelated long-running test shards/timeouts and npm audit returned 403 Forbidden from the registry; these are environmental and unrelated to the focused unit/regression tests exercised above.

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Codex Task

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.62%. Comparing base (0924f23) to head (6148fad).
⚠️ Report is 18 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1843   +/-   ##
=======================================
  Coverage   95.62%   95.62%           
=======================================
  Files         214      214           
  Lines       23274    23274           
  Branches     8402     8404    +2     
=======================================
  Hits        22255    22255           
  Misses        422      422           
  Partials      597      597           

Files with missing lines	Coverage Δ
src/queue/processors.ts	88.27% <ø> (ø)
src/rules/advisory.ts	97.64% <ø> (ø)
src/signals/duplicate-winner.ts	100.00% <100.00%> (ø)
src/signals/engine.ts	97.34% <ø> (ø)

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Warning

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⏸️ Gittensory review result - manual review recommended

_{Review updated: 2026-06-30 08:30:30 UTC}

5 files · 1 AI reviewer · no blockers · readiness 80/100 · CI green · unknown

⏸️ Suggested Action - Manual Review

• Touches a guarded path — held for manual review

Review summary
The change makes duplicate-cluster winner election fail closed whenever the subject PR or any open sibling has missing/unparseable claim timing, and the visible call-site comment updates match that behavior. The core comparison still preserves the known-timestamp ordering and PR-number tie-break for equal known timestamps, so the changed logic is internally consistent. The notable remaining issue is documentation drift in the provided current context for the feature flag description, not a runtime defect in this diff.

Nits — 3 non-blocking

• nit: src/env.d.ts still documents GITTENSORY_DUPLICATE_WINNER as selecting the lowest open PR number, but this diff relies on earliest known linked-issue claim timing and fail-closed sparse rows.
• Update the GITTENSORY_DUPLICATE_WINNER comment in src/env.d.ts to match src/signals/duplicate-winner.ts, including the fail-closed behavior for missing or invalid linkedIssueClaimedAt values.
• Touches a guarded path — held for manual review — A maintainer must review and merge this change.

Signal	Result	Evidence
Code review	✅ No blockers	1 reviewer
Linked issue	✅ No-issue rationale	PR body explains why no issue is linked.
Related work	⚠️ 1 scoped overlap	Top overlaps are listed below; lower-confidence bulk is hidden.
Change scope	❌ 8/20	High review scope from cached public metadata (size label size:S; no linked issue context).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 2 registered-repo PR(s), 2 merged, 273 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	JSONbored; Gittensor profile; 2 PR(s), 273 issue(s).
Gate result	⚠️ Not blocking	Advisory; not blocking this PR.

Review context

• Author: JSONbored
• Role context: owner (maintainer lane)
• Public audience mode: oss maintainer
• Lane context: Repository registration is not available in the local Gittensory cache.
• Public profile languages: not available
• Official Gittensor activity: 2 PR(s), 273 issue(s).
• Related work: Titles/paths share 6 meaningful terms. (PR #1818)

Contributor next steps

• Treat this as maintainer-lane context rather than normal contributor-lane activity.
• Review top overlaps.
• Add a concise scope and risk note.
• No action.
• Link the issue being solved, or explicitly explain why this is a no-issue PR.
• Check active issues and PRs before submitting.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

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