feat(queue): back per-PR transient locks with SubmissionLock DO (#8896)

[andriypolanski]

Summary

• Closes feat(queue): replace the best-effort transient-lock PR mutex with the documented SubmissionLock Durable Object #8896
• Adds SubmissionLock Durable Object (src/queue/submission-lock.ts) with wrangler binding SUBMISSION_LOCK and migration tag v2-submission-lock.
• claimTransientLock / releaseTransientLockIfOwner prefer the DO when bound; self-host without Durable Objects keeps the existing transient-cache mutex unchanged.
• Tests: concurrent DO claims (only one wins), cache fallback exclusivity, fail-open / TTL / ownership-release paths.

Scope

• The PR title follows type(scope): short summary Conventional Commit format, for example fix(api): restore profile access checks.
• This PR is focused and does not mix unrelated backend, UI, MCP, docs, dependency, and deploy changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• I linked a currently open issue this PR resolves (e.g. Closes #123) — a linked open issue is required for every contributor PR.

Validation

• git diff --check
• npm run cf-typegen (committed worker-configuration.d.ts)
• npx vitest run test/unit/transient-locks.test.ts — 19 passed; CI-scoped simulation (npm run build:miner not required for src/**) with --changed=origin/main --coverage.all=false --coverage: 100% patch lines (44/44) and 100% patch branches (40/40) on changed src/queue/** hunks
• npm run actionlint
• npm run typecheck
• npm run test:coverage
• npm run test:workers
• npm audit --audit-level=moderate
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries

If any required check was skipped, explain why:

Full test:ci left for the opener before push; targeted unit coverage above covers the DO, preference wiring, and cache fallback deliverables.

Notes for reviewers / gate

• No secrets, wallets, hotkeys, trust scores, or reward values.
• Does not touch site/, CNAME, **/lovable/**, or CHANGELOG.md.
• Self-host: SUBMISSION_LOCK unset → byte-identical cache lock behavior.
• Hosted: new DO migration tag v2-submission-lock (additive; RateLimiter v1-rate-limiter unchanged).

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.85%. Comparing base (8a3d2c9) to head (4b08e32).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8924   +/-   ##
=======================================
  Coverage   93.84%   93.85%           
=======================================
  Files         803      804    +1     
  Lines       80084    80128   +44     
  Branches    24277    24293   +16     
=======================================
+ Hits        75157    75201   +44     
  Misses       3562     3562           
  Partials     1365     1365           

Flag	Coverage Δ
backend	95.13% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/index.ts	96.26% <ø> (ø)
src/queue/processors.ts	95.71% <ø> (ø)
src/queue/submission-lock.ts	100.00% <100.00%> (ø)
src/queue/transient-locks.ts	100.00% <100.00%> (ø)

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-26 13:56:05 UTC}

11 files · 1 AI reviewer · no blockers · readiness 93/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This PR replaces the previously-deferred TODO with a real SubmissionLock Durable Object: claimTransientLock/releaseTransientLockIfOwner now prefer the DO (per-key idFromName serialization via the DO input gate) and fall through to the existing cache mutex when SUBMISSION_LOCK is unbound, preserving the documented fail-open posture end-to-end. Wiring is complete across the surfaces that matter — wrangler.jsonc/wrangler.vitest.jsonc bindings + a contiguous v2-submission-lock migration tag, env.d.ts, src/index.ts export, the self-host DurableObject shim, worker-configuration.d.ts regen, and the env-reference generator's injected-binding allowlist. The DO's own claim/release logic (owner-token compare-and-delete, TTL expiry, same-token refresh) is correct and exercised by concurrent-claim, ownership-release, TTL, and malformed-body tests, plus explicit DO-transport-failure and cache-fallback tests for claimTransientLock/releaseTransientLockIfOwner.

Nits — 5 non-blocking

• src/queue/transient-locks.ts:94/113 — the literal DO fetch URL host "submission-lock" is duplicated between claim and release; pull it into a shared constant.
• src/queue/submission-lock.ts — the claim/release HTTP status codes (400/404) are unlabeled magic numbers; naming them would help future readers, though this is purely stylistic for a DO-internal contract.
• src/queue/transient-locks.ts:releaseSubmissionLockIfBound ignores the DO fetch's response body/status entirely (even on success) — fine given the documented best-effort/TTL-backstop posture, but worth a one-line comment noting that's deliberate, not an oversight.
• Consider extracting the submission-lock fetch base URL/path constants in src/queue/transient-locks.ts to avoid the string duplication flagged above.
• If a later PR wants observability into DO release failures, log the caught error in releaseSubmissionLockIfBound instead of silently swallowing it, matching the pattern used elsewhere in this file.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#8896
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 199 registered-repo PR(s), 124 merged, 22 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	andriypolanski; Gittensor profile; 199 PR(s), 22 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: significant

Linked issue satisfaction

Addressed
The PR adds a SubmissionLock Durable Object with its own migration tag, wires claimTransientLock/releaseTransientLockIfOwner to prefer it while falling back to the cache mutex, and includes tests for concurrent DO claims (only one wins) and cache-fallback behavior for self-host installs.

Review context

• Author: andriypolanski
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: not available
• Official Gittensor activity: 199 PR(s), 22 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Triage stale or unlinked PRs.

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.

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

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[loopover-orb]

LoopOver approves — the gate is satisfied and CI is green.