feat(metrics): count Redis webhook dedup hits (#2075)

[james3773]

Summary

• Add isWebhookDeliveryDuplicate and rememberWebhookDelivery in src/selfhost/redis-cache.ts to emit gittensory_webhook_dedup_total{backend="redis"} on Redis-backed webhook redelivery hits
• Wire the self-host webhook handler through those helpers; Redis errors fail open without incrementing
• Unit tests cover first-time delivery, dedup hit, and Redis-error paths

Closes #2075

Test plan

• npm run test -- test/unit/selfhost-redis-cache.test.ts
• npm run selfhost:env-reference:check (no UI/env-reference drift)
• Full npm run test:ci (9323/9324 passed; one unrelated flaky timeout in ai-summaries.test.ts)

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⏸️ Gittensory review result - manual review recommended

_{Review updated: 2026-07-05 16:40:04 UTC}

3 files · 1 AI reviewer · no blockers · readiness 80/100 · CI green · clean

⏸️ Suggested Action - Manual Review

• Touches a guarded path — held for manual review: This PR changes guardrail-protected path(s): src/selfhost/redis-cache.ts (matched src/selfhost/**).

Review summary
This PR adds `isWebhookDeliveryDuplicate` and `rememberWebhookDelivery` helpers in redis-cache.ts to encapsulate the existing delivery-ID dedup cache lookup/write, and wires them into server.ts's webhook handler so a dedup hit increments `gittensory_webhook_dedup_total{backend="redis"}` while Redis errors still fail open (return false / skip the metric) exactly as before. The change preserves the original control flow (204 on dedup hit, best-effort write on success) and adds a labeled seed value in the metrics-seeding loop so the series appears from first scrape. Tests cover first-time delivery, dedup hit with metric assertion, and the Redis-error fail-open path, which matches the actual behavior in the diff.

Nits — 6 non-blocking

• src/selfhost/redis-cache.ts: `rememberWebhookDelivery` already swallows errors internally via try/catch, so the caller's `.catch(() => undefined)` in server.ts is redundant belt-and-suspenders — fine to leave but worth a comment noting it's intentional double-safety.
• src/selfhost/redis-cache.ts:32: the `ttlSeconds = 300` default duplicates the previous inline magic number without a named constant explaining the 5-minute choice (matches GitHub's webhook retry window, per the module comment) — consider hoisting to a constant for discoverability.
• Adding the `backend="redis"` label changes the metric's label set from unlabeled to labeled; confirm any existing Grafana panel or alert on `gittensory_webhook_dedup_total` (unlabeled) is updated to match, since mixing labeled/unlabeled samples for the same metric name is invalid in Prometheus.
• Consider adding a short unit test asserting the seeded zero-value series `gittensory_webhook_dedup_total{backend="redis"} 0` appears at boot (server.ts's seeding loop change) so the first-scrape guarantee has explicit coverage.
• webhookDeliveryCacheKey is a small pure helper — fine as-is, but if a future in-memory backend needs the same dedup+metric pattern, extracting a backend-agnostic wrapper now would avoid duplicating this logic later.
• 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	✅ Linked	#2075
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	❌ 5/25	Preflight is holding this PR: the review lane is unavailable, so it is not ready for automated review.
Contributor workload	✅ 10/10	Author activity: 1054 registered-repo PR(s), 728 merged, 41 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	jony376; Gittensor profile; 1054 PR(s), 41 issue(s).
Gate result	⚠️ Not blocking	Advisory; not blocking this PR.

Review context

• Author: jony376
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository registration is not available in the local Gittensory cache.
• Public profile languages: TypeScript, Python, JavaScript, Rust, MDX, Clojure, Cuda, Dart
• Official Gittensor activity: 1054 PR(s), 41 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Await review-lane availability.
• Refresh registry data or choose a registered active repo.

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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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.09%. Comparing base (eb8cb4f) to head (a1807f6).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3544   +/-   ##
=======================================
  Coverage   93.09%   93.09%           
=======================================
  Files         301      301           
  Lines       31450    31462   +12     
  Branches    11483    11484    +1     
=======================================
+ Hits        29279    29291   +12     
  Misses       1517     1517           
  Partials      654      654           

Files with missing lines	Coverage Δ
src/selfhost/redis-cache.ts	100.00% <100.00%> (ø)

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