feat(review): add a public weekly review-accuracy trend (#4447)

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Summary

• Extends GET /v1/public/stats with accuracyTrend: 8 trailing weeks of the SAME reversal-grounded formula the live totals.accuracyPct already uses (1 - reversed/(merged+closed)), so the trend and the live headline number can never silently diverge into two competing definitions of "accuracy".
• Deliberately not a cron/rollup table, despite the parent issue's text describing one: audit_events, pull_requests, and orb_pr_outcomes are already durable, so a live day-bucketed re-query of those same rows (folded into weekly buckets) can recompute any historical week correctly on every request — no cron-miss gap risk, and no second copy of the number that could drift out of sync with the live one. This mirrors the sibling per-repo quality trend already shipped in public-quality-metrics.ts (feat(site): add a public per-repo review-quality leaderboard #2568), which solves the exact same "public weekly trend from durable historical rows" problem the same way.
• A week with fewer than MIN_ACCURACY_TREND_SAMPLE decided PRs reports accuracyPct: null rather than a misleading percentage (mirrors the sibling trend's own MIN_GATE_TREND_SAMPLE guard).
• New src/services/public-accuracy-trend.ts: a pure buildPublicAccuracyTrend (bucketing/guard logic) plus an I/O loadPublicAccuracyTrend (day-bucketed SQL over the same three tables getPublicStats already reads). Composed at the route layer (not inside getPublicStats itself) to avoid a circular import between the two modules.
• Part of epic Epic: public, tracked-over-time benchmarks for gittensory's own review engine (speed, accuracy trend, efficiency) #4445's feat(stats): review-accuracy as a historical trend, not just a live snapshot #4447. Only the homepage trend-chart visualization the issue also describes is deferred to a follow-up PR, matching the capture-then-extend split already used for the epic's feat(stats): review turnaround-time tracking (webhook received → comment posted), public + historical #4446 slice (PR #4635).

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• 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.
• Advances feat(stats): review-accuracy as a historical trend, not just a live snapshot #4447 (part of epic Epic: public, tracked-over-time benchmarks for gittensory's own review engine (speed, accuracy trend, efficiency) #4445) — a partial slice (the frontend chart follows separately), so this does not close the issue.

Validation

• git diff --check
• npm run actionlint
• npm run typecheck
• npm run test:coverage locally — 100% line/branch coverage on src/services/public-accuracy-trend.ts (28/28 branches); the 2 pre-existing uncovered branches reported for src/review/public-stats.ts predate this diff (my only change there is exporting 3 already-covered declarations) and are outside this PR's changed lines
• npm run test:workers
• npm run build:mcp
• npm run test:mcp-pack
• npm run ui:openapi:check
• npm run ui:lint
• npm run ui:typecheck
• npm run ui:build
• npm audit --audit-level=moderate — 0 vulnerabilities
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries — pure-function tests (bucketing, MIN_SAMPLE guard, out-of-window/unparseable-day regressions, the reversed-exceeds-decided clamp) plus end-to-end integration tests seeding real audit_events/pull_requests/orb_pr_outcomes rows, plus a route-level shape assertion

Safety

• No secrets, wallet details, hotkeys, coldkeys, user PATs, private keys, raw trust scores, private rankings, or private maintainer evidence are exposed.
• Public GitHub text stays sanitized, low-noise, and does not imply compensation guarantees or optimization tactics.
• Auth, cookie, CORS, GitHub App, Cloudflare, or session changes include negative-path tests. — N/A, no auth/session surface touched.
• API/OpenAPI/MCP behavior is updated and tested where needed — PublicStatsSchema extended with accuracyTrend, regenerated via npm run ui:openapi, settings-parity checked.
• UI changes use live API data or real empty/error/loading states, not production mock/demo fallbacks. — N/A, backend-only change (no frontend chart in this slice).
• Visible UI changes include a UI Evidence section. — N/A, backend-only change, no visible UI.
• Public docs/changelogs are updated where needed. — N/A, no changelog edits in a normal PR; the trend has no public docs yet since there's no chart consuming it until the follow-up PR.

Notes

• Considered snapshotting computeGateEval (parity.ts) instead, per the issue's literal wording, but that reads only this worker's OWN review_audit ledger — it has no way to represent the registered Orb-fleet volume the live homepage number already folds in (getOrbGlobalStats), so building the trend from it would have made the trend a narrower, inconsistent subset of what the live number represents. Reusing the live number's own formula/scope avoids that regression.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	gittensory-ui	063cc59	Commit Preview URL Branch Preview URL	Jul 10 2026, 09:35 AM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.12%. Comparing base (bda42f7) to head (063cc59).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4655   +/-   ##
=======================================
  Coverage   94.11%   94.12%           
=======================================
  Files         433      434    +1     
  Lines       38494    38542   +48     
  Branches    14037    14047   +10     
=======================================
+ Hits        36229    36277   +48     
  Misses       1604     1604           
  Partials      661      661           

Files with missing lines	Coverage Δ
src/api/routes.ts	94.26% <100.00%> (ø)
src/openapi/schemas.ts	100.00% <ø> (ø)
src/review/public-stats.ts	96.66% <100.00%> (ø)
src/services/public-accuracy-trend.ts	100.00% <100.00%> (ø)

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