fix(orb): index orb_relay_pending.created_at to stop full table scans

[JSONbored]

Summary

orb-relay-drain's periodic pull-mode drain has been timing out since 2026-07-15 and is still recurring (Sentry orb_relay_drain/TimeoutError, 13+ occurrences, most recent within hours). Its handler unconditionally runs pruneRelayPending first on every 30s pull. That function issues a SELECT and a DELETE against orb_relay_pending filtered only by created_at — but both existing indexes on that table lead with installation_id, so neither query could use an index. Both fell back to a full table scan, fleet-wide, every 30 seconds, occasionally exceeding the pull request's own 30s timeout budget.

This adds the missing created_at index (migration 0167, mirrored in src/db/schema.ts) so both queries become index range scans instead.

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.

Closes #7430

Validation

• git diff --check
• npm run actionlint
• npm run typecheck
• npm run test:coverage locally — new regression test (test/unit/orb-relay-pending-created-at-index.test.ts) asserts EXPLAIN QUERY PLAN uses the new index (SEARCH, not SCAN) for both queries pruneRelayPending runs; npm run db:migrations:check and npm run db:schema-drift:check both clean (0167 confirmed as the next free migration number)
• 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
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries

If any required check was skipped, explain why:

• apps/loopover-ui's ui:test (vitest/jsdom) fails locally with window.localStorage undefined, on this sandbox's Node v26.5.0 (the repo pins Node 22 via .nvmrc, unavailable via nvm in this environment). Verified this reproduces identically on a clean, unmodified origin/main checkout with a fresh npm ci — it is a pre-existing local Node-version artifact unrelated to this change (which touches no apps/loopover-ui files), not a regression. Confirmed real GitHub Actions CI (validate-tests shards 1–6 + merge) is green on the exact main commit this branches from.

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/CORS surface touched.)
• API/OpenAPI/MCP behavior is updated and tested where needed. (N/A — no API/OpenAPI/MCP surface touched.)
• UI changes use live API data or real empty/error/loading states, not production mock/demo fallbacks. (N/A — no UI changes.)
• Visible UI changes include a UI Evidence section below with screenshots. (N/A — no visible UI change; this is a DB index + migration only.)
• Public docs/changelogs are updated where needed; changelogs are only edited for release-prep PRs. (N/A — internal query-plan fix, no user-facing behavior or doc change.)

Notes

• Root-caused via Sentry (orb_relay_drain) triage: pruneRelayPending's SELECT was added by a same-day commit on 2026-07-15, doubling the pre-existing unindexed DELETE's scan work — matching the exact day this Sentry issue started firing.

[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 91.35%. Comparing base (25decd9) to head (b0cc806).
⚠️ Report is 36 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7510   +/-   ##
=======================================
  Coverage   91.35%   91.35%           
=======================================
  Files         716      716           
  Lines       72990    72990           
  Branches    21628    21627    -1     
=======================================
  Hits        66678    66678           
  Misses       5272     5272           
  Partials     1040     1040           

Flag	Coverage Δ
shard-1	33.69% <ø> (+1.01%)	⬆️
shard-2	40.33% <ø> (+4.21%)	⬆️
shard-3	28.76% <ø> (-5.77%)	⬇️
shard-4	39.57% <ø> (-3.32%)	⬇️
shard-5	35.72% <ø> (-1.25%)	⬇️
shard-6	34.83% <ø> (+1.28%)	⬆️

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

Files with missing lines	Coverage Δ
src/db/schema.ts	72.97% <ø> (ø)