845 backend background indexer worker logs carry no correlation

[jotel-dev]

Description

Background Soroban event worker poll cycles and admin replays previously ran outside any requestContext, leaving worker log lines (including per-event error logs) without a shared correlation ID (requestId).

This PR wraps every worker poll cycle and admin replay batch in requestContext.run({ requestId: ... }, ...) via AsyncLocalStorage. All logs emitted within a cycle now share a unified requestId, and the correlation ID is returned in the response of the admin replay endpoint (POST /v1/admin/indexer/replay).

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 📚 Documentation update
• 🧪 Test addition or update

Related Issues

Closes #845

Changes Made

• backend/src/workers/soroban-event-worker.ts:
  • Wrapped scheduled poll() cycles and triggerPoll() in requestContext.run({ requestId }, ...).
  • Added fallback context binding inside fetchAndProcessEvents() to guarantee all RPC calls, event processing steps, and error logs carry the requestId.
• backend/src/services/indexerService.ts:
  • Updated replayFromLedger() to accept an optional customRequestId, bind execution inside requestContext, pass requestId to triggerPoll(), and return the requestId.
• backend/src/routes/v1/admin.routes.ts:
  • Updated POST /v1/admin/indexer/replay endpoint to return { ok: true, replayingFrom: ledger, requestId: "..." }.
• Documentation:
  • Added Logging & Observability sections to docs/ARCHITECTURE.md and backend/README.md.
• Tests:
  • Added backend/tests/worker-correlation-id.test.ts to test correlation ID binding across worker poll cycles and replay requests.

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

1. Run backend unit tests: npm test (all 51 test suites / 355 tests pass).
2. Trigger an admin replay via POST /v1/admin/indexer/replay?from_ledger=<ledger> and verify the HTTP response contains the requestId field.
3. Observe JSON log output during a poll cycle or replay to confirm all log lines share the corresponding requestId.

Breaking Changes

None.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

closes #845