[Infra] Indexer event-processing failures are only logged - no failed-event counter in /health or admin metrics

[grantfox-oss]

Telegram (ask questions / claim the issue here first): https://t.me/+DOylgFv1jyJlNzM0

Why this matters

soroban-event-worker.ts:247-253 swallows per-event errors with logger.error and continues; there is no eventsProcessed/eventsFailed counter. /health only reports DB status and indexer lag (which stays low because the upsert bumps updatedAt every poll), and admin metrics report only lastLedger/lagSeconds. So an indexer silently dropping every event looks perfectly healthy.

Acceptance criteria

• Maintain eventsProcessed / eventsFailed / lastErrorAt counters in the worker
• Expose them in GET /v1/admin/metrics.indexer and consider a degraded signal when failures spike
• Cover the new counters with a unit test

Files to touch

• backend/src/workers/soroban-event-worker.ts
• backend/src/routes/v1/admin.routes.ts
• backend/src/routes/health.routes.ts

Out of scope

• Adding a Prometheus exposition format endpoint

[teeschima]

@teeschima has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, i would like to work on this issue

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[Queenode]

@Queenode has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue . I understand the assignment and the requirements, and I’m confident in the approach needed to deliver the best solution. Kindly assign this task to me.

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[grantfox-oss]

🦊 GrantFox — @Queenode has been assigned to this issue!

Next steps:

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