[Richiey1]

Closes #14

Summary of Changes

Implemented cursor-aware pagination for the Soroban event fetcher and enforced true event-level idempotency to prevent duplicate domain writes across checkpoints.

What changed

• Replaced simplistic startLedger polling with cursor-based pagination in rpc.getEvents calls inside the indexer engine.
• Implemented stable cursor persistence to safely survive crashes midway through a ledger range page.
• Tracked processed events by unique event.id returned by Soroban RPC instead of just tx_hash.
• Replaced the TreasuryEvent database constraint from tx_hash to event_id to cleanly support multiple distinct treasury events emitted within a single transaction.

Testing / Local Verification

npm run build
npm run test:indexer
npm run lint

[diiabblo]

Review: Request Changes

Good direction -- cursor-based pagination and Redis-backed event idempotency are the right approaches. A few issues need fixing before merge:

Blocking

Missing migration for schema change (prisma/schema.prisma)
The TreasuryEvent model drops @unique from txHash and adds a new eventId unique field. No migration SQL is included. Add a prisma migrate dev --create-only migration that adds the event_id column with a unique index and safely removes the tx_hash unique constraint.

No tests
The issue requires tests for paginated responses, replay idempotency, crash recovery, and multiple events per transaction. The PR contains no test files.

Should address

(response as any).cursor (src/lib/indexer/engine.ts:347)
The SorobanRpc response type should include a cursor field. Use proper typing instead of any casting.

Redis Set grows unbounded
orbitpay:indexer:processed_events has no TTL. Add an expiry or periodic cleanup so this does not grow indefinitely as events accumulate.

[diiabblo]

great job @Richiey1