Add Soroban event ingestion idempotency key derived from txHash and ledger in src/services/eventProcessor.ts

[1nonlypiece]

Add Soroban event ingestion idempotency key derived from txHash and ledger in src/services/eventProcessor.ts

Description

src/services/eventProcessor.ts writes events to the processed_events table (db/migrations/20260225220000_create_processed_events.cjs) but does not derive the idempotency key from txHash:ledger:eventIndex, leaving duplicate-event detection brittle. Compute and persist a canonical key as a unique index so retries cannot insert duplicates.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• New Knex migration adding event_key text unique not null
• Backfill existing rows where possible
• Update src/services/eventProcessor.ts and src/services/eventParser.ts
• Add src/tests/eventProcessor.idempotency.test.ts
• Update docs/event-processing.md

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/event-key-idempotency
• Implement changes
  • Add migration and backfill script
  • Update processor and parser
  • Add tests and docs
• Test and commit
  • Run npm run migrate:latest && npm test
  • Include test output and notes

Example commit message

feat: canonical idempotency key for Soroban events

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[Chrisland58]

@Chrisland58 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi maintainer I will like to work on this issue

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