# Interview — Indexer & Durable Cursor

**Q: What is the main failure mode?**

A: RPC scanner can crash between writing block events and checkpointing.

**Q: How do you mitigate it?**

A: Persist events and cursor in one atomic database transaction; rescan safely after restart.

**Q: Is this demo production-ready?**

A: No. It illustrates an invariant in memory; production requires durable storage, retries, monitoring, security, and integration tests.