[Milestone 5] Production Hardening & Documentation

[Patrick-Ehimen]

Parent Issue #34

Goal

Make the system resilient to real-world conditions and produce comprehensive documentation.

Tasks

• Reorg detection (track block hashes, verify parent hash continuity, rewind cursor on fork)
• Backfill CLI: indexer backfill --chain=1 --protocol=layerzero --from=X --to=Y
• RPC failover: multiple endpoints per chain, automatic switchover
• Structured logging via zerolog
• Prometheus metrics (indexed_blocks_total, indexed_messages_total, rpc_request_duration_seconds, etc.)
• Scheduled O3 archival with Snappy-compressed Parquet and checksum verification
• O3 read-back for historical queries beyond hot storage window
• Documentation: Architecture Overview, Setup Guide, API Reference, Protocol Addition Guide, Data Schema Reference
• CI pipeline: lint → unit tests → integration tests → Docker build
• Test coverage target: >70% overall, >85% for decoders

Acceptance Criteria

• Reorg detected and handled correctly — no stale or duplicate messages
• Backfill indexes a block range idempotently
• RPC failover works without data loss
• Docs sufficient for a new developer to set up, run, and extend the project