Make the chain indexer reorg-safe

[Lakes41]

Difficulty: Advanced

Type: Feature

Summary

Improve the membership event indexer so it handles chain reorganisations, finality windows, and duplicate event delivery safely.

Current Behaviour

The indexer can process membership events and persist progress, but simple last-block checkpointing can be unsafe if the chain reorganises after events have already been applied.

Expected Behaviour

The indexer should only finalise events after a configurable confirmation depth and should safely reconcile events if a reorg is detected.

Suggested Implementation

Add a configurable finality window. Store event block hash, block number, transaction hash, log index, and processed status. Re-scan recent blocks before advancing the finalised checkpoint.

Files or Areas Likely Affected

• apps/access-api/src/workers/
• apps/access-api/prisma/schema.prisma
• packages/contracts/src/index.ts
• apps/access-api/src/services/
• .env.example

Acceptance Criteria

• Indexer stores block hash and log identity for processed events
• Confirmation depth is configurable
• Recent blocks can be re-scanned safely
• Duplicate logs are ignored idempotently
• Reorg detection triggers safe reconciliation or retry
• Tests cover duplicate logs, re-scans, and changed block hashes

Additional Notes

This builds on the membership event indexer and focuses specifically on production chain safety.

[clintjeff2]

Hello, I have 6 years of experience working on tasks like this and handling similar challenges across backend, frontend, and smart-contract development. I have carefully read and fully understood the task requirements, and I am confident I can deliver a clean, efficient, and well-tested solution promptly. I always ensure high-quality implementation, maintainability, and adherence to best practices.

Pull request in 5 hours.

[grantfox-oss]

🦊 GrantFox — @clintjeff2 has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #52)
2. Your PR will be reviewed by the Adamantine-guild maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@clintjeff2's PR #75 was approved and merged by @Lakes41.

🏆 @clintjeff2: You earned 45 FoxPoints for this contribution! Your current tier: Specialist (5,396 total points). Track your full progress on GrantFox.

👏 Great work, @clintjeff2! Keep contributing to Adamantine-guild.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@clintjeff2's PR #76 was approved and merged by @Lakes41.

🏆 @clintjeff2: You earned 45 FoxPoints for this contribution! Your current tier: Specialist (5,936 total points). Track your full progress on GrantFox.

👏 Great work, @clintjeff2! Keep contributing to Adamantine-guild.