fix: resolve lock TTL, bad_seq detection, cache TTL, and FK cascade issues

[kris-nana]

Overview

This PR implements fixes for four medium-priority bugs affecting caching, error handling, database schema, and distributed locking.

Issues Resolved

Closes #237
Closes #238
Closes #239
Closes #240

Changes Implemented

1. Issue #239: Reward History Cache TTL

File: src/modules/rewards/reward.service.ts

• Increased reward history cache TTL from 30s to 300s
• Aligns with user profile cache duration
• Improves cache hit rate for rarely-changing data

2. Issue #240: FK Cascade

Files: src/database/schema.ts, src/database/migrations/0020_quiz_generated_for_cascade.sql

• Added onDelete cascade to generatedFor foreign key
• Created database migration
• Ensures consistency with other user-referencing FKs

3. Issue #237: Lock TTL

Files: src/utils/lock.ts, src/modules/rewards/reward.service.ts

• Increased default lock TTL from 30s to 60s
• Stellar operations use explicit 90s TTL
• Prevents lock expiration during network congestion

4. Issue #238: Bad Seq Detection

Files: src/stellar/transactions.ts, src/modules/rewards/reward.service.ts

• Added robust isBadSeqError helper function
• Checks HTTP response structure in addition to string matching
• Ensures compatibility across SDK versions

Testing

• All files compile without errors
• No breaking changes
• Database migration is idempotent

Deployment

1. Run migration before deploying code
2. All changes are backwards compatible
3. No API changes required

[drips-wave]

@kris-nana Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits