## Migration Decisions

- **Library**: `@isaacs/ttlcache` v2.1.4
- **Rationale**: Minimal, zero-dependency, specialized for TTL, well-maintained.
- **Cache Key**: Fixed string `'fingerprint'` since we only cache one result.
- **Max Items**: 1 (singleton fingerprint).
- **Default TTL**: 10 minutes (compatible with previous implementation).