- Create comprehensive test suite for PrismaService (10 tests) - Fix AppController tests with proper PrismaService mocking - Wrap seed operations in transaction for atomicity - Replace N+1 pattern with batch operations (createMany) - Add concurrency warning to seed script - All tests passing (14/14) - Build successful - Test coverage >85% Fixes #3 Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>