Addresses P0 PR review test coverage requirements: Unit Tests (comment_service_test.go): - Fix mockUserRepo to implement GetByDIDs method (compilation blocker) - Update all buildCommentView calls to 4-parameter signature - Add 5 tests for GetByDIDs mock (empty, single, multiple, missing, fields) - Add 5 tests for JSON deserialization (facets, embeds, labels, malformed, nil/empty) - Total: 10 new unit tests covering Phase 2C functionality Integration Tests (user_test.go): - Add TestUserRepository_GetByDIDs with 7 comprehensive test cases - Test empty array, single/multiple DIDs, missing users, field preservation - Test validation: batch size limit (>1000), invalid DID format - All tests use real PostgreSQL database with migrations Test Fixes (comment_query_test.go): - Fix TestCommentQuery_InvalidInputs failing tests - Create real test post/community for validation tests - Tests now verify normalization works (negative depth, excessive limits) - All 6 test cases now pass Test Results: - Unit tests: 43 total (33 existing + 10 new) - ALL PASS - Integration tests: 26 total (19 comment + 7 user) - ALL PASS - Zero compilation errors, zero test failures Coverage validates: - Batch user loading prevents N+1 queries - Input validation rejects oversized/malformed inputs - JSON deserialization handles errors gracefully - Security validation prevents injection attacks 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>