Adds 143 new tests across 5 files covering previously untested modules: - test_validators.py: all 7 validator functions + edge cases - test_hashing.py: content hash, duplicate detection - test_metadata_extraction.py: ComfyUI PNG metadata parsing with real images - test_config.py: GalleryConfig/PromptManagerConfig with mocked PromptServer - test_prompt_tracker.py: thread-safe prompt tracking, timeouts, context manager Total test count: 87 → 264