- lib.rs: scan_images, compute_dhash, hamming, find_duplicate_groups - main.rs: CLI with folder arg and optional hamming threshold - 13 unit tests: hamming, is_image_path, dhash, find_duplicate_groups - 7 integration tests: real files, empty dir, cropped, non-image exclusion, subdirectory recursion, single file, CLI binary output - All 20 tests passing