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Victor KuznetsovandClaude Opus 5
2668f1302d
Three gaps found while measuring the record path against the file path, each one a signal the library could not see: WebP stores `XMP ` after the pixels, so on any WebP above the scan window a fixed read stops short of the label. `_riff_late_metadata` steps over the coded image to reach it, the RIFF analogue of the existing PNG and ISOBMFF readers. Three corpus files hid an IPTC "Made with AI" tag and a C2PA `trainedAlgorithmicMedia` there. The decoder-backed fallback now covers only what it is actually for -- metadata the raw bytes do not spell, such as a compressed PNG `zTXt` packet. A C2PA reader failure returned the same `None` as a file with no manifest, so a verdict could fall back to the raw byte scan with no trace anywhere. Failures now log at warning and only genuine ones do: a file without credentials never reaches that branch, and an unsupported container is demoted to debug through the reader's own `C2paError.NotSupported`. The first corpus run with it found a truncated PNG. `scan_dataset.py` never registered the pillow-heif opener it declares as a dependency, so every HEIC was scanned as unreadable -- no EXIF, and a pixel layer that was 397 of 406 features NaN instead of 136. `_riff_late_metadata` caps its total like `isobmff.scan_c2pa_region` does. Clamping each chunk to the bytes remaining is not enough on its own: one chunk can declare a length spanning most of the file, and this runs on the memoized verdict path over images from arbitrary sources. Also lands `identify_metadata_record` and `ProvenanceReport.to_dict()`, the one-call entry point and the versioned JSON contract for the record path. Record-vs-file equality holds over 3,478 corpus images, and the eight files these fixes recovered still report AI. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>