With the header checks merged, the library refuses truncated files and misaligned chunk-index keys itself, so check reported only "file cannot be opened" for a truncated file. It now reports the truncation (stored end of file vs file length) or the library's error, and the misaligned chunk test accepts the library's refusal of the key. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>