Status on a checkout created by `fossil open` failed with "converting NULL to string" on vfile.mhash. go-libfossil treated mhash as every file's baseline hash; fossil only fills it while a merge is pending (the hash of mrid when mrid != rid) and judges a file against the blob that vfile.mrid names. A NULL-tolerant scan alone would not have fixed it: with no baseline the comparison panics, and skipping it would hide real edits.

ScanChanges now compares each file with blob.uuid for vfile.mrid and moves chnged through fossil's own transitions (vfile_check_signature): a pending add (mrid=0) becomes 1, unchanged and clean-merge states (0, 2, 4) become 1 on a difference, a reverted edit returns to 0, and other merge states are kept. Comparing against the artifact's own uuid also picks the hash algorithm per file, independent of hash-policy.

The non-forced Extract guard read mhash with its error discarded, so on a fossil checkout it skipped the check and overwrote local edits. It now uses the same baseline, propagates read errors, and refuses while a merge is pending (mrid != rid or chnged > 1).

Status and HasChanges treat a rename as origname not in ('', pathname), since fossil stores origname == pathname on unrenamed rows, and HasChanges now sees `fossil mv`. A malformed row returns an error instead of being reported as ChangeNone.

LoadVFile and Manage stop writing mhash, and Manage writes islink, which fossil's vfile schema declares without a default.

Tests drive real fossil-made checkouts: clean status, edits and adds, a pending merge (status, preserved merge state, extract refusal), local edits under extract, fossil mv, and a go-libfossil Add read back by both tools. check-in: 0069100efe user: [email protected] tags: trunk