A tracked file can be a complete check-in manifest -- a vendored fossil source tarball is the ordinary route, since fossil stopped sterilizing archive exports in 2.18. The import stores it verbatim rather than mutating it the way fossil's own git import does: the file the user committed should be the file we store, and open already refuses to materialize a check-in whose content is absent. But the operator should hear it at import, not at the first open, so such blobs are counted and reported. Two bytes reject ordinary content before anything is parsed.

The --manifest e2e now pins the marker's POSITION, not just its presence: it follows the final card and is not line 1. A refactor moving it to line 1 would still sterilize and would still pass every previous assertion, while silently diverging from fossil and breaking the mirror strip.

Errata for artifact-format 4.1.2 filed separately; the draft states the wrong position, the wrong rejection gate, and a literal no fossil code path emits. check-in: 12ce319d18 user: dmestas tags: sub-manifest