An S-bearing manifest carries its files in sub-manifests, not in its own F run, so reading bare .f found none of them and every tracked path was classified `added` -- identical output whether or not anything had changed. Issue #25.

CheckinBaseline and DiffBaselineResolver now flatten first, the same step commit already performs. §5.1's "downstream MUST NOT distinguish" is exactly this: a raw .f read is how a reader opts out of the derivation seam.

Submanifest-specific, confirmed both ways: a --no-submanifests import was already clean. Not import-specific though -- any tree-shaped checkout hits it, so a clone from a tree-emitting peer would too.

Regression test asserts clean status and empty diff after materializing a tree check-in, and that a real edit still reports `edited`. check-in: 1e8c8a198d user: dmestas tags: sub-manifest