The per-package parity tests compare our derivation against fossil's for fixtures built in-test, so they only cover the shapes someone thought to build. Issue #184 -- a silent 100% loss of the ticket-change artifact shape (D,J,K,U,Z) -- passed that suite throughout and was found by an external benchmark cloning the real Fossil repository.

Add TestCloneCorpusParity, which builds a repository with the canonical binary, serves it over loopback, clones it with both fossil and libfossil.Clone, and compares what each derived.

The comparison is per-event-type, not just totals. On the real Fossil repository the totals read 23,396 vs 27,099 -- a 14% shortfall that reads like rounding -- while the per-type breakdown put ticket events at 96 vs 3,808. Totals for blob, event, mlink, plink, tagxref and leaf are compared too, with deltas reported in both directions: our tagxref ran +17,119 over fossil's there, which is what writing a tag without finishing the work it marks looks like.

The corpus is built by the canonical binary at test time rather than downloaded -- seconds and under a megabyte, against the ~10 minutes and ~1 GB the real repository costs (#187) -- and covers check-ins with a branch and a merge, ticket creations and updates, a wiki page, a technote, an attachment, and a tag control artifact. requireCorpusShapes classifies every blob by its card set and fails if a shape falls below its floor, so a corpus that quietly stopped producing tickets cannot let the gate pass while covering nothing.

Gated behind LIBFOSSIL_CORPUS_PARITY=1 in addition to the existing fossil binary requirement, so the default suite is unchanged in runtime and outcome.

The gate fails on this commit, which is correct: #184 is unfixed, and it also surfaces a second divergence where a merged branch tip is missing from leaf.

Forum posts are not covered -- fossil exposes no CLI to create them. check-in: d01b94f4c1 user: [email protected] tags: trunk