Docs under frontend-modern/public/docs are byte-for-byte copies of repo
docs, but the only guard was a CI vitest the git hooks never run. On
2026-09-01 two commits (f4886c2dfb, f313882a7b) each edited a mirrored
doc without its copy, passed the hooks, and broke main's Frontend job.
Add scripts/check_docs_mirror.py with an index-blob --staged mode wired
into the pre-commit hook: a commit that stages either side of an
out-of-sync pair (or an orphan shipped copy) fails with the exact sync
command, while pre-existing drift from other commits only warns. The
worktree mode runs as a named step in the public-docs workflow, with
unit tests in scripts/tests picked up by the existing runner. The
docsLinks vitest stays as the CI backstop.
Build-time generation of public/docs was considered and rejected: the
shipped set is a curated subset (61 of 421 docs), so generation still
needs a hand-maintained manifest while adding build, dev-server, and
test-order coupling.
rcourtman
d28666c396