Public CI only runs synthetic fixtures, but every regression we have actually
shipped showed up on real projects, which are confidential and cannot reach a
GitHub runner. corpus_check.py runs a local corpus through the full pipeline
(parse, checks, HA YAML, entity suggestions) and diffs the counts against a
recorded baseline.
Only numbers are committed: counts, severity and code histograms, and a short
digest per source file. The project map with real paths lives in
tools/corpus_map.json, which is gitignored; corpus_map.example.json shows the
shape. Verified both directions: a deliberate change to the diagnostics filter
made the guard exit 1 and name the two metrics that moved, a clean tree exits 0,
and a machine without a map exits 2 without doing anything.
Wired into CONTRIBUTING and into the release checklist before the build step.
