v1.3.0
Enforcement reaches the members. conventions/conventions-check is vendored beside the sync script and holds a repository's own Markdown to WRITING.md: American English and the spaced em-dash, with fenced and inline code left alone and any folder under exclude in conventions.json unread. .github/workflows/check.yml is a reusable workflow: one job named conventions that runs the sync check and the prose check, and refuses to run when the tag it is called at differs from the tag the repository pins.
The block in AGENTS.md names the new script, so every copy is stale; re-sync in the order REPOSITORIES.md gives. A member still on v1.2.0 runs sync twice the first time, because that script does not know about the file this release adds; from v1.3.0 on, one sync is enough. Two rules join WORKING.md: a branch is deleted once its pull request is merged, and every ruleset requires the conventions job.
To take it, from a repository's root, then add the workflow the README shows and require conventions in the ruleset:
printf '{ "repo": "robertblust/conventions", "tag": "v1.3.0" }\n' > conventions.json
curl -fsSL https://raw.githubusercontent.com/robertblust/conventions/v1.3.0/conventions/conventions-sync -o /tmp/conventions-sync
sh /tmp/conventions-sync sync