The module system cut over on 2026-08-12 and website's `edge` branch was
deleted, so `ci/core-ref.json` named a branch that no longer exists.
The sha did not move. The pinned commit is an ancestor of `main`, the contract
is still MODULE_API_VERSION 1.5.0, and no chapter changed - this is a label
correction, not a re-pin, and deliberately not the moment d2 exists to create.
Nothing in CI reads the `branch` field: the workflow clones the repo and checks
out the sha, which is both why the cutover could not break the build and why a
wrong label here would have sat unnoticed indefinitely. The field is for the
person deciding whether a newer core is worth re-reading the book for, and a
branch that no longer exists tells them nothing. The `why` block now says which
half is load-bearing.
checkCoreApi.js's not-a-core error also asserted that core `main` "has none
until the cutover", which stopped being true at the same merge. A reader hitting
that message would have gone looking for a cutover that already happened - the
kit's own lesson from the CRLF defect, that a failure message naming a diagnosis
has to be right about it, applied to the kit's own scripts.
Verified both paths: the check still passes against a real core (^1.5.0 vs
1.5.0), and the rewritten message renders as intended. checkLinks,
checkRenameSites and checkChapterPaths all clean.
Co-Authored-By: Claude <noreply@anthropic.com>