gstack-update-check signals "up to date" with SILENCE, and it runs under
set -e — so any unguarded mid-script failure exited quietly and was
indistinguishable from a current install. Observed live as a 45-release
silent-staleness incident. An ERR trap (with -E so it propagates into
functions) now emits a CHECK_FAILED sentinel naming the line and status,
and exits 0 so caller `|| true` guards can't eat it. Behavioral tests cover
both the crash and the healthy-silent paths; egress-receipt wiring is
untouched and still pinned by test/egress-receipt-wiring.test.ts.
Fixes#1974. (#2378's HEAD-SHA staleness half was already fixed on main by
the ls-remote + SHA-pinned VERSION resolution — close as already-fixed.)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Garry Tan