`npm run build 2>&1 | tail -3` threw away npm's exit status, so a failed
build was indistinguishable from a good one. The run continued and blamed
the next check instead — "the frontend build no-opped or its output is
stale" — which points at a stale dist rather than at the build error that
actually happened, and cost a diagnosis cycle today.
Success still prints the same quiet 3 lines; a failure now prints the real
error, keeps the full log, and aborts on the spot.
Verified both branches with a stubbed npm.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
