A leftover checkout answering on 127.0.0.1:4173 satisfied the readiness probe,
so every acceptance flow and the recorded demo described another tree while the
build reported green. The builder now fails closed if the port already has a
listener, re-checks the spawned server after readiness, and verifies the served
app.js and src/domain.js bytes match the clone under test before the first gate.
Verified against a real stale tree: the occupied-port guard aborts, the
foreign-bytes guard aborts, and the matching tree still passes.
The import screen already states what it restored, and the migration notice
restated the same count, so the on-screen notice read as two stacked sentences
saying one thing. The notice now only describes the upgrade, and a unit test
fails if it starts restating the restored count again.
mercury