The migration (renamed from the provisional v1.64.0.0 slot, which open
PR #2564 claims) deleted only the poisoned .app while Playwright's
INSTALLATION_COMPLETE marker survived in the revision dir — so the
advertised 'bunx playwright install chromium' re-fetch no-opped and the
user finished the upgrade with no browser and a success message. Now:
the whole chromium-<rev> dir goes, bunx runs cwd-pinned to the install
root, .done is gated on a verified executable, and a needs-refetch
sentinel makes re-runs retry a failed download. Stranded rev dirs
(markers without .app) also re-trigger. 6 hermetic tests, red-first.
Garry Tan