11 tests covering: HTML serving with injected server URL, /api/progress
state reporting, submit → done lifecycle, regenerate → regenerating state,
remix with remixSpec, malformed JSON rejection, /api/reload HTML swapping,
missing file validation, and full regenerate → reload → submit round-trip.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Garry Tan