Lock the polish branch's behaviour so a future UI edit surfaces as a failing
assertion to re-agree or fix.
Unit (vitest, node env):
- placement: recallIndex, cellOccupied/isBlankSlot, non-linear direction, the
single-tile submit default, and placementFromHint blank-fallback / rack-exhausted.
- banner: the marquee scroll-cycle repeat-then-advance, stop(), root-relative and
multiple links.
- client.GatewayError. Extract the check-word constraints out of Game.svelte into a
pure lib/checkword.ts (sanitize + canCheck) and cover them.
E2E (playwright mock, Chromium + WebKit):
- commit via the 🏁 control, history slide-down + close, the exchange dialog,
check-word input sanitising + verdict, resign-to-finished, and the Settings
board-label mode changing the on-board labels.
Ilia Denisov