test(offline): e2e hotseat flow + fix $state-proxy persist

Add the Playwright mock e2e for offline pass-and-play (Chromium+WebKit):
create a 2-seat hotseat with a PIN-locked seat, verify the rack is
withheld, unlock (wrong then right PIN), host-skip the current turn, and
terminate from the lobby behind the master PIN.

The e2e surfaced a persistence bug: the roster PINs are $state proxies,
which fail structured-clone on the IndexedDB put (silently — best-effort
store), so a created hotseat game vanished on reload. Snapshot the seats
+ host PIN to plain objects at the create() call site.

ui/e2e/hotseat.spec.ts

@@ -0,0 +1,102 @@
+import { test, expect, type Page } from './fixtures';
+
+// Offline pass-and-play (hotseat) is offered only in offline mode, which is gated to an installed
+// standalone PWA with a confirmed email. The mock account has an email; force standalone so the
+// Settings offline toggle shows.
+async function forceStandalone(page: Page): Promise<void> {
+  await page.addInitScript(() => {
+    const orig = window.matchMedia.bind(window);
+    window.matchMedia = (q: string) =>
+      (q.includes('display-mode: standalone')
+        ? { matches: true, media: q, onchange: null, addEventListener() {}, removeEventListener() {}, addListener() {}, removeListener() {}, dispatchEvent: () => false }
+        : orig(q)) as MediaQueryList;
+  });
+}
+
+async function enterLobby(page: Page): Promise<void> {
+  await page.getByRole('button', { name: /guest|гост/i }).first().click();
+  await expect(page.locator('button.tab').nth(2)).toBeVisible();
+}
+
+async function goOffline(page: Page): Promise<void> {
+  await page.locator('button.tab').nth(2).click(); // Settings
+  await page.getByRole('button', { name: /^(Offline|Оффлайн)$/ }).click();
+  await expect(page.locator('header.nav.offline')).toBeVisible({ timeout: 15000 });
+  await page.getByRole('button', { name: /Back|Назад/i }).click();
+  await expect(page.locator('button.tab').nth(2)).toBeVisible();
+}
+
+// typePin clicks the on-screen keypad digits (the pad has no OK button — the 4th digit is the action).
+async function typePin(page: Page, digits: string): Promise<void> {
+  for (const d of digits) await page.locator('.pad .key', { hasText: d }).click();
+}
+
+test.describe('offline hotseat (pass-and-play)', () => {
+  test('create with a locked seat, unlock, host-skip, terminate from the lobby', async ({ page }) => {
+    await forceStandalone(page);
+    await page.goto('/');
+    await enterLobby(page);
+    await goOffline(page);
+
+    // A known bag seed so the locked seat deals a full rack deterministically.
+    await page.evaluate(() => (window as unknown as { __mock: { setLocalSeed(s: string): void } }).__mock.setLocalSeed('1'));
+
+    // New game -> the offline mode selector now offers "with friends" (hotseat).
+    await page.locator('button.tab').nth(0).click();
+    await page.getByRole('button', { name: /With friends|друзьями/i }).click();
+
+    // The player rows are disabled until the mandatory host (master) PIN is set.
+    await expect(page.locator('.pname').first()).toBeDisabled();
+
+    // Set the host PIN (enter + confirm), then decline taking a seat.
+    await page.locator('.hostpin .plink').click();
+    await typePin(page, '9999');
+    await typePin(page, '9999');
+    await page.getByRole('button', { name: /^(No|Нет)$/ }).click();
+
+    // Pick the English variant if the picker offers a choice.
+    const variant = page.locator('.fg select').first();
+    if (await variant.isEnabled()) await variant.selectOption('scrabble_en');
+
+    // Two players: Ann (PIN-locked) and Bob (open).
+    await page.locator('.pname').nth(0).fill('Ann');
+    await page.locator('.pname').nth(1).fill('Bob');
+    await page.locator('.prow').nth(0).locator('.plink').click(); // Ann's seat PIN
+    await typePin(page, '1234');
+    await typePin(page, '1234');
+
+    await page.locator('button.invite').click();
+    await expect(page.locator('[data-cell]').first()).toBeVisible();
+
+    // Ann is to move and PIN-locked: the board is visible but her rack is withheld behind Unlock.
+    await expect(page.locator('.unlock')).toBeVisible();
+    await expect(page.locator('.rack .tile')).toHaveCount(0);
+
+    // A wrong PIN keeps it locked; the right PIN reveals the full rack.
+    await page.locator('.unlock').click();
+    await typePin(page, '0000');
+    await expect(page.locator('.pad')).toBeVisible(); // still open after a wrong PIN
+    await typePin(page, '1234');
+    await expect(page.locator('.rack .tile')).toHaveCount(7);
+
+    // Host override: 🔐 -> master PIN -> skip the current turn -> confirm. The turn passes to Bob,
+    // whose seat is open, so his rack shows without a lock.
+    await page.locator('button.tab', { hasText: /Host|Ведущий/ }).click();
+    await typePin(page, '9999');
+    await page.getByRole('button', { name: /Skip|Пропустить/ }).click();
+    await page.getByRole('button', { name: /^(OK|ОК)$/ }).click();
+    await expect(page.locator('.unlock')).toHaveCount(0);
+    await expect(page.locator('.rack .tile')).toHaveCount(7);
+
+    // Back in the lobby the active hotseat game has a kebab; terminating it needs the master PIN.
+    await page.getByRole('button', { name: /Back|Назад/i }).click();
+    await expect(page.getByText('Ann', { exact: false }).first()).toBeVisible();
+    await expect(page.locator('.rowwrap')).toHaveCount(1);
+    await page.locator('.kebab').first().click();
+    const del = page.locator('.rowwrap.revealed .del');
+    await expect(del).toBeVisible();
+    await del.click();
+    await typePin(page, '9999');
+    await expect(page.locator('.rowwrap')).toHaveCount(0);
+  });
+});

ui/src/screens/NewGame.svelte

@@ -230,15 +230,18 @@
         return;
       }
       const id = newLocalGameId();
+      // Snapshot the roster + PINs to plain objects: the rows/pins are $state proxies, and a proxy
+      // fails structured-clone when the record is persisted to IndexedDB (silently, since the store
+      // is best-effort) — so the game would vanish on reload. See lib/localgame/store.
       await localSource.create({
         id,
         variant: inviteVariant,
         dictVersion: version,
         seed: randomSeed(),
         multipleWords: multipleWordsForRequest(inviteVariant, multipleWords),
-        seats: buildSeats(rows),
+        seats: $state.snapshot(buildSeats(rows)),
         hotseat: true,
-        hostPin,
+        hostPin: hostPin ? $state.snapshot(hostPin) : undefined,
       });
       navigate(`/game/${id}`);
     } catch (e) {