UI: fix last-move highlight, localize move history, clamp zoom overscroll

- Highlight tracks the last move overall (not the last word): a trailing
  pass/exchange now highlights nothing, so the board no longer lights up the
  opponent's old word after our own empty move.
- Make the highlight event-driven: refreshed only on a real game event
  (open/refresh, opponent move, our own committed move) and dismissed the moment
  composing starts, so recalling a just-placed tile never re-triggers it.
- Localize non-play move-history labels via new move.* catalog keys
  (pass/exchange/resign/timeout); the label printed the raw English action.
- Clamp the zoomed board's pan at its edge (overscroll-behavior: none), removing
  the native rubber-band past the content.

Tests: lastMoveCells unit coverage (trailing pass/exchange -> empty), i18n RU
label assertions, an e2e overscroll-contract check on the zoomed viewport.

ui/e2e/zoom.spec.ts

@@ -24,3 +24,31 @@ test('zoom enlarges the board labels with the board', async ({ page }) => {
   const zoomed = await letter.evaluate((el) => parseFloat(getComputedStyle(el).fontSize));
   expect(zoomed).toBeGreaterThan(base * 1.4);
 });
+
+// Item 4 (UX): the zoomed board clamps at its edge — no native rubber-band/overscroll past
+// the content. We assert the CSS contract on the zoomed scroll container, which is
+// deterministic across engines (the bounce gesture itself is a native compositor behaviour
+// Playwright cannot reliably synthesize).
+test('zoomed board clamps overscroll at the edge', async ({ page }) => {
+  await page.goto('/');
+  await page.getByRole('button', { name: /guest/i }).click();
+  await page.getByRole('button', { name: /Ann/ }).click();
+
+  // Double-tap an empty cell to zoom in.
+  await page
+    .locator('[data-cell]:not(.filled)')
+    .nth(20)
+    .evaluate((el: HTMLElement) => {
+      el.click();
+      el.click();
+    });
+
+  const viewport = page.locator('.viewport.zoomed');
+  await expect(viewport).toBeVisible();
+  const ob = await viewport.evaluate((el) => {
+    const s = getComputedStyle(el);
+    return { x: s.overscrollBehaviorX, y: s.overscrollBehaviorY };
+  });
+  expect(ob.x).toBe('none');
+  expect(ob.y).toBe('none');
+});

ui/src/game/Board.svelte

@@ -228,6 +228,9 @@
   }
   .viewport.zoomed {
     overflow: auto;
+    /* Clamp the pan at the board edge: kill the native rubber-band/overscroll so the zoomed
+       board cannot be dragged past its content into empty space — it just stops at the edge. */
+    overscroll-behavior: none;
   }
   /* The query container is the (zoom-scaled) board, so cqw labels scale WITH the board
      — a magnifying-glass zoom. */

ui/src/game/Game.svelte

@@ -11,9 +11,9 @@
   import { app, handleError, showToast } from '../lib/app.svelte';
   import { connection } from '../lib/connection.svelte';
   import { GatewayError } from '../lib/client';
-  import { t } from '../lib/i18n/index.svelte';
+  import { t, type MessageKey } from '../lib/i18n/index.svelte';
   import type { Direction, EvalResult, MoveRecord, MoveResult, StateView, Tile } from '../lib/model';
-  import { replay } from '../lib/board';
+  import { lastMoveCells, replay } from '../lib/board';
   import { centre, premiumGrid } from '../lib/premiums';
   import { variantNameKey } from '../lib/variants';
   import { alphabetLetters, hasAlphabet } from '../lib/alphabet';
@@ -68,27 +68,48 @@
         .map((p) => [`${p.row},${p.col}`, { letter: p.letter, blank: p.blank }]),
     ),
   );
-  const lastPlay = $derived([...moves].reverse().find((m) => m.action === 'play') ?? null);
-  // Highlight the last word with a dark tile bg; while placing, only the pending tiles
-  // are highlighted. It flashes when the opponent just moved and it is now our turn.
-  const highlight = $derived(
-    placement.pending.length > 0 || !lastPlay || (!!view && view.game.status !== 'active')
-      ? new Set<string>()
-      : new Set(lastPlay.tiles.map((tt) => `${tt.row},${tt.col}`)),
-  );
-  const flash = $derived(
-    !!lastPlay &&
-      !!view &&
-      view.game.status === 'active' &&
-      lastPlay.player !== view.seat &&
-      view.game.toMove === view.seat,
-  );
+  // The recent-move highlight tracks the LAST move overall (not the last word): a play
+  // highlights its tiles, a trailing pass/exchange shows nothing — so the board never lights
+  // up the opponent's old word after our own pass. It is event-driven (refreshRecent), set
+  // only on a real game event (open/refresh, opponent move, our own committed move) and
+  // dismissed the moment we start composing, so recalling a just-placed tile never
+  // re-triggers it. recentFlash plays the one-off flash when the opponent just moved and it
+  // is now our turn.
+  let recent = $state<Set<string>>(new Set());
+  let recentFlash = $state(false);
+  function refreshRecent() {
+    const v = view;
+    if (!v || v.game.status !== 'active') {
+      recent = new Set();
+      recentFlash = false;
+      return;
+    }
+    recent = lastMoveCells(moves);
+    const last = moves.length ? moves[moves.length - 1] : null;
+    recentFlash = !!last && last.action === 'play' && last.player !== v.seat && v.game.toMove === v.seat;
+  }
+  $effect(() => {
+    // Composing dismisses the highlight until the next event refreshes it (so recalling the
+    // tiles we just placed leaves the board cleared, not re-lit).
+    if (placement.pending.length > 0) {
+      recent = new Set();
+      recentFlash = false;
+    }
+  });
   const slots = $derived(rackView(placement));
   const rackSlots = $derived(slots.map((s) => ({ ...s, id: rackIds[s.index] ?? s.index })));
   const isMyTurn = $derived(!!view && view.game.status === 'active' && view.game.toMove === view.seat);
   const gameOver = $derived(!!view && view.game.status !== 'active');
   const bagEmpty = $derived((view?.bagLen ?? 0) === 0);
 
+  // moveActionLabel localizes a non-play move's history label (pass/exchange/resign/timeout);
+  // an unknown action (forward-compat for the MoveAction string union) falls back to its raw
+  // wire string.
+  const MOVE_LABELS = new Set(['pass', 'exchange', 'resign', 'timeout']);
+  function moveActionLabel(action: string): string {
+    return MOVE_LABELS.has(action) ? t(`move.${action}` as MessageKey) : action;
+  }
+
   async function load() {
     try {
       // Ask for the alphabet table only on a per-variant cache miss (the first open of a
@@ -105,6 +126,7 @@
       dirOverride = undefined;
       await applyDraft(st);
       recompute();
+      refreshRecent();
     } catch (e) {
       handleError(e);
     }
@@ -149,6 +171,7 @@
       moves = cached.moves;
       placement = newPlacement(cached.view.rack);
       rackIds = cached.view.rack.map((_, i) => i);
+      refreshRecent();
     }
     void load();
     void loadFriends();
@@ -167,6 +190,7 @@
       moves = res.cache.moves;
       setCachedGame(id, view, moves);
       recompute();
+      refreshRecent();
     } else if (res.refetch) {
       void load();
     }
@@ -482,6 +506,7 @@
     selected = null;
     dirOverride = undefined;
     recompute();
+    refreshRecent();
   }
 
   async function commit() {
@@ -725,7 +750,7 @@
             {#each moves as m, i (i)}
               <li>
                 <span class="hp">{view.game.seats[m.player]?.displayName ?? m.player}</span>
-                <span class="ha">{m.action === 'play' ? m.words.join(', ') : m.action}</span>
+                <span class="ha">{m.action === 'play' ? m.words.join(', ') : moveActionLabel(m.action)}</span>
                 <span class="hs">{m.score} <span class="ht">({m.total})</span></span>
               </li>
             {/each}
@@ -748,8 +773,8 @@
           {board}
           {premium}
           pending={pendingMap}
-          {highlight}
-          {flash}
+          highlight={recent}
+          flash={recentFlash}
           centre={ctr}
           {zoomed}
           {variant}

ui/src/lib/board.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { lastPlayTiles, replay } from './board';
+import { lastMoveCells, replay } from './board';
 import type { MoveRecord } from './model';
 
 function play(tiles: { row: number; col: number; letter: string; blank: boolean }[]): MoveRecord {
@@ -17,18 +17,11 @@ function play(tiles: { row: number; col: number; letter: string; blank: boolean
   };
 }
 
-const pass: MoveRecord = {
-  player: 1,
-  action: 'pass',
-  dir: '',
-  mainRow: 0,
-  mainCol: 0,
-  tiles: [],
-  words: [],
-  count: 0,
-  score: 0,
-  total: 0,
-};
+function simple(action: 'pass' | 'exchange'): MoveRecord {
+  return { player: 1, action, dir: '', mainRow: 0, mainCol: 0, tiles: [], words: [], count: 0, score: 0, total: 0 };
+}
+
+const pass = simple('pass');
 
 describe('board replay', () => {
   it('places play tiles and ignores non-play moves', () => {
@@ -48,10 +41,31 @@ describe('board replay', () => {
     expect(b.length).toBe(15);
     expect(b[0].length).toBe(15);
   });
+});
 
-  it('lastPlayTiles returns the most recent play, skipping passes', () => {
+describe('lastMoveCells', () => {
+  it('returns the last move cells when the last move is a play', () => {
+    const moves = [
+      pass,
+      play([
+        { row: 7, col: 7, letter: 'A', blank: false },
+        { row: 7, col: 8, letter: 'B', blank: false },
+      ]),
+    ];
+    expect(lastMoveCells(moves)).toEqual(new Set(['7,7', '7,8']));
+  });
+
+  it('highlights nothing when the last move is a pass after a play', () => {
     const moves = [play([{ row: 7, col: 7, letter: 'A', blank: false }]), pass];
-    expect(lastPlayTiles(moves)).toHaveLength(1);
-    expect(lastPlayTiles([pass])).toHaveLength(0);
+    expect(lastMoveCells(moves).size).toBe(0);
+  });
+
+  it('highlights nothing when the last move is an exchange', () => {
+    const moves = [play([{ row: 7, col: 7, letter: 'A', blank: false }]), simple('exchange')];
+    expect(lastMoveCells(moves).size).toBe(0);
+  });
+
+  it('highlights nothing for an empty journal', () => {
+    expect(lastMoveCells([]).size).toBe(0);
   });
 });

ui/src/lib/board.ts

@@ -3,7 +3,7 @@
 // the dictionary-independent history invariant (ARCHITECTURE §9.1): apply each play's
 // placed tiles onto an empty grid.
 
-import type { MoveRecord, Tile } from './model';
+import type { MoveRecord } from './model';
 import { BOARD_SIZE } from './premiums';
 
 export interface BoardCell {
@@ -36,10 +36,11 @@ export function replay(moves: MoveRecord[]): Board {
   return b;
 }
 
-/** lastPlayTiles returns the tiles of the most recent play (for highlighting). */
-export function lastPlayTiles(moves: MoveRecord[]): Tile[] {
-  for (let i = moves.length - 1; i >= 0; i--) {
-    if (moves[i].action === 'play') return moves[i].tiles;
-  }
-  return [];
+/** lastMoveCells returns the cells of the last move's tiles (as "row,col" keys), but only
+ * when that move placed tiles (a play). A trailing pass/exchange/resign/timeout highlights
+ * nothing — the recent-move highlight tracks the last move overall, not the last word. */
+export function lastMoveCells(moves: MoveRecord[]): Set<string> {
+  const last = moves.length ? moves[moves.length - 1] : null;
+  if (!last || last.action !== 'play') return new Set();
+  return new Set(last.tiles.map((t) => `${t.row},${t.col}`));
 }

ui/src/lib/i18n.test.ts

@@ -13,6 +13,12 @@ describe('i18n catalog', () => {
     expect(translate('ru', 'game.bag', { n: 7 })).toBe('7 в мешке');
   });
 
+  it('localizes move-history action labels', () => {
+    expect(translate('ru', 'move.exchange')).toBe('Обмен');
+    expect(translate('ru', 'move.pass')).toBe('Пас');
+    expect(translate('en', 'move.exchange')).toBe('Exchange');
+  });
+
   it('maps error codes to keys with a generic fallback', () => {
     expect(errorKey('not_your_turn')).toBe('error.not_your_turn');
     expect(errorKey('totally_unknown')).toBe('error.generic');

ui/src/lib/i18n/en.ts

@@ -88,6 +88,11 @@ export const en = {
   'game.noHintOptions': 'No options with your letters.',
   'game.scores': 'Scores: {n}',
 
+  'move.pass': 'Pass',
+  'move.exchange': 'Exchange',
+  'move.resign': 'Resigned',
+  'move.timeout': 'Timed out',
+
   'result.victory': 'Victory',
   'result.defeat': 'Defeat',
   'result.draw': 'Draw',

ui/src/lib/i18n/ru.ts

@@ -89,6 +89,11 @@ export const ru: Record<MessageKey, string> = {
   'game.noHintOptions': 'Нет вариантов с вашим набором.',
   'game.scores': 'Очков: {n}',
 
+  'move.pass': 'Пас',
+  'move.exchange': 'Обмен',
+  'move.resign': 'Сдача',
+  'move.timeout': 'Тайм-аут',
+
   'result.victory': 'Победа',
   'result.defeat': 'Поражение',
   'result.draw': 'Ничья',