feat(mobile): implement mobile-first responsive design per §16.5

- Fix nav/home breakpoints from 768px → 639px to match design system
- Add leaderboard mobile card view with tap-to-expand stats and full-stats link
- Add canvas wrapper aspect-ratio:1 on phone (fills full width, square viewport)
- Add commentary text scroll on mobile, win-prob header stacking
- Replay viewer: mobile controls, pinch-to-zoom, tap-to-play, swipe scrub,
  floating view-mode toggle, debug telemetry slide-up sheet (already in place)
- Sandbox: desktop-required message with link already implemented

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/app.html

@@ -206,7 +206,7 @@
     }
 
     /* Responsive Navigation */
-    @media (max-width: 768px) {
+    @media (max-width: 639px) {
       .nav-container {
         height: 50px;
       }

web/src/pages/home.ts

@@ -511,11 +511,13 @@ export async function renderHomePage(): Promise<void> {
   padding: 16px 0;
 }
 
-/* Responsive */
-@media (max-width: 768px) {
+/* Responsive — phone (<640px) */
+@media (max-width: 639px) {
   .home-grid { grid-template-columns: 1fr; }
   .home-hero h1 { font-size: 1.75rem; }
   .home-tagline { font-size: 1rem; }
+  .home-hero { padding: 20px 16px; }
+  .home-ctas { flex-wrap: wrap; }
   .home-season {
     flex-direction: column;
     gap: 10px;
@@ -535,6 +537,7 @@ export async function renderHomePage(): Promise<void> {
     gap: 8px;
     align-items: flex-start;
   }
+  .home-pl-card { width: 140px; }
 }
 </style>`;
 }

web/src/pages/leaderboard.ts

@@ -18,7 +18,7 @@ export async function renderLeaderboardPage(): Promise<void> {
 
   try {
     const data = await fetchLeaderboard();
-    renderLeaderboardTable(content, data.entries, data.updated_at);
+    renderLeaderboard(content, data.entries, data.updated_at);
   } catch (error) {
     content.innerHTML = `
       <div class="error">
@@ -29,7 +29,7 @@ export async function renderLeaderboardPage(): Promise<void> {
   }
 }
 
-function renderLeaderboardTable(
+function renderLeaderboard(
   container: HTMLElement,
   entries: LeaderboardEntry[],
   updatedAt: string
@@ -47,22 +47,29 @@ function renderLeaderboardTable(
 
   container.innerHTML = `
     <p class="updated-at">Last updated: ${formatTimestamp(updatedAt)}</p>
-    <table class="leaderboard-table">
-      <thead>
-        <tr>
-          <th>Rank</th>
-          <th>Bot</th>
-          <th>Rating</th>
-          <th>W/L</th>
-          <th>Win Rate</th>
-          <th>Status</th>
-        </tr>
-      </thead>
-      <tbody>
-        ${entries.map(entry => renderLeaderboardRow(entry)).join('')}
-      </tbody>
-    </table>
+    <div class="table-container">
+      <table class="leaderboard-table">
+        <thead>
+          <tr>
+            <th>Rank</th>
+            <th>Bot</th>
+            <th>Rating</th>
+            <th>W/L</th>
+            <th>Win Rate</th>
+            <th>Status</th>
+          </tr>
+        </thead>
+        <tbody>
+          ${entries.map(entry => renderLeaderboardRow(entry)).join('')}
+        </tbody>
+      </table>
+    </div>
+    <div class="mobile-cards" role="list">
+      ${entries.map(entry => renderMobileCard(entry)).join('')}
+    </div>
   `;
+
+  initMobileCardToggles(container);
 }
 
 function renderLeaderboardRow(entry: LeaderboardEntry): string {
@@ -87,6 +94,54 @@ function renderLeaderboardRow(entry: LeaderboardEntry): string {
   `;
 }
 
+function renderMobileCard(entry: LeaderboardEntry): string {
+  const rankClass = entry.rank <= 3 ? `rank-${entry.rank}` : '';
+  const statusClass = entry.health_status === 'healthy' ? 'status-healthy' :
+                      entry.health_status === 'unhealthy' ? 'status-unhealthy' : 'status-unknown';
+  const winRate = entry.win_rate.toFixed(1);
+
+  return `
+    <div class="leaderboard-mobile-card" role="listitem" data-bot-id="${encodeURIComponent(entry.bot_id)}" aria-expanded="false">
+      <div class="leaderboard-mobile-rank ${rankClass}">${entry.rank}</div>
+      <div class="leaderboard-mobile-info">
+        <div class="leaderboard-mobile-name">${escapeHtml(entry.name)}</div>
+        <div class="leaderboard-mobile-rating">${entry.rating} <span style="opacity:.6;font-size:.8em">±${entry.rating_deviation}</span></div>
+      </div>
+      <div class="leaderboard-mobile-trend" aria-hidden="true">—</div>
+      <div class="leaderboard-mobile-details">
+        <div class="leaderboard-mobile-stat">
+          <span class="leaderboard-mobile-stat-label">W / L</span>
+          <span class="leaderboard-mobile-stat-value">${entry.matches_won} / ${entry.matches_played}</span>
+        </div>
+        <div class="leaderboard-mobile-stat">
+          <span class="leaderboard-mobile-stat-label">Win Rate</span>
+          <span class="leaderboard-mobile-stat-value">${winRate}%</span>
+        </div>
+        <div class="leaderboard-mobile-stat">
+          <span class="leaderboard-mobile-stat-label">Status</span>
+          <span class="leaderboard-mobile-stat-value ${statusClass}">${entry.health_status}</span>
+        </div>
+        <a href="#/bot/${encodeURIComponent(entry.bot_id)}"
+           class="btn small"
+           style="margin-top:10px;display:block;text-align:center"
+           aria-label="Full stats for ${escapeHtml(entry.name)}">Full Stats &rarr;</a>
+      </div>
+    </div>
+  `;
+}
+
+function initMobileCardToggles(container: HTMLElement): void {
+  container.querySelectorAll<HTMLElement>('.leaderboard-mobile-card').forEach(card => {
+    card.addEventListener('click', (e) => {
+      if ((e.target as HTMLElement).closest('a')) return;
+      const details = card.querySelector<HTMLElement>('.leaderboard-mobile-details');
+      if (!details) return;
+      const expanded = details.classList.toggle('expanded');
+      card.setAttribute('aria-expanded', String(expanded));
+    });
+  });
+}
+
 function formatTimestamp(iso: string): string {
   try {
     return new Date(iso).toLocaleString();

web/src/pages/replay.ts

@@ -33,9 +33,29 @@ function initReplayViewerWithClass(ReplayViewerClass: any, initialUrl?: string):
       <div class="replay-layout">
         <div class="replay-main">
           <div class="canvas-wrapper">
-            <canvas id="replay-canvas"></canvas>
+            <canvas id="replay-canvas" style="touch-action:none"></canvas>
             <div id="no-replay" class="no-replay-message">Load a replay file to view</div>
           </div>
+
+          <!-- Mobile compact controls bar — CSS hides on tablet+ -->
+          <div class="mobile-replay-controls" id="mobile-controls">
+            <div class="mobile-playback-bar">
+              <button id="mobile-reset-btn" class="btn small" aria-label="Reset to start" disabled>&#9612;&#9612;</button>
+              <button id="mobile-prev-btn" class="btn small" aria-label="Previous turn" disabled>&#9664;</button>
+              <button id="mobile-play-btn" class="btn small primary" aria-label="Play or pause" disabled>&#9654;</button>
+              <button id="mobile-next-btn" class="btn small" aria-label="Next turn" disabled>&#9654;&#9654;</button>
+              <span id="mobile-turn-info" class="mobile-speed-display">T: 0/0</span>
+              <button id="mobile-speed-btn" class="btn small secondary" aria-label="Cycle playback speed">100ms</button>
+            </div>
+            <input type="range" id="mobile-turn-slider" min="0" max="0" value="0"
+              style="width:100%;margin-top:4px" disabled aria-label="Turn scrubber">
+          </div>
+
+          <!-- Mobile event timeline ribbon — CSS hides on tablet+ -->
+          <div class="mobile-event-timeline" id="mobile-timeline" aria-label="Event timeline">
+            <span style="color:var(--text-muted);font-size:0.75rem;padding:4px 8px">Load a replay</span>
+          </div>
+
           <div id="win-prob-section" class="win-prob-section" style="display:none">
             <div class="win-prob-header">
               <span class="win-prob-title">Win Probability</span>
@@ -162,6 +182,10 @@ function initReplayViewerWithClass(ReplayViewerClass: any, initialUrl?: string):
       </div>
     </div>
 
+    <!-- Floating view mode toggle — CSS hides on tablet+desktop -->
+    <button id="mobile-view-mode-btn" class="mobile-view-mode-toggle"
+      aria-label="Switch view mode" title="Switch view mode">&#128065;</button>
+
     <!-- Debug telemetry bottom sheet (mobile) / sidebar panel (desktop) -->
     <div id="debug-panel" class="panel debug-panel" style="display:none">
       <div class="debug-panel-header" id="debug-panel-toggle-btn" role="button" tabindex="0"
@@ -332,11 +356,35 @@ function initReplayViewer(ReplayViewerClass: any, initialUrl?: string): void {
   const debugPlayerToggles = document.getElementById('debug-player-toggles') as HTMLDivElement;
   const debugInfoDisplay = document.getElementById('debug-info-display') as HTMLDivElement;
 
+  // Mobile controls
+  const mobilePlayBtn = document.getElementById('mobile-play-btn') as HTMLButtonElement;
+  const mobilePrevBtn = document.getElementById('mobile-prev-btn') as HTMLButtonElement;
+  const mobileNextBtn = document.getElementById('mobile-next-btn') as HTMLButtonElement;
+  const mobileResetBtn = document.getElementById('mobile-reset-btn') as HTMLButtonElement;
+  const mobileTurnInfo = document.getElementById('mobile-turn-info') as HTMLSpanElement;
+  const mobileTurnSlider = document.getElementById('mobile-turn-slider') as HTMLInputElement;
+  const mobileSpeedBtn = document.getElementById('mobile-speed-btn') as HTMLButtonElement;
+  const mobileTimeline = document.getElementById('mobile-timeline') as HTMLDivElement;
+  const mobileViewModeBtn = document.getElementById('mobile-view-mode-btn') as HTMLButtonElement;
+
   let viewer = new ReplayViewerClass(canvas, { cellSize: 10 });
   let criticalMoments: Array<{turn: number; delta: number; description: string}> = [];
   let commentaryEnabled = true;
   let debugPanelExpanded = false;
 
+  // Mobile speed cycling
+  const SPEED_STEPS = [1000, 500, 200, 100, 50, 20];
+  let mobileSpeedIdx = 3; // default 100ms
+
+  // View mode cycling
+  const VIEW_MODES: Array<'standard' | 'dots' | 'voronoi' | 'influence'> = ['standard', 'dots', 'voronoi', 'influence'];
+  const VIEW_MODE_ICONS: Record<string, string> = { standard: '\u{1F5FA}', dots: '··', voronoi: '⬡', influence: '◎' };
+
+  // Pinch-to-zoom pointer state
+  const activePointers = new Map<number, PointerEvent>();
+  let pinchStartDist = 0;
+  let pinchStartCellSize = 10;
+
   function enableControls(): void {
     playBtn.disabled = false;
     prevBtn.disabled = false;
@@ -346,6 +394,63 @@ function initReplayViewer(ReplayViewerClass: any, initialUrl?: string): void {
     noReplayDiv.style.display = 'none';
   }
 
+  function enableMobileControls(): void {
+    mobilePlayBtn.disabled = false;
+    mobilePrevBtn.disabled = false;
+    mobileNextBtn.disabled = false;
+    mobileResetBtn.disabled = false;
+    mobileTurnSlider.disabled = false;
+  }
+
+  function updateMobileUI(): void {
+    const turn = viewer.getTurn();
+    const total = viewer.getTotalTurns();
+    mobileTurnInfo.textContent = `T: ${turn}/${total - 1}`;
+    mobileTurnSlider.value = String(turn);
+    mobilePlayBtn.textContent = viewer.getIsPlaying() ? '⏸' : '▶';
+  }
+
+  function buildMobileTimeline(replay: Replay): void {
+    const eventTurns: number[] = [];
+    replay.turns.forEach((t: any, i: number) => {
+      if (t.events && t.events.length > 0) eventTurns.push(i);
+    });
+
+    if (eventTurns.length === 0) {
+      mobileTimeline.innerHTML = '<span style="color:var(--text-muted);font-size:0.75rem;padding:4px 8px">No events</span>';
+      return;
+    }
+
+    const currentTurn = viewer.getTurn();
+    mobileTimeline.innerHTML = eventTurns.map(turn => {
+      const active = turn === currentTurn ? ' active' : '';
+      return `<button class="mobile-event-dot${active}" data-turn="${turn}" aria-label="Turn ${turn}"><span style="font-size:0.65rem">${turn}</span></button>`;
+    }).join('');
+
+    mobileTimeline.querySelectorAll<HTMLElement>('.mobile-event-dot').forEach(dot => {
+      dot.addEventListener('click', () => {
+        const t = parseInt(dot.dataset.turn!, 10);
+        viewer.setTurn(t);
+        updateUI();
+        updateEventLog();
+        updateMobileUI();
+        updateMobileTimeline();
+      });
+    });
+  }
+
+  function updateMobileTimeline(): void {
+    const currentTurn = viewer.getTurn();
+    mobileTimeline.querySelectorAll<HTMLElement>('.mobile-event-dot').forEach(dot => {
+      const t = parseInt(dot.dataset.turn!, 10);
+      dot.classList.toggle('active', t === currentTurn);
+    });
+    const activeDot = mobileTimeline.querySelector<HTMLElement>('.mobile-event-dot.active');
+    if (activeDot) {
+      activeDot.scrollIntoView({ behavior: 'smooth', inline: 'center', block: 'nearest' });
+    }
+  }
+
   function updateUI(): void {
     turnDisplay.textContent = String(viewer.getTurn());
     totalTurnsSpan.textContent = String(viewer.getTotalTurns());
@@ -393,10 +498,14 @@ function initReplayViewer(ReplayViewerClass: any, initialUrl?: string): void {
   function loadReplay(replay: Replay): void {
     viewer.loadReplay(replay);
     enableControls();
+    enableMobileControls();
     updateMatchInfo(replay);
     turnSlider.max = String(viewer.getTotalTurns() - 1);
+    mobileTurnSlider.max = String(viewer.getTotalTurns() - 1);
     updateUI();
     updateEventLog();
+    updateMobileUI();
+    buildMobileTimeline(replay);
     initWinProb(replay);
     loadCommentary(replay.match_id);
     initDebugPanel(replay);
@@ -684,11 +793,16 @@ function initReplayViewer(ReplayViewerClass: any, initialUrl?: string): void {
     updateUI();
     updateEventLog();
     if (criticalMoments.length > 0) updateCriticalMomentNav();
+    updateMobileUI();
+    updateMobileTimeline();
   };
   viewer.onDebugChange = (debug: Record<number, DebugInfo> | null) => {
     updateDebugDisplay(debug);
   };
-  viewer.onPlayStateChange = (playing: boolean) => { playBtn.textContent = playing ? 'Pause' : 'Play'; };
+  viewer.onPlayStateChange = (playing: boolean) => {
+    playBtn.textContent = playing ? 'Pause' : 'Play';
+    mobilePlayBtn.textContent = playing ? '⏸' : '▶';
+  };
   viewer.onCommentaryChange = (entry: { turn: number; text: string; type: string } | null) => {
     if (!entry || !commentaryEnabled) {
       commentaryText.textContent = '';
@@ -698,6 +812,118 @@ function initReplayViewer(ReplayViewerClass: any, initialUrl?: string): void {
     commentaryText.className = `commentary-text type-${entry.type}`;
   };
 
+  // ── Mobile controls ─────────────────────────────────────────────────────────
+  mobilePlayBtn.addEventListener('click', () => viewer.togglePlay());
+  mobilePrevBtn.addEventListener('click', () => {
+    viewer.setTurn(viewer.getTurn() - 1);
+    updateUI(); updateEventLog(); updateMobileUI(); updateMobileTimeline();
+  });
+  mobileNextBtn.addEventListener('click', () => {
+    viewer.setTurn(viewer.getTurn() + 1);
+    updateUI(); updateEventLog(); updateMobileUI(); updateMobileTimeline();
+  });
+  mobileResetBtn.addEventListener('click', () => {
+    viewer.pause(); viewer.setTurn(0);
+    updateUI(); updateEventLog(); updateMobileUI(); updateMobileTimeline();
+  });
+  mobileTurnSlider.addEventListener('input', () => {
+    viewer.setTurn(parseInt(mobileTurnSlider.value, 10));
+    updateUI(); updateEventLog(); updateMobileUI(); updateMobileTimeline();
+  });
+  mobileSpeedBtn.addEventListener('click', () => {
+    mobileSpeedIdx = (mobileSpeedIdx + 1) % SPEED_STEPS.length;
+    const speed = SPEED_STEPS[mobileSpeedIdx];
+    viewer.setSpeed(speed);
+    speedDisplay.textContent = String(speed);
+    speedSlider.value = String(speed);
+    mobileSpeedBtn.textContent = `${speed}ms`;
+  });
+
+  // Floating view mode toggle
+  mobileViewModeBtn.addEventListener('click', () => {
+    const current = viewer.getViewMode();
+    const idx = VIEW_MODES.indexOf(current as any);
+    const next = VIEW_MODES[(idx + 1) % VIEW_MODES.length];
+    viewer.setViewMode(next);
+    mobileViewModeBtn.textContent = VIEW_MODE_ICONS[next] ?? '👁';
+  });
+
+  // ── Canvas touch gestures ────────────────────────────────────────────────────
+  // Tap = play/pause; horizontal swipe = prev/next turn; two-finger pinch = zoom
+
+  let tapStartX = 0;
+  let tapStartY = 0;
+  let tapStartTime = 0;
+
+  canvas.addEventListener('pointerdown', (e: PointerEvent) => {
+    activePointers.set(e.pointerId, e);
+    canvas.setPointerCapture(e.pointerId);
+
+    if (activePointers.size === 1) {
+      tapStartX = e.clientX;
+      tapStartY = e.clientY;
+      tapStartTime = Date.now();
+    } else if (activePointers.size === 2) {
+      const pts = [...activePointers.values()];
+      const dx = pts[0].clientX - pts[1].clientX;
+      const dy = pts[0].clientY - pts[1].clientY;
+      pinchStartDist = Math.sqrt(dx * dx + dy * dy);
+      pinchStartCellSize = viewer.getCellSize();
+    }
+  });
+
+  canvas.addEventListener('pointermove', (e: PointerEvent) => {
+    activePointers.set(e.pointerId, e);
+
+    if (activePointers.size === 2) {
+      const pts = [...activePointers.values()];
+      const dx = pts[0].clientX - pts[1].clientX;
+      const dy = pts[0].clientY - pts[1].clientY;
+      const dist = Math.sqrt(dx * dx + dy * dy);
+      if (pinchStartDist > 0) {
+        const newSize = Math.round(pinchStartCellSize * (dist / pinchStartDist));
+        viewer.setCellSize(newSize);
+      }
+    }
+  });
+
+  canvas.addEventListener('pointerup', (e: PointerEvent) => {
+    const wasOne = activePointers.size === 1;
+    const endX = e.clientX;
+    const endY = e.clientY;
+    activePointers.delete(e.pointerId);
+
+    if (wasOne) {
+      const dx = endX - tapStartX;
+      const dy = endY - tapStartY;
+      const elapsed = Date.now() - tapStartTime;
+      const dist = Math.sqrt(dx * dx + dy * dy);
+
+      if (elapsed < 300 && dist < 12) {
+        // Tap: play/pause
+        if (viewer.getReplay()) viewer.togglePlay();
+      } else if (elapsed < 500 && Math.abs(dx) > 40 && Math.abs(dy) < 50) {
+        // Horizontal swipe: scrub turn
+        if (!viewer.getReplay()) return;
+        if (dx < 0) {
+          viewer.setTurn(viewer.getTurn() + 1);
+        } else {
+          viewer.setTurn(viewer.getTurn() - 1);
+        }
+        updateUI(); updateEventLog(); updateMobileUI(); updateMobileTimeline();
+      }
+    }
+
+    if (activePointers.size < 2) {
+      pinchStartDist = 0;
+    }
+  });
+
+  canvas.addEventListener('pointercancel', (e: PointerEvent) => {
+    activePointers.delete(e.pointerId);
+    if (activePointers.size < 2) pinchStartDist = 0;
+  });
+
   // Commentary toggle
   commentaryToggle.addEventListener('click', () => {
     commentaryEnabled = !commentaryEnabled;

web/src/replay-viewer.ts

@@ -576,6 +576,18 @@ export class ReplayViewer {
     return this.viewMode;
   }
 
+  setCellSize(size: number): void {
+    this.cellSize = Math.max(4, Math.min(20, Math.round(size)));
+    if (this.replay) {
+      this.resizeCanvas();
+      this.render();
+    }
+  }
+
+  getCellSize(): number {
+    return this.cellSize;
+  }
+
   setShowDebug(show: boolean): void {
     this.showDebug = show;
     this.render();

web/src/styles/mobile.css

@@ -167,6 +167,33 @@
     font-weight: 500;
   }
 
+  /* Win probability sparkline — full width on mobile */
+  .win-prob-section {
+    margin-top: 8px;
+  }
+
+  .win-prob-header {
+    flex-direction: column;
+    align-items: flex-start;
+    gap: 6px;
+  }
+
+  .critical-moment-nav {
+    font-size: 0.75rem;
+  }
+
+  /* Commentary — scrollable on mobile if text is long */
+  .commentary-bar {
+    flex-wrap: wrap;
+    gap: 6px;
+  }
+
+  .commentary-content {
+    max-height: 60px;
+    overflow-y: auto;
+    -webkit-overflow-scrolling: touch;
+  }
+
   /* Replay viewer mobile */
   .replay-page .page-title {
     font-size: 1.25rem;
@@ -188,8 +215,13 @@
   }
 
   .canvas-wrapper {
-    padding: var(--space-xs);
+    padding: 0 !important;
     border-radius: var(--radius-md);
+    /* Square viewport so canvas fills the full phone width */
+    width: 100%;
+    aspect-ratio: 1;
+    max-height: none !important;
+    overflow: hidden;
   }
 
   /* Mobile replay controls - compact bar below canvas */