feat(playground): expand gamepad support with face buttons and Steam Deck fixes

- Map A=Train, B=Clear Examples, X=Randomize, LB=Thumbs Down, RB=Thumbs Up
- Add periodic gamepad polling fallback for environments where
  gamepadconnected event doesn't fire reliably (Steam Deck, some Linux browsers)
- Show "Press any gamepad button to connect" hint on page load

playground/js/a-app.js

@@ -1365,14 +1365,23 @@ function wireGamepad() {
       onJoystickMove();
     },
     onButton: (btn) => {
-      if (btn === 'rb') onThumbsUp();
       if (btn === 'lb') onThumbsDown();
+      if (btn === 'rb') onThumbsUp();
+      if (btn === 'a') onTrain();
+      if (btn === 'x') onRandomize();
+      if (btn === 'b') onClearExamples();
     },
     onConnectionChange: (connected) => {
       const el = document.getElementById('gamepad-status');
-      if (el) el.textContent = connected ? 'Gamepad connected' : '';
+      if (el) el.textContent = connected ? 'Gamepad connected' : 'Press any button to activate gamepad';
     },
   });
+
+  // Show hint immediately if no gamepad detected yet
+  if (!gamepad.connected) {
+    const el = document.getElementById('gamepad-status');
+    if (el) el.textContent = 'Press any gamepad button to connect';
+  }
 }
 
 // ---- Keyboard ----

playground/js/b-app.js

@@ -1241,15 +1241,23 @@ function init() {
       mappingView.drawOverlay();
     },
     onButton: (btn) => {
-      if (btn === 'rb') onThumbsUp();
       if (btn === 'lb') onThumbsDown();
+      if (btn === 'rb') onThumbsUp();
+      if (btn === 'a') onTrain();
+      if (btn === 'x') onRandomize();
+      if (btn === 'b') onClearExamples();
     },
     onConnectionChange: (connected) => {
       const el = document.getElementById('gamepad-status');
-      if (el) el.textContent = connected ? 'Gamepad connected' : '';
+      if (el) el.textContent = connected ? 'Gamepad connected' : 'Press any button to activate gamepad';
     },
   });
 
+  if (!gamepad.connected) {
+    const el = document.getElementById('gamepad-status');
+    if (el) el.textContent = 'Press any gamepad button to connect';
+  }
+
   // Resize
   window.addEventListener('resize', () => {
     visualizer.resize();

playground/js/c-app.js

@@ -287,15 +287,20 @@ function init() {
       drawJoystick();
     },
     onButton: (btn) => {
-      if (btn === 'rb') onThumbsUp();
       if (btn === 'lb') onThumbsDown();
+      if (btn === 'rb') onThumbsUp();
     },
     onConnectionChange: (connected) => {
       const el = document.getElementById('gamepad-status');
-      if (el) el.textContent = connected ? 'Gamepad connected' : '';
+      if (el) el.textContent = connected ? 'Gamepad connected' : 'Press any button to activate gamepad';
     },
   });
 
+  if (!gamepad.connected) {
+    const el = document.getElementById('gamepad-status');
+    if (el) el.textContent = 'Press any gamepad button to connect';
+  }
+
   // Follow mode wiring
   wireFollowMode();
 

playground/js/ui/gamepad.js

@@ -37,6 +37,17 @@ export class GamepadInput {
 
     // Check if a gamepad is already connected
     this._findGamepad();
+
+    // Periodic fallback: some environments (Steam Deck, some Linux browsers)
+    // don't fire gamepadconnected reliably. Poll every 500ms until found.
+    this._probeInterval = setInterval(() => {
+      if (!this.connected) {
+        this._findGamepad();
+      } else {
+        clearInterval(this._probeInterval);
+        this._probeInterval = null;
+      }
+    }, 500);
   }
 
   _onConnected(e) {
@@ -126,18 +137,17 @@ export class GamepadInput {
       this.onMove(mappedX, mappedY);
     }
 
-    // Buttons: LB=4, RB=5
+    // Buttons: A=0, B=1, X=2, Y=3, LB=4, RB=5
     if (this.onButton) {
-      const lbPressed = !!gp.buttons[4]?.pressed;
-      const rbPressed = !!gp.buttons[5]?.pressed;
-      const lbPrev = !!this._buttonsPrev[4];
-      const rbPrev = !!this._buttonsPrev[5];
-
-      if (lbPressed && !lbPrev) this.onButton('lb');
-      if (rbPressed && !rbPrev) this.onButton('rb');
-
-      this._buttonsPrev[4] = lbPressed;
-      this._buttonsPrev[5] = rbPressed;
+      const watched = [0, 1, 2, 3, 4, 5];
+      const names = ['a', 'b', 'x', 'y', 'lb', 'rb'];
+      for (let i = 0; i < watched.length; i++) {
+        const idx = watched[i];
+        const pressed = !!gp.buttons[idx]?.pressed;
+        const prev = !!this._buttonsPrev[idx];
+        if (pressed && !prev) this.onButton(names[i]);
+        this._buttonsPrev[idx] = pressed;
+      }
     }
 
     return moved;
@@ -153,5 +163,6 @@ export class GamepadInput {
   destroy() {
     window.removeEventListener('gamepadconnected', this._onConnected);
     window.removeEventListener('gamepaddisconnected', this._onDisconnected);
+    if (this._probeInterval) clearInterval(this._probeInterval);
   }
 }