refactor(live2d): single shared stage for both Kira and Mochi

Live2DStage creates ONE full-viewport transparent canvas (z-0, pointer-events:none).
Both Kira and Mochi cat models render on the same Pixi stage and WebGL context.
KiraAvatar is now UI-only (no canvas), receives model ref from stage.
PetZone is label-only. Eliminates all WebGL context conflict errors.

frontend/src/components/KiraAvatar.tsx

@@ -7,6 +7,10 @@ interface Props {
   outfit: string;
   accessory: string | null;
   onTalkToggle: () => void;
+  /** The Live2D Kira model instance (from Live2DStage) */
+  kiraModel: any;
+  live2dReady: boolean;
+  onExpressionChange?: (expr: string) => void;
 }
 
 type ExpressionName = 'Normal' | 'Smile' | 'Sad' | 'Angry' | 'Surprised' | 'Blushing';
@@ -14,117 +18,27 @@ type ExpressionName = 'Normal' | 'Smile' | 'Sad' | 'Angry' | 'Surprised' | 'Blus
 const EXPRESSIONS: ExpressionName[] = ['Normal', 'Smile', 'Sad', 'Angry', 'Surprised', 'Blushing'];
 const IDLE_EXPRESSIONS: ExpressionName[] = ['Normal', 'Smile', 'Blushing'];
 
-const OUTFIT_TEXTURES: Record<string, string> = {
-  'cozy-hoodie': '/live2d/models/kira/outfits/cozy-hoodie.png',
-  'girly-dress': '/live2d/models/kira/outfits/girly-dress.png',
-  'pajama-set': '/live2d/models/kira/outfits/pajama-set.png',
-  'study-sweater': '/live2d/models/kira/outfits/study-sweater.png',
-  'going-out': '/live2d/models/kira/outfits/going-out.png',
-};
-
 export default function KiraAvatar(props: Props) {
-  const canvasRef = useRef<HTMLCanvasElement>(null);
-  const modelRef = useRef<any>(null);
-  const textureRef = useRef<any>(null);
   const lipSyncRef = useRef<number>(0);
   const idleExprRef = useRef<ReturnType<typeof setInterval> | null>(null);
-  const [live2dReady, setLive2dReady] = useState(false);
-  const [loadError, setLoadError] = useState(false);
   const [currentExpression, setCurrentExpression] = useState<ExpressionName>('Normal');
 
+  // Idle expression cycling
   useEffect(() => {
-    let mounted = true;
-    const canvas = canvasRef.current;
-    if (!canvas) return;
-
-    let app: any = null;
-    let model: any = null;
-
-    const init = async () => {
-      try {
-        const resp = await fetch('/live2d/models/kira/kira.model3.json', { method: 'HEAD' });
-        if (!resp.ok) { if (mounted) setLoadError(true); return; }
-
-        await loadScript('/live2d/cubism/live2dcubismcore.min.js');
-        const { Application, Ticker } = await import('pixi.js');
-        const { Live2DModel } = await import('pixi-live2d-display/cubism4');
-        (Live2DModel as any).registerTicker(Ticker as any);
-
-        const w = canvas.clientWidth || 260;
-        const h = canvas.clientHeight || 320;
-
-        app = new Application({
-          view: canvas,
-          width: w,
-          height: h,
-          antialias: true,
-          resolution: Math.min(window.devicePixelRatio || 1, 2),
-          backgroundAlpha: 0,
-          autoDensity: true,
-        });
-        if (!mounted) { app.destroy(true); return; }
-
-        model = await Live2DModel.from('/live2d/models/kira/kira.model3.json', {
-          autoInteract: false,
-        });
-        modelRef.current = model;
-
-        const fit = () => {
-          const sw = app.screen.width;
-          const sh = app.screen.height;
-          const s = Math.min((sw * 0.82) / model.width, (sh * 0.82) / model.height);
-          model.scale.set(s);
-          model.anchor.set(0.5, 0.5);
-          model.position.set(sw / 2, sh / 2);
-        };
-        fit();
-
-        app.stage.addChild(model as any);
-        (model as any).isInteractive = () => false;
-        if (!mounted) return;
-
-        try {
-          textureRef.current = {
-            index: 2,
-            original: (model.internalModel.coreModel as any).getTexture(2),
-          };
-        } catch { /* ignore */ }
-
-        if (mounted) setLive2dReady(true);
-
-        try { model.motion('Idle'); } catch { /* no idle */ }
-        try { model.expression('Normal'); } catch { /* no expressions */ }
-
-        idleExprRef.current = setInterval(() => {
-          if (props.isSpeaking) return;
-          const expr = IDLE_EXPRESSIONS[Math.floor(Math.random() * IDLE_EXPRESSIONS.length)];
-          try { model.expression(expr); } catch { /* */ }
-          setCurrentExpression(expr);
-        }, 8000 + Math.random() * 7000);
-
-      } catch (e) {
-        console.warn('[Live2D]', e);
-        if (mounted) setLoadError(true);
-      }
-    };
-
-    init();
-
-    return () => {
-      mounted = false;
-      cancelAnimationFrame(lipSyncRef.current);
-      clearInterval(idleExprRef.current ?? undefined);
-      if (app) { app.destroy(true, { children: true }); }
-      modelRef.current = null;
-      textureRef.current = null;
-    };
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, []);
+    if (!props.kiraModel || !props.live2dReady) return;
+    idleExprRef.current = setInterval(() => {
+      if (props.isSpeaking) return;
+      const expr = IDLE_EXPRESSIONS[Math.floor(Math.random() * IDLE_EXPRESSIONS.length)];
+      try { props.kiraModel.expression(expr); } catch {}
+      setCurrentExpression(expr);
+    }, 8000 + Math.random() * 7000);
+    return () => clearInterval(idleExprRef.current ?? undefined);
+  }, [props.kiraModel, props.live2dReady, props.isSpeaking]);
 
   // Lip sync from TTS
   useEffect(() => {
-    const model = modelRef.current;
-    if (!model || !live2dReady) return;
+    const model = props.kiraModel;
+    if (!model || !props.live2dReady) return;
     cancelAnimationFrame(lipSyncRef.current);
     if (props.isSpeaking) {
       let phase = 0;
@@ -135,7 +49,7 @@ export default function KiraAvatar(props: Props) {
           model.internalModel.coreModel.setParameterValueByIndex(
             findParam(model, 'PARAM_MOUTH_OPEN_Y'), openness,
           );
-        } catch { /* */ }
+        } catch {}
         lipSyncRef.current = requestAnimationFrame(animate);
       };
       animate();
@@ -144,37 +58,10 @@ export default function KiraAvatar(props: Props) {
         model.internalModel.coreModel.setParameterValueByIndex(
           findParam(model, 'PARAM_MOUTH_OPEN_Y'), 0,
         );
-      } catch { /* */ }
+      } catch {}
     }
     return () => cancelAnimationFrame(lipSyncRef.current);
-  }, [props.isSpeaking, live2dReady]);
-
-  // Outfit texture swapping
-  useEffect(() => {
-    const model = modelRef.current;
-    if (!model || !live2dReady) return;
-    const outfitUrl = OUTFIT_TEXTURES[props.outfit];
-    if (!outfitUrl) return;
-    (async () => {
-      try {
-        const { Assets } = await import('pixi.js');
-        const tex = await Assets.load(outfitUrl);
-        if ((model as any).textures) {
-          (model as any).textures[2] = tex;
-        } else {
-          console.warn('[Outfit] cannot swap - no textures array');
-        }
-      } catch (e) {
-        console.warn('[Outfit] texture swap failed:', e);
-      }
-    })();
-  }, [props.outfit, live2dReady]);
-
-  // Accessory toggle
-  useEffect(() => {
-    const model = modelRef.current;
-    if (!model || !live2dReady) return;
-  }, [props.accessory, live2dReady]);
+  }, [props.isSpeaking, props.live2dReady, props.kiraModel]);
 
   const pulseStyle = `
     @keyframes listening-pulse {
@@ -187,17 +74,10 @@ export default function KiraAvatar(props: Props) {
   `;
 
   return (
-    <div className="flex flex-col items-center w-full h-full overflow-hidden">
+    <div className="flex flex-col items-center w-full h-full">
       <div className="relative w-full flex-1" style={{ minHeight: 250 }}>
-        {/* Live2D canvas */}
-        <canvas
-          ref={canvasRef}
-          className="w-full h-full block"
-          style={{ opacity: live2dReady ? 1 : 0 }}
-        />
-
-        {/* SVG fallback */}
-        {(!live2dReady || loadError) && (
+        {/* SVG fallback (shows before Live2D is ready) */}
+        {!props.live2dReady && (
           <div className="absolute inset-0 flex items-center justify-center">
             <AnimatedAvatar
               isSpeaking={props.isSpeaking}
@@ -209,8 +89,8 @@ export default function KiraAvatar(props: Props) {
           </div>
         )}
 
-        {/* Loading */}
-        {!live2dReady && !loadError && (
+        {/* Loading spinner */}
+        {!props.live2dReady && (
           <div className="absolute inset-0 flex flex-col items-center justify-center gap-2">
             <div className="w-8 h-8 border-3 border-kira-pink border-t-transparent rounded-full animate-spin" />
             <p className="text-[11px] text-kira-plum/40">loading Kira...</p>
@@ -218,7 +98,7 @@ export default function KiraAvatar(props: Props) {
         )}
 
         {/* Expression buttons */}
-        {live2dReady && (
+        {props.live2dReady && (
           <>
             <div className="absolute top-1 left-0 right-0 flex gap-1 justify-center flex-wrap pointer-events-none">
               <div className="pointer-events-auto flex gap-1 flex-wrap justify-center">
@@ -226,7 +106,7 @@ export default function KiraAvatar(props: Props) {
                   <button
                     key={expr}
                     onClick={() => {
-                      try { modelRef.current?.expression(expr); setCurrentExpression(expr); } catch {}
+                      try { props.kiraModel?.expression(expr); setCurrentExpression(expr); props.onExpressionChange?.(expr); } catch {}
                     }}
                     className={`text-[9px] px-2 py-0.5 rounded-full font-medium transition-all ${
                       currentExpression === expr
@@ -277,17 +157,6 @@ export default function KiraAvatar(props: Props) {
   );
 }
 
-function loadScript(src: string): Promise<void> {
-  return new Promise((resolve, reject) => {
-    if (document.querySelector('script[src="' + src + '"]')) { resolve(); return; }
-    const s = document.createElement('script');
-    s.src = src;
-    s.onload = () => resolve();
-    s.onerror = () => reject(new Error('Failed ' + src));
-    document.head.appendChild(s);
-  });
-}
-
 function findParam(model: any, name: string): number {
   try {
     return model.internalModel.coreModel.getParameterIds().indexOf(name);