fix(avatar): use Pixi resizeTo for native canvas sizing; remove all manual CSS/ResizeObserver

Previous approach set CSS width:100% on a low-res canvas, causing the browser
to stretch/pixelate the model. Now using Pixi's built-in resizeTo so the
canvas internal resolution always matches the container. Model scaled to 90%
of container with centered anchor.

frontend/src/components/KiraAvatar.tsx

@@ -23,7 +23,7 @@ const OUTFIT_TEXTURES: Record<string, string> = {
 };
 
 export default function KiraAvatar(props: Props) {
-  const canvasRef = useRef<HTMLDivElement>(null);
+  const wrapRef = useRef<HTMLDivElement>(null);
   const modelRef = useRef<any>(null);
   const textureRef = useRef<any>(null);
   const lipSyncRef = useRef<number>(0);
@@ -35,21 +35,11 @@ export default function KiraAvatar(props: Props) {
   // Initialize Live2D
   useEffect(() => {
     let mounted = true;
-    const container = canvasRef.current;
+    const container = wrapRef.current;
     if (!container) return;
 
     let app: any = null;
     let model: any = null;
-    let canvasEl: HTMLCanvasElement | null = null;
-
-    const fitModel = (crW: number, crH: number) => {
-      if (!model || !app) return;
-      const maxW = crW * 0.45;
-      const maxH = crH * 0.45;
-      const s = Math.min(maxW / model.width, maxH / model.height);
-      model.scale.set(s);
-      model.position.set(app.screen.width / 2, app.screen.height / 2);
-    };
 
     const init = async () => {
       try {
@@ -61,14 +51,8 @@ export default function KiraAvatar(props: Props) {
         const { Live2DModel } = await import('pixi-live2d-display/cubism4');
         (Live2DModel as any).registerTicker(Ticker as any);
 
-        // Measure real container size (flex layout may not be ready on first paint)
-        const rect = container.getBoundingClientRect();
-        const w = Math.max(Math.round(rect.width), 260);
-        const h = Math.max(Math.round(rect.height), 260);
-
         app = new Application({
-          width: w,
-          height: h,
+          resizeTo: container,
           antialias: true,
           resolution: Math.min(window.devicePixelRatio || 1, 2),
           backgroundAlpha: 0,
@@ -76,30 +60,31 @@ export default function KiraAvatar(props: Props) {
         });
         if (!mounted) { app.destroy(true); return; }
 
-        // Force canvas to fill container via CSS so it never overflows
-        const canvas = app.view as HTMLCanvasElement;
-        canvas.style.width = '100%';
-        canvas.style.height = '100%';
-        canvas.style.display = 'block';
-        container.appendChild(canvas);
-        canvasEl = canvas;
+        container.appendChild(app.view as HTMLCanvasElement);
 
         model = await Live2DModel.from('/live2d/models/kira/kira.model3.json', {
           autoInteract: false,
         });
         modelRef.current = model;
 
-        // Fit model with generous margin to avoid clipping
-        const maxW = w * 0.45;
-        const maxH = h * 0.45;
-        const scale = Math.min(maxW / model.width, maxH / model.height);
-        model.scale.set(scale);
-        model.anchor.set(0.5, 0.5);
-        model.position.set(app.screen.width / 2, app.screen.height / 2);
+        const fit = () => {
+          const sw = app.screen.width;
+          const sh = app.screen.height;
+          // Scale to fit within the container, leaving margin so nothing clips
+          const margin = 0.9; // 90% of container
+          const s = Math.min((sw * margin) / model.width, (sh * margin) / 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;
 
+        // Re-fit on resize
+        app.renderer.on('resize', fit);
+
         try {
           textureRef.current = {
             index: 2,
@@ -125,28 +110,10 @@ export default function KiraAvatar(props: Props) {
       }
     };
 
-    // Use ResizeObserver so we init with the real laid-out size
-    const ro = new ResizeObserver((entries) => {
-      const cr = entries[0].contentRect;
-      if (app) {
-        // Already init'd — handle resize
-        app.renderer.resize(Math.round(cr.width), Math.round(cr.height));
-        // Re-apply CSS 100% because Pixi resize() overwrites inline styles
-        if (canvasEl) {
-          canvasEl.style.width = '100%';
-          canvasEl.style.height = '100%';
-        }
-        fitModel(cr.width, cr.height);
-        return;
-      }
-      // First measurement — run init
-      init();
-    });
-    ro.observe(container);
+    init();
 
     return () => {
       mounted = false;
-      ro.disconnect();
       cancelAnimationFrame(lipSyncRef.current);
       clearInterval(idleExprRef.current ?? undefined);
       if (app) { app.destroy(true, { children: true }); }
@@ -160,9 +127,7 @@ export default function KiraAvatar(props: Props) {
   useEffect(() => {
     const model = modelRef.current;
     if (!model || !live2dReady) return;
-
     cancelAnimationFrame(lipSyncRef.current);
-
     if (props.isSpeaking) {
       let phase = 0;
       const animate = () => {
@@ -170,8 +135,7 @@ export default function KiraAvatar(props: Props) {
         const openness = 0.25 + Math.sin(phase) * 0.35;
         try {
           model.internalModel.coreModel.setParameterValueByIndex(
-            findParam(model, 'PARAM_MOUTH_OPEN_Y'),
-            openness,
+            findParam(model, 'PARAM_MOUTH_OPEN_Y'), openness,
           );
         } catch { /* */ }
         lipSyncRef.current = requestAnimationFrame(animate);
@@ -180,12 +144,10 @@ export default function KiraAvatar(props: Props) {
     } else {
       try {
         model.internalModel.coreModel.setParameterValueByIndex(
-          findParam(model, 'PARAM_MOUTH_OPEN_Y'),
-          0,
+          findParam(model, 'PARAM_MOUTH_OPEN_Y'), 0,
         );
       } catch { /* */ }
     }
-
     return () => cancelAnimationFrame(lipSyncRef.current);
   }, [props.isSpeaking, live2dReady]);
 
@@ -193,10 +155,8 @@ export default function KiraAvatar(props: Props) {
   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');
@@ -218,7 +178,6 @@ export default function KiraAvatar(props: Props) {
     if (!model || !live2dReady) return;
   }, [props.accessory, live2dReady]);
 
-  // Inline styles
   const pulseStyle = `
     @keyframes listening-pulse {
       0%, 100% { box-shadow: 0 0 0 0 rgba(248, 113, 113, 0.4); }
@@ -232,11 +191,8 @@ export default function KiraAvatar(props: Props) {
   return (
     <div className="flex flex-col items-center w-full h-full overflow-hidden">
       <div className="relative w-full flex-1" style={{ minHeight: 250 }}>
-        <div
-          ref={canvasRef}
-          className="w-full h-full"
-          style={{ display: live2dReady ? 'block' : 'none' }}
-        />
+        {/* Pixi canvas mounts here */}
+        <div ref={wrapRef} className="w-full h-full" />
 
         {/* SVG fallback when Live2D fails */}
         {(!live2dReady || loadError) && (
@@ -319,8 +275,6 @@ export default function KiraAvatar(props: Props) {
   );
 }
 
-// Helpers
-
 function loadScript(src: string): Promise<void> {
   return new Promise((resolve, reject) => {
     if (document.querySelector('script[src="' + src + '"]')) { resolve(); return; }