fix: track animation ended state and wire preview controls correctly

- Replace boolean paused with AnimState ('playing'|'paused'|'ended')
- Use onAnimationEnd to detect when finite animations finish
- Play re-enables after end and restarts the animation (replay)
- Pause only active while playing; Restart always available
- Config changes auto-restart preview so edits are instantly visible

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

components/animate/AnimationPreview.tsx

@@ -14,6 +14,8 @@ interface Props {
   onElementChange: (e: PreviewElement) => void;
 }
 
+type AnimState = 'playing' | 'paused' | 'ended';
+
 const SPEEDS: { label: string; value: string }[] = [
   { label: '0.25×', value: '0.25' },
   { label: '0.5×', value: '0.5' },
@@ -23,9 +25,8 @@ const SPEEDS: { label: string; value: string }[] = [
 
 export function AnimationPreview({ config, element, onElementChange }: Props) {
   const styleRef = useRef<HTMLStyleElement | null>(null);
-  const elementRef = useRef<HTMLDivElement>(null);
   const [restartKey, setRestartKey] = useState(0);
-  const [paused, setPaused] = useState(false);
+  const [animState, setAnimState] = useState<AnimState>('playing');
   const [speed, setSpeed] = useState('1');
 
   // Inject @keyframes CSS into document head
@@ -36,21 +37,32 @@ export function AnimationPreview({ config, element, onElementChange }: Props) {
       document.head.appendChild(styleRef.current);
     }
     styleRef.current.textContent = buildCSS(config);
+    // Restart preview whenever config changes so changes are immediately visible
+    setAnimState('playing');
+    setRestartKey((k) => k + 1);
   }, [config]);
 
   // Cleanup on unmount
   useEffect(() => {
-    return () => {
-      styleRef.current?.remove();
-    };
+    return () => { styleRef.current?.remove(); };
   }, []);
 
   const restart = () => {
-    setPaused(false);
+    setAnimState('playing');
     setRestartKey((k) => k + 1);
   };
 
+  const handlePlay = () => {
+    if (animState === 'ended') {
+      // Animation finished — restart it
+      restart();
+    } else {
+      setAnimState('playing');
+    }
+  };
+
   const scaledDuration = Math.round(config.duration / Number(speed));
+  const isInfinite = config.iterationCount === 'infinite';
 
   return (
     <Card className="h-full flex flex-col">
@@ -79,12 +91,12 @@ export function AnimationPreview({ config, element, onElementChange }: Props) {
           {/* Animated element */}
           <div
             key={restartKey}
-            ref={elementRef}
             className="animated relative z-10"
             style={{
               animationDuration: `${scaledDuration}ms`,
-              animationPlayState: paused ? 'paused' : 'running',
+              animationPlayState: animState === 'paused' ? 'paused' : 'running',
             }}
+            onAnimationEnd={() => !isInfinite && setAnimState('ended')}
           >
             {element === 'box' && (
               <div className="w-20 h-20 rounded-xl bg-gradient-to-br from-violet-500 to-purple-600 shadow-lg shadow-purple-500/30" />
@@ -118,17 +130,17 @@ export function AnimationPreview({ config, element, onElementChange }: Props) {
             <Button
               size="icon-xs"
               variant="outline"
-              onClick={() => { setPaused(false); }}
-              disabled={!paused}
-              title="Play"
+              onClick={handlePlay}
+              disabled={animState === 'playing'}
+              title={animState === 'ended' ? 'Replay' : 'Play'}
             >
               <Play className="h-3 w-3" />
             </Button>
             <Button
               size="icon-xs"
               variant="outline"
-              onClick={() => setPaused(true)}
-              disabled={paused}
+              onClick={() => setAnimState('paused')}
+              disabled={animState !== 'playing'}
               title="Pause"
             >
               <Pause className="h-3 w-3" />