fix(choreography): preserve spotlight fade easing

Author: YizukiAme

lib/choreography/descriptors/spotlight.ts

@@ -147,13 +147,28 @@ export const spotlightV1: AnimationDescriptor = {
       staticProps: { x: 0, y: 0, width: 100, height: 100, fill: 'rgba(0,0,0,{dimness})' },
       // The whole effect is wrapped in a motion.div that fades opacity 0→1 on
       // enter and →0 on exit. The source sets no explicit transition, so Motion
-      // applies its default tween (300ms) — pinned here explicitly so a
-      // non-Motion consumer (the exporter) reproduces the fade instead of
-      // popping the spotlight on/off. This layer carries the canonical wrapper
-      // fade; the border layer inherits its opacity so both fade out together.
+      // applies its default 300ms tween with [0.25, 0.1, 0.35, 1] easing. Both
+      // values are pinned here so consumers reproduce that implicit source
+      // transition instead of selecting a different engine default. This layer
+      // carries the canonical wrapper fade; the border layer inherits its
+      // opacity so both fade out together.
       tracks: [
-        { property: 'opacity', from: 0, to: 1, durationMs: 300, phase: 'enter' },
-        { property: 'opacity', from: 1, to: 0, durationMs: 300, phase: 'exit' },
+        {
+          property: 'opacity',
+          from: 0,
+          to: 1,
+          durationMs: 300,
+          easing: { type: 'cubicBezier', points: [0.25, 0.1, 0.35, 1] },
+          phase: 'enter',
+        },
+        {
+          property: 'opacity',
+          from: 1,
+          to: 0,
+          durationMs: 300,
+          easing: { type: 'cubicBezier', points: [0.25, 0.1, 0.35, 1] },
+          phase: 'exit',
+        },
       ],
     },
   ],

tests/components/slide-renderer/motion-descriptor-adapter.test.ts

@@ -33,9 +33,13 @@ describe('resolveMotionLayer', () => {
       animate: { opacity: 1 },
       exit: {
         opacity: 0,
-        transition: { opacity: { duration: 0.3 } },
+        transition: {
+          opacity: { duration: 0.3, ease: [0.25, 0.1, 0.35, 1] },
+        },
+      },
+      transition: {
+        opacity: { duration: 0.3, ease: [0.25, 0.1, 0.35, 1] },
       },
-      transition: { opacity: { duration: 0.3 } },
       staticProps: { x: 0, y: 0, width: 100, height: 100, fill: 'rgba(0,0,0,0)' },
     });
   });