Preserve paused preview camera and defer composition until seek completion

src/components/video-editor/VideoPlayback.tsx

@@ -1044,9 +1044,9 @@ const VideoPlayback = forwardRef<VideoPlaybackRef, VideoPlaybackProps>(
 				});
 				cropBoundsRef.current = result.cropBounds;
 
-				// Reset camera container to identity
-				cameraContainer.scale.set(1);
-				cameraContainer.position.set(0, 0);
+				// Layout updates the media geometry, not the composed camera pose.
+				// In particular, a ResizeObserver notification while paused must not
+				// replace the exported spring position with an unzoomed frame.
 
 				const selectedId = selectedZoomIdRef.current;
 				const activeRegion = selectedId
@@ -1893,6 +1893,7 @@ const VideoPlayback = forwardRef<VideoPlaybackRef, VideoPlaybackProps>(
 				video,
 				getClips: () => clipRegionsRef.current,
 				onTime: (time, source) => {
+					timelineTimeRef.current = time;
 					if (source !== null) currentTimeRef.current = source * 1000;
 					onTimeUpdate(time);
 				},
@@ -1909,6 +1910,7 @@ const VideoPlayback = forwardRef<VideoPlaybackRef, VideoPlaybackProps>(
 			transport.seek(timelineTimeRef.current);
 			const handleSeeked = () => {
 				isSeekingRef.current = false;
+				shouldSnapPausedFrameRef.current = true;
 			};
 			const handleSeeking = () => {
 				isSeekingRef.current = true;
@@ -2016,6 +2018,7 @@ const VideoPlayback = forwardRef<VideoPlaybackRef, VideoPlaybackProps>(
 				if (
 					!shouldComposePreviewFrame({
 						motionMode,
+						isSeeking: isSeekingRef.current || Boolean(videoRef.current?.seeking),
 						contentTimeChanged,
 						shouldSnapPausedFrame: shouldSnapPausedFrameRef.current,
 					})

src/components/video-editor/videoPlayback/sceneMotion.test.ts

@@ -43,13 +43,13 @@ describe("resolveSceneZoomTarget", () => {
 });
 
 describe("resolvePreviewMotionMode", () => {
-	it("preserves the composed frame on a plain pause", () => {
+	it.each([false, true])("preserves a plain pause with classic mode %s", (zoomClassicMode) => {
 		expect(
 			resolvePreviewMotionMode({
 				isPlaying: false,
 				isSeeking: false,
 				shouldSnapPausedFrame: false,
-				zoomClassicMode: false,
+				zoomClassicMode,
 			}),
 		).toBe("preserve");
 	});
@@ -97,3 +97,16 @@ describe("shouldComposePreviewFrame", () => {
 		).toBe(true);
 	});
 });
+
+
+describe("preview seek completion", () => {
+	it("holds the composed frame until seeking finishes, even with a pending refresh", () => {
+		const pending = {
+			motionMode: "snap" as const,
+			contentTimeChanged: true,
+			shouldSnapPausedFrame: true,
+		};
+		expect(shouldComposePreviewFrame({ ...pending, isSeeking: true })).toBe(false);
+		expect(shouldComposePreviewFrame({ ...pending, isSeeking: false })).toBe(true);
+	});
+});

src/components/video-editor/videoPlayback/sceneMotion.ts

@@ -32,7 +32,7 @@ export function resolvePreviewMotionMode({
 	shouldSnapPausedFrame: boolean;
 	zoomClassicMode: boolean;
 }): PreviewMotionMode {
-	if (isSeeking || shouldSnapPausedFrame || zoomClassicMode) {
+	if (isSeeking || shouldSnapPausedFrame || (isPlaying && zoomClassicMode)) {
 		return "snap";
 	}
 
@@ -42,14 +42,17 @@ export function resolvePreviewMotionMode({
 /** Match export's one-composition-per-media-frame behavior. */
 export function shouldComposePreviewFrame({
 	motionMode,
+	isSeeking = false,
 	contentTimeChanged,
 	shouldSnapPausedFrame,
 }: {
 	motionMode: PreviewMotionMode;
+	isSeeking?: boolean;
 	contentTimeChanged: boolean;
 	shouldSnapPausedFrame: boolean;
 }): boolean {
-	if (motionMode === "preserve") {
+	// Do not consume the pending composition against the old decoded image.
+	if (isSeeking || motionMode === "preserve") {
 		return false;
 	}