fix(engine): exports no longer fail on a video clip outside the composition's length

A clip that starts at or after the composition's end (or ends before 0) is
never on screen, so extraction skips it. Its timeline window stayed as
authored, so the frame-coverage gate still expected its full length and
aborted the render with "captured 0 of expected N frames". Such a clip now
leaves extraction with an empty window, the same way a partly visible clip
is already trimmed to its visible part, so it owes no frames.

Author: miguel-heygen

packages/engine/src/services/videoFrameExtractor.test.ts

@@ -2286,6 +2286,31 @@ describe.skipIf(!HAS_FFMPEG)("extractAllVideoFrames on a VFR source", () => {
     });
 
     expect(result).toMatchObject({ success: true, extracted: [], errors: [] });
+    // Frame coverage reads this window; a clip never on screen owes no frames.
+    expect(video).toMatchObject({ start: -2, end: -2 });
+  });
+
+  it("gives a clip starting after the timeline end an empty window, not an error", async () => {
+    const outputDir = join(FIXTURE_DIR, "out-after-timeline");
+    mkdirSync(outputDir, { recursive: true });
+    const video: VideoElement = {
+      id: "after-timeline",
+      src: VFR_FIXTURE,
+      start: 4,
+      end: 6,
+      mediaStart: 0,
+      loop: false,
+      hasAudio: false,
+    };
+
+    const result = await extractAllVideoFrames([video], FIXTURE_DIR, {
+      fps: 1,
+      outputDir,
+      timelineEnd: 3,
+    });
+
+    expect(result).toMatchObject({ success: true, extracted: [], errors: [] });
+    expect(video).toMatchObject({ start: 4, end: 4 });
   });
 
   it("preserves loop phase when negative preroll crosses the source boundary", async () => {

packages/engine/src/services/videoFrameExtractor.ts

@@ -1348,6 +1348,11 @@ function canHoldFinalFramePastEof(video: TimelineWindowVideo): boolean {
 // one frame, while FFmpeg seeks to the separately probed real frame timestamp.
 const FINAL_FRAME_LOGICAL_DURATION_SECONDS = 1e-6;
 
+/** A clip entirely outside the render timeline is never on screen, so it owes no frames. */
+function clearVideoWindow(video: VideoElement): void {
+  video.end = video.start;
+}
+
 /** Move a clip to its extraction window; a rate lane is shifted so it keeps integrating from the new origin. */
 export function rebaseVideoToWindow(video: VideoElement, window: TimelineExtractionWindow): void {
   if (window.preserveTimelinePhase) return;
@@ -1868,7 +1873,10 @@ export async function extractAllVideoFrames(
   const warnedSrcs = new Set<string>();
   for (const video of videos) {
     if (signal?.aborted) break;
-    if (options.timelineEnd !== undefined && video.start >= options.timelineEnd) continue;
+    if (options.timelineEnd !== undefined && video.start >= options.timelineEnd) {
+      clearVideoWindow(video);
+      continue;
+    }
     try {
       let videoPath = video.src;
       if (!isHttpUrl(videoPath)) {
@@ -2452,6 +2460,7 @@ export async function extractAllVideoFrames(
         );
         const videoDuration = window.durationSeconds;
         if (videoDuration <= 0) {
+          clearVideoWindow(video);
           return { skipped: true };
         }
         rebaseVideoToWindow(video, window);