fix(render): reject incomplete captured frames (#2293)

packages/producer/src/services/renderOrchestrator.test.ts

@@ -230,7 +230,7 @@ describe("executeDiskCaptureWithAdaptiveRetry — transient Target-closed single
 
   const writeAllFrames = (framesDir: string, totalFrames: number): void => {
     for (let i = 0; i < totalFrames; i++) {
-      writeFileSync(join(framesDir, formatCaptureFrameName(i, "jpg")), "x");
+      writeFileSync(join(framesDir, formatCaptureFrameName(i, "jpg")), "captured-frame");
     }
   };
 
@@ -1432,7 +1432,10 @@ describe("adaptive missing-frame retry helpers", () => {
   it("finds contiguous missing frame ranges from captured disk frames", () => {
     const framesDir = makeFramesDir();
     for (const frameIndex of [0, 1, 4]) {
-      writeFileSync(join(framesDir, `frame_${String(frameIndex).padStart(6, "0")}.jpg`), "x");
+      writeFileSync(
+        join(framesDir, `frame_${String(frameIndex).padStart(6, "0")}.jpg`),
+        "captured-frame",
+      );
     }
 
     expect(findMissingFrameRanges(6, framesDir, "jpg")).toEqual([
@@ -1441,6 +1444,18 @@ describe("adaptive missing-frame retry helpers", () => {
     ]);
   });
 
+  it("retries a worker placeholder instead of accepting a truncated sequence", () => {
+    const framesDir = makeFramesDir();
+    for (let frameIndex = 0; frameIndex < 4; frameIndex++) {
+      writeFileSync(
+        join(framesDir, `frame_${String(frameIndex).padStart(6, "0")}.jpg`),
+        frameIndex === 2 ? "x" : "captured-frame",
+      );
+    }
+
+    expect(findMissingFrameRanges(4, framesDir, "jpg")).toEqual([{ startFrame: 2, endFrame: 3 }]);
+  });
+
   it("builds retry batches that cap active workers per attempt", () => {
     const batches = buildMissingFrameRetryBatches(
       [

packages/producer/src/services/renderOrchestrator.ts

@@ -603,7 +603,12 @@ export function findMissingFrameRanges(
 
   for (let frameIndex = 0; frameIndex < totalFrames; frameIndex++) {
     const framePath = join(framesDir, formatCaptureFrameName(frameIndex, frameExt));
-    const missing = !existsSync(framePath);
+    // A capture worker can leave a zero/one-byte placeholder behind when it
+    // exits between creating the destination and writing the image. FFmpeg's
+    // image2 demuxer treats that as end-of-sequence but still exits 0, which
+    // used to let a truncated video be reported as successful. Real JPEG and
+    // PNG captures are necessarily larger than their 8-byte file signatures.
+    const missing = !existsSync(framePath) || statSync(framePath).size <= 8;
     if (missing && rangeStart === null) {
       rangeStart = frameIndex;
     } else if (!missing && rangeStart !== null) {