fix(export): validate edited-track fast-path inputs

src/lib/exporter/editedTrackStrategy.test.ts

@@ -100,6 +100,23 @@ describe("editedTrackStrategy", () => {
 		).toBe("offline-render-fallback");
 	});
 
+	it("falls back when source duration or speed-region bounds are invalid", () => {
+		const invalidBounds: SpeedRegion[] = [
+			{ id: "speed-1", startMs: Number.NaN, endMs: 10_000, speed: 1.5 },
+		];
+
+		expect(
+			classifyEditedTrackStrategy({
+				primaryAudioSourcePath: "recording.mp4",
+				sourceDurationMs: Number.POSITIVE_INFINITY,
+				trimRegions: EMPTY_TRIMS,
+				speedRegions: invalidBounds,
+				audioRegions: [],
+				sourceAudioFallbackPaths: [],
+			}),
+		).toBe("offline-render-fallback");
+	});
+
 	it("builds source segments that preserve trims and speed boundaries", () => {
 		const trimRegions: TrimRegion[] = [{ id: "trim-1", startMs: 10_000, endMs: 12_000 }];
 		const speedRegions: SpeedRegion[] = [
@@ -118,4 +135,12 @@ describe("editedTrackStrategy", () => {
 			{ startMs: 18_000, endMs: 20_000, speed: 1 },
 		]);
 	});
+
+	it("returns no source segments when speed-region bounds are invalid", () => {
+		expect(
+			buildEditedTrackSourceSegments(SOURCE_DURATION_MS, EMPTY_TRIMS, [
+				{ id: "speed-1", startMs: 15_000, endMs: 10_000, speed: 1.5 },
+			]),
+		).toEqual([]);
+	});
 });

src/lib/exporter/editedTrackStrategy.ts

@@ -26,8 +26,29 @@ function isSafeFiltergraphSpeed(speed: number): boolean {
 	);
 }
 
-function hasSafeFiltergraphSpeedRegions(speedRegions: SpeedRegion[]): boolean {
-	return speedRegions.every((region) => isSafeFiltergraphSpeed(region.speed));
+function hasFiniteTimelineRange(startMs: number, endMs: number, sourceDurationMs: number): boolean {
+	return (
+		Number.isFinite(startMs) &&
+		Number.isFinite(endMs) &&
+		startMs >= 0 &&
+		endMs > startMs &&
+		endMs <= sourceDurationMs
+	);
+}
+
+function hasSafeFiltergraphSpeedRegions(
+	speedRegions: SpeedRegion[],
+	sourceDurationMs: number,
+): boolean {
+	if (!Number.isFinite(sourceDurationMs) || sourceDurationMs <= 0) {
+		return false;
+	}
+
+	return speedRegions.every(
+		(region) =>
+			hasFiniteTimelineRange(region.startMs, region.endMs, sourceDurationMs) &&
+			isSafeFiltergraphSpeed(region.speed),
+	);
 }
 
 function buildKeptRanges(
@@ -64,6 +85,20 @@ export function buildEditedTrackSourceSegments(
 	trimRegions: TrimRegion[],
 	speedRegions: SpeedRegion[],
 ): EditedTrackSourceSegment[] {
+	if (!Number.isFinite(sourceDurationMs) || sourceDurationMs <= 0) {
+		return [];
+	}
+
+	if (
+		speedRegions.some(
+			(region) =>
+				!hasFiniteTimelineRange(region.startMs, region.endMs, sourceDurationMs) ||
+				!isSafeFiltergraphSpeed(region.speed),
+		)
+	) {
+		return [];
+	}
+
 	const segments: EditedTrackSourceSegment[] = [];
 	const keptRanges = buildKeptRanges(sourceDurationMs, trimRegions);
 
@@ -119,7 +154,7 @@ export function classifyEditedTrackStrategy(input: EditedTrackStrategyInput): Ed
 		return "offline-render-fallback";
 	}
 
-	if (!hasSafeFiltergraphSpeedRegions(input.speedRegions)) {
+	if (!hasSafeFiltergraphSpeedRegions(input.speedRegions, input.sourceDurationMs)) {
 		return "offline-render-fallback";
 	}