fix(export): tighten native audio safety guards

electron/ipc/export/native-video.test.ts

@@ -856,6 +856,16 @@ describe("buildNativeVideoAudioMuxArgs", () => {
 		expect(args.join(";")).not.toContain("-c:a;copy");
 	});
 
+	it("transcodes unknown source audio instead of copying unsafe codecs into MP4", () => {
+		const args = buildNativeVideoAudioMuxArgs("video.mp4", "source.wav", "out.mp4", {
+			audioMode: "copy-source",
+			outputDurationSec: 60,
+		});
+
+		expect(args).toEqual(expect.arrayContaining(["-c:a", "aac", "-b:a", "192k"]));
+		expect(args.join(";")).not.toContain("-c:a;copy");
+	});
+
 	it("keeps filtered audio on the AAC encode path", () => {
 		const args = buildNativeVideoAudioMuxArgs("video.mp4", "source.mp4", "out.mp4", {
 			audioMode: "trim-source",
@@ -906,6 +916,11 @@ describe("canCopyAudioCodecIntoMp4", () => {
 	it("blocks Opus so native exports transcode it to AAC for MP4", () => {
 		expect(canCopyAudioCodecIntoMp4("opus")).toBe(false);
 	});
+
+	it("blocks unknown codecs so sidecar WAV/PCM audio is encoded for MP4", () => {
+		expect(canCopyAudioCodecIntoMp4(undefined)).toBe(false);
+		expect(canCopyAudioCodecIntoMp4("")).toBe(false);
+	});
 });
 
 describe("validateNativeVideoStreamStats", () => {
@@ -1162,6 +1177,27 @@ describe("validateNvidiaCudaExportSummary", () => {
 		expect(issues).toEqual(["output audio duration is not positive"]);
 	});
 
+	it("rejects inline-audio CUDA output when the audio duration is missing", () => {
+		const issues = validateNvidiaCudaExportSummary(
+			{
+				success: true,
+				targetFrames: 300,
+				durationSec: 10,
+				nativeSummary: {
+					success: true,
+					frames: 300,
+					sourceTimestampMode: "pts",
+					selectionStage: "timestamp-mapped-callback",
+				},
+				outputVideo: { duration: "9.999900", nb_frames: "300" },
+				outputAudio: {},
+			},
+			{ durationSec: 10, targetFrames: 300, requiresTimelineSync: true },
+		);
+
+		expect(issues).toEqual(["missing output audio duration"]);
+	});
+
 	it("accepts audio CUDA output when the helper reports PTS-aligned selection", () => {
 		const issues = validateNvidiaCudaExportSummary(
 			{

electron/ipc/export/native-video.ts

@@ -436,7 +436,9 @@ export function validateNvidiaCudaExportSummary(
 	if (expected.requiresTimelineSync) {
 		if (!summary.outputAudio) {
 			issues.push("missing output audio stream");
-		} else if (outputAudioDurationSec !== null && outputAudioDurationSec <= 0) {
+		} else if (outputAudioDurationSec === null) {
+			issues.push("missing output audio duration");
+		} else if (outputAudioDurationSec <= 0) {
 			issues.push("output audio duration is not positive");
 		}
 	}
@@ -3903,7 +3905,7 @@ export async function resolveNativeVideoEncoder(
 export function canCopyAudioCodecIntoMp4(codec?: string | null) {
 	const normalized = (codec ?? "").trim().toLowerCase();
 	if (!normalized) {
-		return true;
+		return false;
 	}
 
 	return (