diff --git a/electron/ipc/recording/diagnostics.test.ts b/electron/ipc/recording/diagnostics.test.ts
index 9f7ddeb08..a0092a602 100644
--- a/electron/ipc/recording/diagnostics.test.ts
+++ b/electron/ipc/recording/diagnostics.test.ts
@@ -134,6 +134,42 @@ describe("getCompanionAudioFallbackPaths", () => {
 		]);
 	});
 
+	it("returns both mac sidecars instead of the video when a system sidecar exists", async () => {
+		const videoPath = path.join(tempRoot, "recording.mp4");
+		const systemPath = path.join(tempRoot, "recording.system.m4a");
+		const micPath = path.join(tempRoot, "recording.mic.m4a");
+
+		await Promise.all([
+			fs.writeFile(videoPath, "video"),
+			fs.writeFile(systemPath, "system"),
+			fs.writeFile(micPath, "mic"),
+		]);
+
+		execFileMock.mockImplementation(
+			(
+				_file: string,
+				_args: string[],
+				_options: Record<string, unknown>,
+				callback: ExecFileCallback,
+			) => {
+				const error = new Error("ffmpeg probe found embedded audio") as Error & {
+					stderr?: string;
+				};
+				error.stderr = "Stream #0:1: Audio: aac";
+				callback(error, "", error.stderr);
+			},
+		);
+
+		const { getCompanionAudioFallbackPaths } = await import("./diagnostics");
+
+		// The inline mp4 track holds system audio only, so returning [videoPath]
+		// here silently dropped the microphone.
+		await expect(getCompanionAudioFallbackPaths(videoPath)).resolves.toEqual([
+			systemPath,
+			micPath,
+		]);
+	});
+
 	it("prefers the mac mic companion alone when embedded audio already exists and no system sidecar is present", async () => {
 		const videoPath = path.join(tempRoot, "recording.mp4");
 		const micPath = path.join(tempRoot, "recording.mic.m4a");
diff --git a/electron/ipc/recording/diagnostics.ts b/electron/ipc/recording/diagnostics.ts
index 985209f22..76a9a343d 100644
--- a/electron/ipc/recording/diagnostics.ts
+++ b/electron/ipc/recording/diagnostics.ts
@@ -496,6 +496,16 @@ export async function getCompanionAudioFallbackPaths(videoPath: string) {
 	return paths;
 }
 
+/**
+ * Resolve which audio files the editor should play alongside `videoPath`, and
+ * the start delay recorded for each.
+ *
+ * The renderer treats a `.system.`/`.mic.` pair as independent tracks and mutes
+ * the video's own track when both are present.  The macOS helper writes system
+ * audio to the inline track but keeps both sources as sidecars, so once a mac
+ * system sidecar exists the sidecars are authoritative and are returned in place
+ * of the video.  Other layouts keep the embedded track and add the mic sidecar.
+ */
 export async function getCompanionAudioFallbackInfo(videoPath: string) {
 	const companionCandidates = await getUsableCompanionAudioCandidates(videoPath);
 	if (companionCandidates.length === 0) {
@@ -524,7 +534,17 @@ export async function getCompanionAudioFallbackInfo(videoPath: string) {
 		if (!hasUsableMacSystemCompanion && usableMacMicOnlyCompanions.length > 0) {
 			paths = usableMacMicOnlyCompanions;
 		} else if (hasUsableMacSystemCompanion) {
-			paths = [videoPath];
+			// The inline mp4 audio track carries system audio only (the helper skips
+			// the microphone while system audio is captured), so returning the video
+			// alone drops the mic entirely.  Hand over both mac sidecars instead and
+			// let the renderer route them as independent system/mic tracks.
+			paths = Array.from(
+				new Set(
+					companionCandidates.flatMap((candidate) =>
+						candidate.platform === "mac" ? candidate.usablePaths : [],
+					),
+				),
+			);
 		} else {
 			const companionPaths = Array.from(
 				new Set(