Fix: stop mic fallback recorder when cancelling native recording

Cancelling a native-capture recording (clicking the "X"/cancel button)
never stopped the mic fallback recorder's getUserMedia stream. The
stale mic track stayed open, so starting the next recording opened a
second concurrent mic stream and produced silent/dead audio until the
user manually reselected the microphone.

cancelRecording's native-capture branch now stops the mic fallback
recorder alongside discarding the native capture, mirroring the
cleanup stopRecording already performs.

Fixes #699

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/hooks/useScreenRecorder.test.ts

@@ -397,6 +397,7 @@ function cancelRecording(
 	chunks: { current: Blob[] },
 	webcamRecorder?: ReturnType<typeof createMockMediaRecorder> | null,
 	webcamChunks?: { current: Blob[] },
+	stopMicFallbackRecorder?: () => Promise<Blob | null>,
 ) {
 	if (webcamChunks) webcamChunks.current = [];
 	if (webcamRecorder && webcamRecorder.state !== "inactive") {
@@ -404,6 +405,7 @@ function cancelRecording(
 	}
 
 	if (isNativeRecording) {
+		void stopMicFallbackRecorder?.();
 		return { cancelled: true, wasNative: true };
 	}
 
@@ -740,6 +742,23 @@ describe("useScreenRecorder state machine", () => {
 			expect(recorder.stop).not.toHaveBeenCalled();
 		});
 
+		it("stops the mic fallback recorder when cancelling native recording", () => {
+			const chunks = { current: [] as Blob[] };
+			const stopMicFallbackRecorder = vi.fn(() => Promise.resolve(null));
+
+			const result = cancelRecording(
+				recorder,
+				true,
+				chunks,
+				null,
+				undefined,
+				stopMicFallbackRecorder,
+			);
+
+			expect(result.wasNative).toBe(true);
+			expect(stopMicFallbackRecorder).toHaveBeenCalled();
+		});
+
 		it("handles cancel when recorder is already inactive", () => {
 			const inactiveRecorder = createMockMediaRecorder("inactive");
 			const chunks = { current: [new Blob(["data"])] };

src/hooks/useScreenRecorder.ts

@@ -2394,7 +2394,7 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			setRecording(false);
 			window.electronAPI?.setRecordingState(false);
 			void (async () => {
-				await discardActiveNativeCapture();
+				await Promise.allSettled([discardActiveNativeCapture(), stopMicFallbackRecorder()]);
 			})();
 			return;
 		}
@@ -2408,7 +2408,13 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			setRecording(false);
 			window.electronAPI?.setRecordingState(false);
 		}
-	}, [cleanupCapturedMedia, discardActiveNativeCapture, markRecordingResumed, recording]);
+	}, [
+		cleanupCapturedMedia,
+		discardActiveNativeCapture,
+		markRecordingResumed,
+		recording,
+		stopMicFallbackRecorder,
+	]);
 
 	const toggleRecording = async () => {
 		if (starting || countdownActive || finalizing) {