fix(recording): allow stop while paused and guard native pause

  - Fix stopRecording to handle MediaRecorder 'paused' state by resuming
    before stopping, ensuring final data chunk is flushed
  - Guard pauseRecording as no-op for native recordings (macOS SCK /
    Windows WGC) that lack pause IPC support
  - Add 14 unit tests for pause/stop state machine

Author: gurpreetkaits

src/hooks/useScreenRecorder.test.ts

@@ -0,0 +1,233 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+/**
+ * Tests for the MediaRecorder pause/stop state machine logic
+ * extracted from useScreenRecorder.
+ *
+ * These verify that:
+ * - Stop works from both "recording" and "paused" states
+ * - Resume is called before stop when stopping from paused state
+ * - Pause is a no-op when already paused or not recording
+ * - Resume is a no-op when not paused
+ */
+
+function createMockMediaRecorder(initialState: RecordingState = "inactive") {
+	let _state: RecordingState = initialState;
+	return {
+		get state() {
+			return _state;
+		},
+		pause: vi.fn(() => {
+			if (_state === "recording") _state = "paused";
+		}),
+		resume: vi.fn(() => {
+			if (_state === "paused") _state = "recording";
+		}),
+		stop: vi.fn(() => {
+			_state = "inactive";
+		}),
+		start: vi.fn(() => {
+			_state = "recording";
+		}),
+	};
+}
+
+/**
+ * Extracted state machine logic matching useScreenRecorder's stopRecording,
+ * pauseRecording, and resumeRecording implementations.
+ */
+function stopRecording(
+	recorder: ReturnType<typeof createMockMediaRecorder>,
+	isNativeRecording: boolean,
+) {
+	if (isNativeRecording) {
+		return { stopped: true, wasNative: true };
+	}
+
+	const recorderState = recorder.state;
+	if (recorderState === "recording" || recorderState === "paused") {
+		if (recorderState === "paused") {
+			recorder.resume();
+		}
+		recorder.stop();
+		return { stopped: true, wasNative: false };
+	}
+	return { stopped: false, wasNative: false };
+}
+
+function pauseRecording(
+	recorder: ReturnType<typeof createMockMediaRecorder>,
+	recording: boolean,
+	paused: boolean,
+	isNativeRecording: boolean,
+): boolean {
+	if (!recording || paused) return false;
+	if (isNativeRecording) return false;
+	if (recorder.state === "recording") {
+		recorder.pause();
+		return true;
+	}
+	return false;
+}
+
+function resumeRecording(
+	recorder: ReturnType<typeof createMockMediaRecorder>,
+	recording: boolean,
+	paused: boolean,
+): boolean {
+	if (!recording || !paused) return false;
+	if (recorder.state === "paused") {
+		recorder.resume();
+		return true;
+	}
+	return false;
+}
+
+describe("useScreenRecorder state machine", () => {
+	let recorder: ReturnType<typeof createMockMediaRecorder>;
+
+	beforeEach(() => {
+		recorder = createMockMediaRecorder("recording");
+	});
+
+	describe("stopRecording", () => {
+		it("stops from recording state", () => {
+			const result = stopRecording(recorder, false);
+
+			expect(result.stopped).toBe(true);
+			expect(recorder.stop).toHaveBeenCalled();
+			expect(recorder.resume).not.toHaveBeenCalled();
+			expect(recorder.state).toBe("inactive");
+		});
+
+		it("resumes then stops from paused state", () => {
+			recorder.pause();
+			expect(recorder.state).toBe("paused");
+
+			const result = stopRecording(recorder, false);
+
+			expect(result.stopped).toBe(true);
+			expect(recorder.resume).toHaveBeenCalled();
+			expect(recorder.stop).toHaveBeenCalled();
+			expect(recorder.state).toBe("inactive");
+		});
+
+		it("resume is called before stop when paused", () => {
+			recorder.pause();
+			const callOrder: string[] = [];
+			recorder.resume.mockImplementation(() => {
+				callOrder.push("resume");
+			});
+			recorder.stop.mockImplementation(() => {
+				callOrder.push("stop");
+			});
+
+			stopRecording(recorder, false);
+
+			expect(callOrder).toEqual(["resume", "stop"]);
+		});
+
+		it("does nothing when already inactive", () => {
+			const inactiveRecorder = createMockMediaRecorder("inactive");
+
+			const result = stopRecording(inactiveRecorder, false);
+
+			expect(result.stopped).toBe(false);
+			expect(inactiveRecorder.stop).not.toHaveBeenCalled();
+		});
+
+		it("delegates to native path for native recordings", () => {
+			const result = stopRecording(recorder, true);
+
+			expect(result.stopped).toBe(true);
+			expect(result.wasNative).toBe(true);
+			expect(recorder.stop).not.toHaveBeenCalled();
+		});
+	});
+
+	describe("pauseRecording", () => {
+		it("pauses an active recording", () => {
+			const result = pauseRecording(recorder, true, false, false);
+
+			expect(result).toBe(true);
+			expect(recorder.pause).toHaveBeenCalled();
+			expect(recorder.state).toBe("paused");
+		});
+
+		it("does nothing when already paused", () => {
+			recorder.pause();
+			recorder.pause.mockClear();
+
+			const result = pauseRecording(recorder, true, true, false);
+
+			expect(result).toBe(false);
+			expect(recorder.pause).not.toHaveBeenCalled();
+		});
+
+		it("does nothing when not recording", () => {
+			const result = pauseRecording(recorder, false, false, false);
+
+			expect(result).toBe(false);
+			expect(recorder.pause).not.toHaveBeenCalled();
+		});
+
+		it("does nothing for native recordings", () => {
+			const result = pauseRecording(recorder, true, false, true);
+
+			expect(result).toBe(false);
+			expect(recorder.pause).not.toHaveBeenCalled();
+		});
+	});
+
+	describe("resumeRecording", () => {
+		it("resumes a paused recording", () => {
+			recorder.pause();
+
+			const result = resumeRecording(recorder, true, true);
+
+			expect(result).toBe(true);
+			expect(recorder.resume).toHaveBeenCalled();
+			expect(recorder.state).toBe("recording");
+		});
+
+		it("does nothing when not paused", () => {
+			const result = resumeRecording(recorder, true, false);
+
+			expect(result).toBe(false);
+			expect(recorder.resume).not.toHaveBeenCalled();
+		});
+
+		it("does nothing when not recording", () => {
+			const result = resumeRecording(recorder, false, true);
+
+			expect(result).toBe(false);
+		});
+	});
+
+	describe("pause → stop → editor flow", () => {
+		it("full lifecycle: record → pause → stop completes cleanly", () => {
+			expect(recorder.state).toBe("recording");
+
+			pauseRecording(recorder, true, false, false);
+			expect(recorder.state).toBe("paused");
+
+			const result = stopRecording(recorder, false);
+			expect(result.stopped).toBe(true);
+			expect(recorder.state).toBe("inactive");
+		});
+
+		it("full lifecycle: record → pause → resume → stop completes cleanly", () => {
+			expect(recorder.state).toBe("recording");
+
+			pauseRecording(recorder, true, false, false);
+			expect(recorder.state).toBe("paused");
+
+			resumeRecording(recorder, true, true);
+			expect(recorder.state).toBe("recording");
+
+			const result = stopRecording(recorder, false);
+			expect(result.stopped).toBe(true);
+			expect(recorder.state).toBe("inactive");
+		});
+	});
+});

src/hooks/useScreenRecorder.ts

@@ -185,7 +185,11 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
       return;
     }
 
-    if (mediaRecorder.current?.state === "recording") {
+    const recorderState = mediaRecorder.current?.state;
+    if (recorderState === "recording" || recorderState === "paused") {
+      if (recorderState === "paused") {
+        mediaRecorder.current.resume();
+      }
       cleanupCapturedMedia();
       mediaRecorder.current.stop();
       setRecording(false);
@@ -550,6 +554,8 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 
   const pauseRecording = useCallback(() => {
     if (!recording || paused) return;
+    // Native recordings (macOS SCK / Windows WGC) don't support pause yet
+    if (nativeScreenRecording.current) return;
     if (mediaRecorder.current?.state === "recording") {
       mediaRecorder.current.pause();
       setPaused(true);