feat: add macos screencapturekit helper

electron/electron-env.d.ts

@@ -78,6 +78,13 @@ interface Window {
 			reason?: string;
 			error?: string;
 		}>;
+		isNativeMacCaptureAvailable: () => Promise<{
+			success: boolean;
+			available: boolean;
+			helperPath?: string;
+			reason?: "unsupported-platform" | "missing-helper" | string;
+			error?: string;
+		}>;
 		startNativeWindowsRecording: (
 			request: import("../src/lib/nativeWindowsRecording").NativeWindowsRecordingRequest,
 		) => Promise<import("../src/lib/nativeWindowsRecording").NativeWindowsRecordingStartResult>;
@@ -89,6 +96,17 @@ interface Window {
 			discarded?: boolean;
 			error?: string;
 		}>;
+		startNativeMacRecording: (
+			request: import("../src/lib/nativeMacRecording").NativeMacRecordingRequest,
+		) => Promise<import("../src/lib/nativeMacRecording").NativeMacRecordingStartResult>;
+		stopNativeMacRecording: (discard?: boolean) => Promise<{
+			success: boolean;
+			path?: string;
+			session?: import("../src/lib/recordingSession").RecordingSession;
+			message?: string;
+			discarded?: boolean;
+			error?: string;
+		}>;
 		discardCursorTelemetry: (recordingId: number) => Promise<void>;
 		getCursorTelemetry: (videoPath?: string) => Promise<{
 			success: boolean;

electron/ipc/handlers.ts

@@ -15,6 +15,7 @@ import {
 	shell,
 	systemPreferences,
 } from "electron";
+import type { NativeMacRecordingRequest } from "../../src/lib/nativeMacRecording";
 import type { NativeWindowsRecordingRequest } from "../../src/lib/nativeWindowsRecording";
 import {
 	type CursorCaptureMode,
@@ -276,6 +277,12 @@ let nativeWindowsCaptureRecordingId: number | null = null;
 let nativeWindowsCursorOffsetMs = 0;
 let nativeWindowsCursorCaptureMode: CursorCaptureMode = "editable-overlay";
 const NATIVE_WINDOWS_CAPTURE_STOP_TIMEOUT_MS = 15_000;
+let nativeMacCaptureProcess: ChildProcessWithoutNullStreams | null = null;
+let nativeMacCaptureOutput = "";
+let nativeMacCaptureTargetPath: string | null = null;
+let nativeMacCaptureRecordingId: number | null = null;
+let nativeMacCursorOffsetMs = 0;
+let nativeMacCursorCaptureMode: CursorCaptureMode = "editable-overlay";
 
 function normalizeCursorSample(sample: unknown): CursorRecordingSample | null {
 	if (!sample || typeof sample !== "object") {
@@ -499,6 +506,35 @@ async function findNativeWindowsCaptureHelperPath() {
 	return null;
 }
 
+function getNativeMacCaptureHelperCandidates() {
+	const envPath = process.env.OPENSCREEN_SCK_CAPTURE_EXE?.trim();
+	const archTag = process.arch === "arm64" ? "darwin-arm64" : "darwin-x64";
+	const helperName = "openscreen-screencapturekit-helper";
+	return [
+		envPath,
+		resolveUnpackedAppPath("electron", "native", "screencapturekit", "build", helperName),
+		resolveUnpackedAppPath("electron", "native", "bin", archTag, helperName),
+		resolvePackagedResourcePath("electron", "native", "bin", archTag, helperName),
+	].filter((candidate): candidate is string => Boolean(candidate));
+}
+
+async function findNativeMacCaptureHelperPath() {
+	if (process.platform !== "darwin") {
+		return null;
+	}
+
+	for (const candidate of getNativeMacCaptureHelperCandidates()) {
+		try {
+			await fs.access(candidate, fsConstants.X_OK);
+			return candidate;
+		} catch {
+			// Try the next configured helper location.
+		}
+	}
+
+	return null;
+}
+
 function isWindowsGraphicsCaptureOsSupported() {
 	if (process.platform !== "win32") {
 		return false;
@@ -785,6 +821,134 @@ function readNativeWindowsWebcamFormat(output: string) {
 	}
 }
 
+function tryParseNativeHelperEvent(line: string) {
+	try {
+		const parsed = JSON.parse(line);
+		return parsed && typeof parsed === "object" ? parsed : null;
+	} catch {
+		return null;
+	}
+}
+
+function waitForNativeMacCaptureStart(proc: ChildProcessWithoutNullStreams) {
+	return new Promise<void>((resolve, reject) => {
+		const timer = setTimeout(() => {
+			cleanup();
+			reject(new Error("Timed out waiting for native macOS capture to start"));
+		}, 10_000);
+
+		const inspect = (chunk: Buffer) => {
+			nativeMacCaptureOutput += chunk.toString();
+			for (const line of nativeMacCaptureOutput.split(/\r?\n/)) {
+				const event = tryParseNativeHelperEvent(line.trim());
+				if (!event) continue;
+				if (event.event === "recording-started") {
+					cleanup();
+					resolve();
+					return;
+				}
+				if (event.event === "error") {
+					cleanup();
+					reject(new Error(event.message ?? event.code ?? "Native macOS capture failed"));
+					return;
+				}
+			}
+		};
+
+		const onOutput = (chunk: Buffer) => inspect(chunk);
+		const onClose = (code: number | null) => {
+			cleanup();
+			reject(
+				new Error(
+					nativeMacCaptureOutput.trim() ||
+						`Native macOS capture exited before recording started (code=${code ?? "unknown"})`,
+				),
+			);
+		};
+		const onError = (error: Error) => {
+			cleanup();
+			reject(error);
+		};
+		const cleanup = () => {
+			clearTimeout(timer);
+			proc.stdout.off("data", onOutput);
+			proc.stderr.off("data", onOutput);
+			proc.off("close", onClose);
+			proc.off("error", onError);
+		};
+
+		proc.stdout.on("data", onOutput);
+		proc.stderr.on("data", onOutput);
+		proc.once("close", onClose);
+		proc.once("error", onError);
+	});
+}
+
+function waitForNativeMacCaptureStop(proc: ChildProcessWithoutNullStreams) {
+	return new Promise<string>((resolve, reject) => {
+		const timer = setTimeout(() => {
+			cleanup();
+			reject(
+				new Error(
+					`Timed out waiting for native macOS capture to stop. Output path: ${
+						nativeMacCaptureTargetPath ?? "unknown"
+					}. Output: ${nativeMacCaptureOutput.trim()}`,
+				),
+			);
+		}, 30_000);
+
+		const inspect = (chunk: Buffer) => {
+			nativeMacCaptureOutput += chunk.toString();
+			for (const line of nativeMacCaptureOutput.split(/\r?\n/)) {
+				const event = tryParseNativeHelperEvent(line.trim());
+				if (!event) continue;
+				if (event.event === "recording-stopped") {
+					cleanup();
+					resolve(event.screenPath ?? nativeMacCaptureTargetPath ?? "");
+					return;
+				}
+				if (event.event === "error") {
+					cleanup();
+					reject(new Error(event.message ?? event.code ?? "Native macOS capture failed"));
+					return;
+				}
+			}
+		};
+
+		const onOutput = (chunk: Buffer) => inspect(chunk);
+		const onClose = (code: number | null) => {
+			if (code === 0 && nativeMacCaptureTargetPath) {
+				cleanup();
+				resolve(nativeMacCaptureTargetPath);
+				return;
+			}
+			cleanup();
+			reject(
+				new Error(
+					nativeMacCaptureOutput.trim() ||
+						`Native macOS capture exited with code=${code ?? "unknown"}`,
+				),
+			);
+		};
+		const onError = (error: Error) => {
+			cleanup();
+			reject(error);
+		};
+		const cleanup = () => {
+			clearTimeout(timer);
+			proc.stdout.off("data", onOutput);
+			proc.stderr.off("data", onOutput);
+			proc.off("close", onClose);
+			proc.off("error", onError);
+		};
+
+		proc.stdout.on("data", onOutput);
+		proc.stderr.on("data", onOutput);
+		proc.once("close", onClose);
+		proc.once("error", onError);
+	});
+}
+
 function setCurrentRecordingSessionState(session: RecordingSession | null) {
 	currentRecordingSession = session;
 	currentVideoPath = session?.screenVideoPath ?? null;
@@ -1041,6 +1205,17 @@ export function registerIpcHandlers(
 			: { success: true, available: false, reason: "missing-helper" };
 	});
 
+	ipcMain.handle("is-native-mac-capture-available", async () => {
+		if (process.platform !== "darwin") {
+			return { success: true, available: false, reason: "unsupported-platform" };
+		}
+
+		const helperPath = await findNativeMacCaptureHelperPath();
+		return helperPath
+			? { success: true, available: true, helperPath }
+			: { success: true, available: false, reason: "missing-helper" };
+	});
+
 	ipcMain.handle(
 		"start-native-windows-recording",
 		async (_, request: NativeWindowsRecordingRequest) => {
@@ -1217,6 +1392,121 @@ export function registerIpcHandlers(
 		},
 	);
 
+	ipcMain.handle("start-native-mac-recording", async (_, request: NativeMacRecordingRequest) => {
+		try {
+			if (process.platform !== "darwin") {
+				return { success: false, error: "Native macOS capture requires macOS." };
+			}
+			if (nativeMacCaptureProcess) {
+				return { success: false, error: "Native macOS capture is already running." };
+			}
+
+			const helperPath = await findNativeMacCaptureHelperPath();
+			if (!helperPath) {
+				return { success: false, error: "Native macOS capture helper is not available." };
+			}
+
+			if (!request?.source?.sourceId) {
+				return { success: false, error: "Native macOS capture request is missing a source." };
+			}
+
+			const recordingId =
+				typeof request.recordingId === "number" && Number.isFinite(request.recordingId)
+					? request.recordingId
+					: Date.now();
+			const outputPath = path.join(RECORDINGS_DIR, `${RECORDING_FILE_PREFIX}${recordingId}.mp4`);
+			const cursorCaptureMode =
+				normalizeCursorCaptureMode(request.cursor?.mode) ?? "editable-overlay";
+			const sourceDisplay =
+				request.source.type === "display" && typeof request.source.displayId === "number"
+					? (screen.getAllDisplays().find((display) => display.id === request.source.displayId) ??
+						null)
+					: getSelectedDisplay();
+			const bounds = request.source.bounds ?? sourceDisplay?.bounds ?? getSelectedSourceBounds();
+			const config: NativeMacRecordingRequest = {
+				...request,
+				schemaVersion: 1,
+				recordingId,
+				source: {
+					...request.source,
+					bounds,
+				},
+				video: {
+					...request.video,
+					hideSystemCursor: cursorCaptureMode === "editable-overlay",
+				},
+				cursor: {
+					mode: cursorCaptureMode,
+				},
+				outputs: {
+					screenPath: outputPath,
+					manifestPath: path.join(
+						RECORDINGS_DIR,
+						`${RECORDING_FILE_PREFIX}${recordingId}${RECORDING_SESSION_SUFFIX}`,
+					),
+				},
+			};
+
+			console.info("[native-sck] starting macOS capture", {
+				helperPath,
+				source: config.source,
+				audio: config.audio,
+				webcam: config.webcam,
+				cursor: config.cursor,
+				outputPath,
+			});
+
+			await fs.mkdir(RECORDINGS_DIR, { recursive: true });
+			nativeMacCaptureOutput = "";
+			nativeMacCaptureTargetPath = outputPath;
+			nativeMacCaptureRecordingId = recordingId;
+			nativeMacCursorOffsetMs = 0;
+			nativeMacCursorCaptureMode = cursorCaptureMode;
+
+			const cursorStartTimeMs = Date.now();
+			if (cursorCaptureMode === "editable-overlay") {
+				await startCursorRecording(cursorStartTimeMs);
+			} else {
+				pendingCursorRecordingData = null;
+			}
+
+			const proc = spawn(helperPath, [JSON.stringify(config)], {
+				cwd: RECORDINGS_DIR,
+				stdio: ["pipe", "pipe", "pipe"],
+			});
+			nativeMacCaptureProcess = proc;
+
+			await waitForNativeMacCaptureStart(proc);
+			const captureStartedAtMs = Date.now();
+			nativeMacCursorOffsetMs =
+				cursorCaptureMode === "editable-overlay"
+					? Math.max(0, captureStartedAtMs - cursorStartTimeMs)
+					: 0;
+
+			const source = selectedSource || { name: "Screen" };
+			if (onRecordingStateChange) {
+				onRecordingStateChange(true, source.name);
+			}
+
+			return {
+				success: true,
+				recordingId,
+				path: outputPath,
+				helperPath,
+			};
+		} catch (error) {
+			console.error("Failed to start native macOS recording:", error);
+			nativeMacCaptureProcess?.kill();
+			nativeMacCaptureProcess = null;
+			nativeMacCaptureTargetPath = null;
+			nativeMacCaptureRecordingId = null;
+			nativeMacCursorOffsetMs = 0;
+			nativeMacCursorCaptureMode = "editable-overlay";
+			await stopCursorRecording();
+			return { success: false, error: error instanceof Error ? error.message : String(error) };
+		}
+	});
+
 	ipcMain.handle("stop-native-windows-recording", async (_, discard?: boolean) => {
 		const proc = nativeWindowsCaptureProcess;
 		const preferredPath = nativeWindowsCaptureTargetPath;
@@ -1301,6 +1591,81 @@ export function registerIpcHandlers(
 		}
 	});
 
+	ipcMain.handle("stop-native-mac-recording", async (_, discard?: boolean) => {
+		const proc = nativeMacCaptureProcess;
+		const preferredPath = nativeMacCaptureTargetPath;
+		const recordingId = nativeMacCaptureRecordingId ?? Date.now();
+		const cursorCaptureMode = nativeMacCursorCaptureMode;
+
+		if (!proc) {
+			return { success: false, error: "Native macOS capture is not running." };
+		}
+
+		try {
+			const stoppedPathPromise = waitForNativeMacCaptureStop(proc);
+			proc.stdin.write("stop\n");
+			const stoppedPath = await stoppedPathPromise;
+			const screenVideoPath = stoppedPath || preferredPath;
+			if (!screenVideoPath) {
+				throw new Error("Native macOS capture did not return an output path.");
+			}
+
+			if (cursorCaptureMode === "editable-overlay") {
+				await stopCursorRecording();
+			} else {
+				pendingCursorRecordingData = null;
+			}
+			if (discard) {
+				pendingCursorRecordingData = null;
+				await Promise.all([
+					fs.rm(screenVideoPath, { force: true }),
+					fs.rm(`${screenVideoPath}.cursor.json`, { force: true }),
+				]);
+				return { success: true, discarded: true };
+			}
+
+			if (cursorCaptureMode === "editable-overlay") {
+				shiftPendingCursorTelemetry(nativeMacCursorOffsetMs);
+				await writePendingCursorTelemetry(screenVideoPath);
+			}
+
+			const session: RecordingSession = {
+				screenVideoPath,
+				createdAt: recordingId,
+				cursorCaptureMode,
+			};
+			setCurrentRecordingSessionState(session);
+			currentProjectPath = null;
+
+			const sessionManifestPath = path.join(
+				RECORDINGS_DIR,
+				`${path.parse(screenVideoPath).name}${RECORDING_SESSION_SUFFIX}`,
+			);
+			await fs.writeFile(sessionManifestPath, JSON.stringify(session, null, 2), "utf-8");
+
+			return {
+				success: true,
+				path: screenVideoPath,
+				session,
+				message: "Native macOS recording session stored successfully",
+			};
+		} catch (error) {
+			console.error("Failed to stop native macOS recording:", error);
+			await stopCursorRecording();
+			return { success: false, error: error instanceof Error ? error.message : String(error) };
+		} finally {
+			nativeMacCaptureProcess = null;
+			nativeMacCaptureTargetPath = null;
+			nativeMacCaptureRecordingId = null;
+			nativeMacCursorOffsetMs = 0;
+			nativeMacCursorCaptureMode = "editable-overlay";
+			const source = selectedSource || { name: "Screen" };
+			if (onRecordingStateChange) {
+				onRecordingStateChange(false, source.name);
+			}
+		}
+	});
+
 	ipcMain.handle("store-recorded-session", async (_, payload: StoreRecordedSessionInput) => {
 		try {
 			return await storeRecordedSessionFiles(payload);

electron/native/README.md

@@ -9,19 +9,23 @@ macOS native recording will use a ScreenCaptureKit helper with the same process
 3. The helper owns ScreenCaptureKit/AVFoundation capture, timing, encoding, and muxing.
 4. Electron persists the resulting media/session manifest and reports helper errors explicitly.
 
-Expected development helper locations:
+Helper locations:
 
 1. `OPENSCREEN_SCK_CAPTURE_EXE`, for local development and diagnostics.
 2. `electron/native/screencapturekit/build/openscreen-screencapturekit-helper`, for locally built Swift output.
 3. `electron/native/bin/darwin-arm64/openscreen-screencapturekit-helper` or `electron/native/bin/darwin-x64/openscreen-screencapturekit-helper`, for packaged prebuilt helpers.
 
-The current macOS helper script is a placeholder:
+Build the macOS helper with:
 
 ```bash
 npm run build:native:mac
 ```
 
-On non-macOS hosts this command exits successfully and does not affect Windows/Linux development. On macOS it fails until the Swift ScreenCaptureKit helper lands.
+On non-macOS hosts this command exits successfully and does not affect Windows/Linux development. On macOS it builds the Swift package at `electron/native/screencapturekit`, writes the development binary to `electron/native/screencapturekit/build/openscreen-screencapturekit-helper`, and copies the redistributable binary to `electron/native/bin/darwin-${arch}/openscreen-screencapturekit-helper`.
+
+The current helper implementation supports the first native media slice: display/window ScreenCaptureKit video capture, cursor exclusion through `SCStreamConfiguration.showsCursor`, H.264 encoding, and MP4 muxing. System audio, microphone capture, webcam composition, and runtime controls are intentionally left as explicit roadmap phases.
+
+Electron exposes `is-native-mac-capture-available` for capability probing. It resolves the same helper locations listed above and reports `missing-helper` until a Swift helper binary is present; production recording is not routed through the macOS helper yet.
 
 See `docs/engineering/macos-native-recorder-roadmap.md` for the contract, rollout phases, and SSOT rules.
 

electron/native/screencapturekit/Package.swift

@@ -0,0 +1,22 @@
+// swift-tools-version: 5.9
+
+import PackageDescription
+
+let package = Package(
+	name: "OpenScreenScreenCaptureKitHelper",
+	platforms: [
+		.macOS(.v13)
+	],
+	products: [
+		.executable(
+			name: "openscreen-screencapturekit-helper",
+			targets: ["OpenScreenScreenCaptureKitHelper"]
+		)
+	],
+	targets: [
+		.executableTarget(
+			name: "OpenScreenScreenCaptureKitHelper",
+			path: "Sources/OpenScreenScreenCaptureKitHelper"
+		)
+	]
+)

electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/main.swift

@@ -0,0 +1,355 @@
+import AVFoundation
+import CoreMedia
+import Foundation
+import ScreenCaptureKit
+
+struct Rectangle: Decodable {
+	let x: Double
+	let y: Double
+	let width: Double
+	let height: Double
+}
+
+struct RecordingRequest: Decodable {
+	struct Source: Decodable {
+		let type: String
+		let sourceId: String
+		let displayId: UInt32?
+		let windowId: UInt32?
+		let bounds: Rectangle?
+	}
+
+	struct Video: Decodable {
+		let fps: Int
+		let width: Int
+		let height: Int
+		let bitrate: Int?
+		let hideSystemCursor: Bool
+	}
+
+	struct Audio: Decodable {
+		struct SystemAudio: Decodable {
+			let enabled: Bool
+		}
+
+		struct Microphone: Decodable {
+			let enabled: Bool
+			let deviceId: String?
+			let deviceName: String?
+			let gain: Double
+		}
+
+		let system: SystemAudio
+		let microphone: Microphone
+	}
+
+	struct Webcam: Decodable {
+		let enabled: Bool
+		let deviceId: String?
+		let deviceName: String?
+		let width: Int
+		let height: Int
+		let fps: Int
+	}
+
+	struct Cursor: Decodable {
+		let mode: String
+	}
+
+	struct Outputs: Decodable {
+		let screenPath: String
+		let manifestPath: String?
+	}
+
+	let schemaVersion: Int?
+	let recordingId: Int?
+	let source: Source
+	let video: Video
+	let audio: Audio
+	let webcam: Webcam
+	let cursor: Cursor
+	let outputs: Outputs
+}
+
+enum HelperError: Error, CustomStringConvertible {
+	case invalidArguments
+	case unsupportedMacOS
+	case unsupportedFeature(String)
+	case sourceNotFound(String)
+	case invalidSourceType(String)
+	case writerSetupFailed(String)
+
+	var description: String {
+		switch self {
+		case .invalidArguments:
+			return "Expected one JSON recording request argument."
+		case .unsupportedMacOS:
+			return "ScreenCaptureKit recording requires macOS 13 or newer."
+		case .unsupportedFeature(let message):
+			return message
+		case .sourceNotFound(let message):
+			return message
+		case .invalidSourceType(let sourceType):
+			return "Unsupported source type: \(sourceType)."
+		case .writerSetupFailed(let message):
+			return message
+		}
+	}
+}
+
+func emit(_ fields: [String: Any]) {
+	if let data = try? JSONSerialization.data(withJSONObject: fields, options: []),
+		let line = String(data: data, encoding: .utf8)
+	{
+		print(line)
+		fflush(stdout)
+	}
+}
+
+func emitError(code: String, message: String) {
+	emit([
+		"event": "error",
+		"code": code,
+		"message": message,
+	])
+}
+
+@available(macOS 13.0, *)
+final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
+	private let request: RecordingRequest
+	private let sampleQueue = DispatchQueue(label: "app.openscreen.sck-helper.samples")
+	private let stateQueue = DispatchQueue(label: "app.openscreen.sck-helper.state")
+	private var stream: SCStream?
+	private var writer: AVAssetWriter?
+	private var videoInput: AVAssetWriterInput?
+	private var didStartWriting = false
+	private var isStopping = false
+
+	init(request: RecordingRequest) {
+		self.request = request
+	}
+
+	func start() async throws {
+		try rejectUnsupportedPhaseFeatures()
+
+		let content = try await SCShareableContent.excludingDesktopWindows(
+			false,
+			onScreenWindowsOnly: true
+		)
+		let filter = try makeContentFilter(from: content)
+		let configuration = makeStreamConfiguration()
+		let stream = SCStream(filter: filter, configuration: configuration, delegate: self)
+
+		try stream.addStreamOutput(self, type: .screen, sampleHandlerQueue: sampleQueue)
+		try setupWriter()
+
+		self.stream = stream
+		emit(["event": "ready", "schemaVersion": 1])
+		try await stream.startCapture()
+		emit([
+			"event": "recording-started",
+			"timestampMs": Int(Date().timeIntervalSince1970 * 1000),
+		])
+	}
+
+	func stop() async {
+		let shouldStop = stateQueue.sync {
+			if isStopping {
+				return false
+			}
+			isStopping = true
+			return true
+		}
+		if !shouldStop {
+			return
+		}
+
+		do {
+			try await stream?.stopCapture()
+		} catch {
+			emit([
+				"event": "warning",
+				"code": "stop-capture-failed",
+				"message": "\(error)",
+			])
+		}
+
+		await finishWriter()
+	}
+
+	func stream(_ stream: SCStream, didStopWithError error: Error) {
+		emitError(code: "capture-stopped-with-error", message: "\(error)")
+		Task {
+			await stop()
+		}
+	}
+
+	func stream(_ stream: SCStream, didOutputSampleBuffer sampleBuffer: CMSampleBuffer, of type: SCStreamOutputType) {
+		guard type == .screen else {
+			return
+		}
+		guard CMSampleBufferDataIsReady(sampleBuffer) else {
+			return
+		}
+		guard let videoInput, let writer else {
+			return
+		}
+
+		let presentationTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
+		if !didStartWriting {
+			writer.startWriting()
+			writer.startSession(atSourceTime: presentationTime)
+			didStartWriting = true
+		}
+
+		if videoInput.isReadyForMoreMediaData {
+			videoInput.append(sampleBuffer)
+		}
+	}
+
+	private func rejectUnsupportedPhaseFeatures() throws {
+		if request.audio.system.enabled {
+			throw HelperError.unsupportedFeature(
+				"System audio capture is planned for the roadmap system-audio phase."
+			)
+		}
+		if request.audio.microphone.enabled {
+			throw HelperError.unsupportedFeature(
+				"Microphone capture is planned for the roadmap microphone phase."
+			)
+		}
+		if request.webcam.enabled {
+			throw HelperError.unsupportedFeature(
+				"Webcam composition is planned for the roadmap webcam phase."
+			)
+		}
+	}
+
+	private func makeContentFilter(from content: SCShareableContent) throws -> SCContentFilter {
+		switch request.source.type {
+		case "display":
+			guard let displayId = request.source.displayId else {
+				throw HelperError.sourceNotFound("Display capture requires source.displayId.")
+			}
+			guard let display = content.displays.first(where: { $0.displayID == displayId }) else {
+				throw HelperError.sourceNotFound("No ScreenCaptureKit display found for id \(displayId).")
+			}
+			return SCContentFilter(display: display, excludingWindows: [])
+		case "window":
+			guard let windowId = request.source.windowId else {
+				throw HelperError.sourceNotFound("Window capture requires source.windowId.")
+			}
+			guard let window = content.windows.first(where: { $0.windowID == windowId }) else {
+				throw HelperError.sourceNotFound("No ScreenCaptureKit window found for id \(windowId).")
+			}
+			return SCContentFilter(desktopIndependentWindow: window)
+		default:
+			throw HelperError.invalidSourceType(request.source.type)
+		}
+	}
+
+	private func makeStreamConfiguration() -> SCStreamConfiguration {
+		let configuration = SCStreamConfiguration()
+		configuration.width = request.video.width
+		configuration.height = request.video.height
+		configuration.minimumFrameInterval = CMTime(value: 1, timescale: CMTimeScale(max(1, request.video.fps)))
+		configuration.queueDepth = 6
+		configuration.showsCursor = !request.video.hideSystemCursor
+		configuration.pixelFormat = kCVPixelFormatType_32BGRA
+		return configuration
+	}
+
+	private func setupWriter() throws {
+		let outputUrl = URL(fileURLWithPath: request.outputs.screenPath)
+		try? FileManager.default.removeItem(at: outputUrl)
+		try FileManager.default.createDirectory(
+			at: outputUrl.deletingLastPathComponent(),
+			withIntermediateDirectories: true
+		)
+
+		let writer = try AVAssetWriter(outputURL: outputUrl, fileType: .mp4)
+		let settings: [String: Any] = [
+			AVVideoCodecKey: AVVideoCodecType.h264,
+			AVVideoWidthKey: request.video.width,
+			AVVideoHeightKey: request.video.height,
+			AVVideoCompressionPropertiesKey: [
+				AVVideoAverageBitRateKey: request.video.bitrate ?? 18_000_000,
+				AVVideoExpectedSourceFrameRateKey: request.video.fps,
+			],
+		]
+		let input = AVAssetWriterInput(mediaType: .video, outputSettings: settings)
+		input.expectsMediaDataInRealTime = true
+
+		guard writer.canAdd(input) else {
+			throw HelperError.writerSetupFailed("Unable to add H.264 video input to AVAssetWriter.")
+		}
+
+		writer.add(input)
+		self.writer = writer
+		self.videoInput = input
+	}
+
+	private func finishWriter() async {
+		guard let writer else {
+			return
+		}
+
+		videoInput?.markAsFinished()
+
+		await withCheckedContinuation { continuation in
+			writer.finishWriting {
+				continuation.resume()
+			}
+		}
+
+		if writer.status == .completed {
+			emit([
+				"event": "recording-stopped",
+				"screenPath": request.outputs.screenPath,
+			])
+		} else {
+			emitError(
+				code: "writer-failed",
+				message: writer.error.map { "\($0)" } ?? "AVAssetWriter failed with status \(writer.status.rawValue)."
+			)
+		}
+	}
+}
+
+@main
+struct OpenScreenScreenCaptureKitHelper {
+	static func main() async {
+		do {
+			guard CommandLine.arguments.count == 2 else {
+				throw HelperError.invalidArguments
+			}
+
+			guard #available(macOS 13.0, *) else {
+				throw HelperError.unsupportedMacOS
+			}
+
+			let requestData = Data(CommandLine.arguments[1].utf8)
+			let decoder = JSONDecoder()
+			let request = try decoder.decode(RecordingRequest.self, from: requestData)
+			let recorder = ScreenCaptureRecorder(request: request)
+			let stopTask = Task.detached {
+				while let line = readLine() {
+					let command = line.trimmingCharacters(in: .whitespacesAndNewlines)
+					if command == "stop" {
+						await recorder.stop()
+						exit(0)
+					}
+				}
+			}
+
+			try await recorder.start()
+			await stopTask.value
+		} catch let error as HelperError {
+			emitError(code: "helper-error", message: error.description)
+			exit(1)
+		} catch {
+			emitError(code: "helper-error", message: "\(error)")
+			exit(1)
+		}
+	}
+}

electron/preload.ts

@@ -1,4 +1,5 @@
 import { contextBridge, ipcRenderer } from "electron";
+import type { NativeMacRecordingRequest } from "../src/lib/nativeMacRecording";
 import type { NativeWindowsRecordingRequest } from "../src/lib/nativeWindowsRecording";
 import type { RecordingSession, StoreRecordedSessionInput } from "../src/lib/recordingSession";
 import { NATIVE_BRIDGE_CHANNEL, type NativeBridgeRequest } from "../src/native/contracts";
@@ -68,12 +69,21 @@ contextBridge.exposeInMainWorld("electronAPI", {
 	isNativeWindowsCaptureAvailable: () => {
 		return ipcRenderer.invoke("is-native-windows-capture-available");
 	},
+	isNativeMacCaptureAvailable: () => {
+		return ipcRenderer.invoke("is-native-mac-capture-available");
+	},
 	startNativeWindowsRecording: (request: NativeWindowsRecordingRequest) => {
 		return ipcRenderer.invoke("start-native-windows-recording", request);
 	},
 	stopNativeWindowsRecording: (discard?: boolean) => {
 		return ipcRenderer.invoke("stop-native-windows-recording", discard);
 	},
+	startNativeMacRecording: (request: NativeMacRecordingRequest) => {
+		return ipcRenderer.invoke("start-native-mac-recording", request);
+	},
+	stopNativeMacRecording: (discard?: boolean) => {
+		return ipcRenderer.invoke("stop-native-mac-recording", discard);
+	},
 	getCursorTelemetry: (videoPath?: string) => {
 		return ipcRenderer.invoke("get-cursor-telemetry", videoPath);
 	},

scripts/build-macos-screencapturekit-helper.mjs

@@ -1,13 +1,75 @@
 #!/usr/bin/env node
 
+import { spawnSync } from "node:child_process";
+import fs from "node:fs";
+import path from "node:path";
 import process from "node:process";
+import { fileURLToPath } from "node:url";
 
 if (process.platform !== "darwin") {
 	console.log("Skipping macOS ScreenCaptureKit helper build: host platform is not macOS.");
 	process.exit(0);
 }
 
-console.error(
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
-	"macOS ScreenCaptureKit helper sources are not implemented yet. See docs/engineering/macos-native-recorder-roadmap.md.",
+const root = path.resolve(__dirname, "..");
+const helperName = "openscreen-screencapturekit-helper";
+const packageDir = path.join(root, "electron", "native", "screencapturekit");
+const buildDir = path.join(packageDir, "build");
+const swiftBuildDir = path.join(buildDir, "swiftpm");
+const builtHelperPath = path.join(swiftBuildDir, "release", helperName);
+const localHelperPath = path.join(buildDir, helperName);
+const archTag = process.arch === "arm64" ? "darwin-arm64" : "darwin-x64";
+const distributableDir = path.join(root, "electron", "native", "bin", archTag);
+const distributablePath = path.join(distributableDir, helperName);
+
+const xcodebuildVersion = spawnSync("xcodebuild", ["-version"], {
+	cwd: root,
+	encoding: "utf8",
+});
+
+if (xcodebuildVersion.status !== 0) {
+	const message = `${xcodebuildVersion.stderr ?? ""}${xcodebuildVersion.stdout ?? ""}`.trim();
+	console.error(
+		[
+			"Unable to build the macOS ScreenCaptureKit helper because full Xcode is not active.",
+			"",
+			message,
+			"",
+			"Install Xcode from the App Store or Apple Developer downloads, then run:",
+			"  sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer",
+			"  sudo xcodebuild -license accept",
+			"",
+			"Command Line Tools alone may not include the Swift SDK/platform metadata required by SwiftPM.",
+		].join("\n"),
+	);
+	process.exit(1);
+}
+
+const result = spawnSync(
+	"swift",
+	["build", "-c", "release", "--package-path", packageDir, "--build-path", swiftBuildDir],
+	{
+		cwd: root,
+		stdio: "inherit",
+	},
 );
-process.exit(1);
+
+if (result.error) {
+	console.error(`Failed to start Swift build: ${result.error.message}`);
+	process.exit(1);
+}
+
+if (result.status !== 0) {
+	process.exit(result.status ?? 1);
+}
+
+fs.mkdirSync(buildDir, { recursive: true });
+fs.mkdirSync(distributableDir, { recursive: true });
+fs.copyFileSync(builtHelperPath, localHelperPath);
+fs.copyFileSync(builtHelperPath, distributablePath);
+fs.chmodSync(localHelperPath, 0o755);
+fs.chmodSync(distributablePath, 0o755);
+
+console.log(`Built macOS ScreenCaptureKit helper: ${localHelperPath}`);
+console.log(`Copied redistributable helper: ${distributablePath}`);

src/components/launch/LaunchWindow.tsx

@@ -127,7 +127,7 @@ export function LaunchWindow() {
 	const [isWebcamFocused, setIsWebcamFocused] = useState(false);
 	const webcamExpanded = isWebcamHovered || isWebcamFocused;
 	const [isLanguageMenuOpen, setIsLanguageMenuOpen] = useState(false);
-	const [isWindows, setIsWindows] = useState(false);
+	const [supportsCursorModeToggle, setSupportsCursorModeToggle] = useState(false);
 	const languageTriggerRef = useRef<HTMLButtonElement | null>(null);
 	const languageMenuPanelRef = useRef<HTMLDivElement | null>(null);
 	const [languageMenuStyle, setLanguageMenuStyle] = useState<{
@@ -192,12 +192,12 @@ export function LaunchWindow() {
 			.getPlatform()
 			.then((platform) => {
 				if (!cancelled) {
-					setIsWindows(platform === "win32");
+					setSupportsCursorModeToggle(platform === "win32" || platform === "darwin");
 				}
 			})
 			.catch(() => {
 				if (!cancelled) {
-					setIsWindows(false);
+					setSupportsCursorModeToggle(false);
 				}
 			});
 
@@ -609,7 +609,7 @@ export function LaunchWindow() {
 							? getIcon("webcamOn", "text-green-400")
 							: getIcon("webcamOff", "text-white/40")}
 					</button>
-					{isWindows && (
+					{supportsCursorModeToggle && (
 						<button
 							data-testid="launch-cursor-mode-button"
 							className={`${hudIconBtnClasses} ${

src/hooks/useScreenRecorder.ts

@@ -2,6 +2,11 @@ import { fixWebmDuration } from "@fix-webm-duration/fix";
 import { useCallback, useEffect, useRef, useState } from "react";
 import { toast } from "sonner";
 import { useScopedT } from "@/contexts/I18nContext";
+import {
+	type NativeMacRecordingRequest,
+	parseMacDisplayIdFromSourceId,
+	parseMacWindowIdFromSourceId,
+} from "@/lib/nativeMacRecording";
 import {
 	type NativeWindowsRecordingRequest,
 	parseWindowHandleFromSourceId,
@@ -80,6 +85,11 @@ type NativeWindowsRecordingHandle = {
 	finalizing: boolean;
 };
 
+type NativeMacRecordingHandle = {
+	recordingId: number;
+	finalizing: boolean;
+};
+
 function createRecorderHandle(stream: MediaStream, options: MediaRecorderOptions): RecorderHandle {
 	const recorder = new MediaRecorder(stream, options);
 	const chunks: Blob[] = [];
@@ -118,6 +128,7 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 	const screenRecorder = useRef<RecorderHandle | null>(null);
 	const webcamRecorder = useRef<RecorderHandle | null>(null);
 	const nativeWindowsRecording = useRef<NativeWindowsRecordingHandle | null>(null);
+	const nativeMacRecording = useRef<NativeMacRecordingHandle | null>(null);
 	const stream = useRef<MediaStream | null>(null);
 	const screenStream = useRef<MediaStream | null>(null);
 	const microphoneStream = useRef<MediaStream | null>(null);
@@ -455,11 +466,66 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 		}
 	}, []);
 
+	const finalizeNativeMacRecording = useCallback(async (discard = false) => {
+		const activeNativeRecording = nativeMacRecording.current;
+		if (!activeNativeRecording || activeNativeRecording.finalizing) {
+			return false;
+		}
+
+		activeNativeRecording.finalizing = true;
+
+		const clearNativeRecordingState = () => {
+			nativeMacRecording.current = null;
+			setRecording(false);
+			setPaused(false);
+			setElapsedSeconds(0);
+			accumulatedDurationMs.current = 0;
+			segmentStartedAt.current = null;
+		};
+
+		try {
+			const result = await window.electronAPI.stopNativeMacRecording(discard);
+			if (discard || result.discarded) {
+				clearNativeRecordingState();
+				return true;
+			}
+			if (!result.success) {
+				console.error("Failed to stop native macOS recording:", result.error);
+				toast.error(result.error ?? "Failed to stop native macOS recording");
+				activeNativeRecording.finalizing = false;
+				return true;
+			}
+
+			clearNativeRecordingState();
+			if (result.session) {
+				await window.electronAPI.setCurrentRecordingSession(result.session);
+			} else if (result.path) {
+				await window.electronAPI.setCurrentVideoPath(result.path);
+			}
+
+			await window.electronAPI.switchToEditor();
+			return true;
+		} catch (error) {
+			console.error("Error saving native macOS recording:", error);
+			toast.error(error instanceof Error ? error.message : "Failed to save native macOS recording");
+			activeNativeRecording.finalizing = false;
+			return true;
+		} finally {
+			if (discardRecordingId.current === activeNativeRecording.recordingId) {
+				discardRecordingId.current = null;
+			}
+		}
+	}, []);
+
 	const stopRecording = useRef(() => {
 		if (nativeWindowsRecording.current) {
 			void finalizeNativeWindowsRecording(false);
 			return;
 		}
+		if (nativeMacRecording.current) {
+			void finalizeNativeMacRecording(false);
+			return;
+		}
 
 		const activeScreenRecorder = screenRecorder.current;
 		if (!activeScreenRecorder) {
@@ -529,6 +595,9 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			if (nativeWindowsRecording.current) {
 				void finalizeNativeWindowsRecording(true);
 			}
+			if (nativeMacRecording.current) {
+				void finalizeNativeMacRecording(true);
+			}
 
 			if (
 				screenRecorder.current?.recorder.state === "recording" ||
@@ -554,7 +623,12 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			webcamRecorder.current = null;
 			teardownMedia();
 		};
-	}, [teardownMedia, safeHideCountdownOverlay, finalizeNativeWindowsRecording]);
+	}, [
+		teardownMedia,
+		safeHideCountdownOverlay,
+		finalizeNativeWindowsRecording,
+		finalizeNativeMacRecording,
+	]);
 
 	const safeShowCountdownOverlay = async (value: number, runId: number) => {
 		try {
@@ -677,6 +751,106 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 		}
 	};
 
+	const startNativeMacRecordingIfAvailable = async (
+		selectedSource: ProcessedDesktopSource,
+		countdownRunToken?: number,
+	) => {
+		try {
+			const platform = await window.electronAPI.getPlatform();
+			if (platform !== "darwin") {
+				return false;
+			}
+
+			const availability = await window.electronAPI.isNativeMacCaptureAvailable();
+			if (!availability.success || !availability.available) {
+				if (availability.reason === "unsupported-platform") {
+					return false;
+				}
+
+				throw new Error(
+					availability.reason === "missing-helper"
+						? "Native macOS capture helper is not available."
+						: (availability.error ?? "Native macOS capture is not available."),
+				);
+			}
+
+			if (!isCountdownRunActive(countdownRunToken)) {
+				return true;
+			}
+
+			const activeRecordingId = Date.now();
+			const sourceType = selectedSource.id.startsWith("window:") ? "window" : "display";
+			const displayId =
+				Number(selectedSource.display_id) || parseMacDisplayIdFromSourceId(selectedSource.id);
+			const windowId = parseMacWindowIdFromSourceId(selectedSource.id);
+			if (webcamEnabled) {
+				stopWebcamPreviewStream();
+			}
+			const request: NativeMacRecordingRequest = {
+				schemaVersion: 1,
+				recordingId: activeRecordingId,
+				source: {
+					type: sourceType,
+					sourceId: selectedSource.id,
+					...(displayId ? { displayId } : {}),
+					...(windowId ? { windowId } : {}),
+				},
+				video: {
+					fps: TARGET_FRAME_RATE,
+					width: TARGET_WIDTH,
+					height: TARGET_HEIGHT,
+					bitrate: computeBitrate(TARGET_WIDTH, TARGET_HEIGHT),
+					hideSystemCursor: cursorCaptureMode === "editable-overlay",
+				},
+				audio: {
+					system: {
+						enabled: systemAudioEnabled,
+					},
+					microphone: {
+						enabled: microphoneEnabled,
+						deviceId: microphoneDeviceId,
+						deviceName: microphoneDeviceName,
+						gain: MIC_GAIN_BOOST,
+					},
+				},
+				webcam: {
+					enabled: webcamEnabled,
+					deviceId: webcamDeviceId,
+					deviceName: webcamDeviceName,
+					width: WEBCAM_TARGET_WIDTH,
+					height: WEBCAM_TARGET_HEIGHT,
+					fps: WEBCAM_TARGET_FRAME_RATE,
+				},
+				cursor: {
+					mode: cursorCaptureMode,
+				},
+				outputs: {
+					screenPath: "",
+				},
+			};
+			const result = await window.electronAPI.startNativeMacRecording(request);
+			if (!result.success || !result.recordingId) {
+				throw new Error(result.error ?? "Native macOS capture failed.");
+			}
+
+			recordingId.current = result.recordingId;
+			nativeMacRecording.current = {
+				recordingId: result.recordingId,
+				finalizing: false,
+			};
+			accumulatedDurationMs.current = 0;
+			segmentStartedAt.current = Date.now();
+			allowAutoFinalize.current = true;
+			setRecording(true);
+			setPaused(false);
+			setElapsedSeconds(0);
+			return true;
+		} catch (error) {
+			console.error("Native macOS capture failed:", error);
+			throw error;
+		}
+	};
+
 	const startRecordCountdown = async () => {
 		if (countdownActive || recording) {
 			return;
@@ -767,6 +941,9 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			if (await startNativeWindowsRecordingIfAvailable(selectedSource, countdownRunToken)) {
 				return;
 			}
+			if (await startNativeMacRecordingIfAvailable(selectedSource, countdownRunToken)) {
+				return;
+			}
 
 			let screenMediaStream: MediaStream;
 			const platform = await window.electronAPI.getPlatform();

src/lib/nativeMacRecording.ts

@@ -4,6 +4,7 @@ import type { CursorCaptureMode } from "./recordingSession";
 export type NativeMacSourceType = "display" | "window";
 
 export type NativeMacRecordingRequest = {
+	schemaVersion: 1;
 	recordingId?: number;
 	source: {
 		type: NativeMacSourceType;
@@ -47,6 +48,40 @@ export type NativeMacRecordingRequest = {
 	};
 };
 
+export type NativeMacHelperReadyEvent = {
+	event: "ready";
+	schemaVersion: 1;
+};
+
+export type NativeMacHelperRecordingStartedEvent = {
+	event: "recording-started";
+	timestampMs: number;
+};
+
+export type NativeMacHelperRecordingStoppedEvent = {
+	event: "recording-stopped";
+	screenPath: string;
+};
+
+export type NativeMacHelperWarningEvent = {
+	event: "warning";
+	code: string;
+	message: string;
+};
+
+export type NativeMacHelperErrorEvent = {
+	event: "error";
+	code: string;
+	message: string;
+};
+
+export type NativeMacHelperEvent =
+	| NativeMacHelperReadyEvent
+	| NativeMacHelperRecordingStartedEvent
+	| NativeMacHelperRecordingStoppedEvent
+	| NativeMacHelperWarningEvent
+	| NativeMacHelperErrorEvent;
+
 export type NativeMacRecordingStartResult = {
 	success: boolean;
 	recordingId?: number;

vite.config.ts

@@ -10,6 +10,11 @@ export default defineConfig({
 		electron({
 			main: {
 				entry: "electron/main.ts",
+				onstart({ startup }) {
+					const env = { ...process.env };
+					delete env.ELECTRON_RUN_AS_NODE;
+					return startup(["."], { env });
+				},
 				vite: {
 					build: {},
 				},