fix(macos): correct cursor offset in single-window capture

electron/ipc/handlers.ts

@@ -5,7 +5,7 @@ import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
 import { fileURLToPath, pathToFileURL } from "node:url";
-import type { DesktopCapturerSource } from "electron";
+import type { DesktopCapturerSource, Rectangle } from "electron";
 import {
 	app,
 	BrowserWindow,
@@ -424,6 +424,8 @@ let nativeMacCursorRecordingStartMs = 0;
 let nativeMacPauseStartedAtMs: number | null = null;
 let nativeMacPauseRanges: Array<{ startMs: number; endMs: number }> = [];
 let nativeMacIsPaused = false;
+// Global frame of the region captured by the SCK helper (see getSelectedSourceBounds).
+let activeMacCaptureBounds: Rectangle | null = null;
 
 function normalizeCursorSample(sample: unknown): CursorRecordingSample | null {
 	if (!sample || typeof sample !== "object") {
@@ -573,6 +575,14 @@ function resolveAssetBasePath() {
 }
 
 function getSelectedSourceBounds() {
+	// Single-window capture records only the window's region, not the whole display.
+	// Normalizing the cursor against display bounds leaves a fixed offset in the export,
+	// so prefer the helper-reported window frame when capturing a window.
+	const isWindowSource = selectedSource?.id?.startsWith("window:") === true;
+	if (isWindowSource && activeMacCaptureBounds) {
+		return activeMacCaptureBounds;
+	}
+
 	const cursor = screen.getCursorScreenPoint();
 	const sourceDisplayId = Number(selectedSource?.display_id);
 	const sourceDisplay = Number.isFinite(sourceDisplayId)
@@ -1039,11 +1049,19 @@ function tryParseNativeHelperEvent(line: string) {
 	}
 }
 
+function dispatchNativeMacHelperEvent(event: Record<string, unknown>) {
+	const bounds = event.captureBounds as Rectangle | undefined;
+	if (bounds && bounds.width > 0 && bounds.height > 0) {
+		activeMacCaptureBounds = bounds;
+	}
+	nativeMacCaptureEvents.emit("helper-event", event);
+}
+
 function inspectNativeMacCaptureOutput() {
 	for (const line of nativeMacCaptureOutput.split(/\r?\n/)) {
 		const event = tryParseNativeHelperEvent(line.trim());
 		if (event) {
-			nativeMacCaptureEvents.emit("helper-event", event);
+			dispatchNativeMacHelperEvent(event);
 		}
 	}
 }
@@ -1059,7 +1077,7 @@ function attachNativeMacCaptureOutputDrain(proc: ChildProcessWithoutNullStreams)
 		for (const line of lines) {
 			const event = tryParseNativeHelperEvent(line.trim());
 			if (event) {
-				nativeMacCaptureEvents.emit("helper-event", event);
+				dispatchNativeMacHelperEvent(event);
 			}
 		}
 	};
@@ -1817,6 +1835,7 @@ export function registerIpcHandlers(
 			nativeMacPauseStartedAtMs = null;
 			nativeMacPauseRanges = [];
 			nativeMacIsPaused = false;
+			activeMacCaptureBounds = null;
 
 			const cursorStartTimeMs = Date.now();
 			if (cursorCaptureMode === "editable-overlay") {
@@ -2132,6 +2151,7 @@ export function registerIpcHandlers(
 			nativeMacPauseStartedAtMs = null;
 			nativeMacPauseRanges = [];
 			nativeMacIsPaused = false;
+			activeMacCaptureBounds = null;
 			const source = selectedSource || { name: "Screen" };
 			if (onRecordingStateChange) {
 				onRecordingStateChange(false, source.name);

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

@@ -124,6 +124,9 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 		let filter: SCContentFilter
 		let width: Int
 		let height: Int
+		// Global frame (points, top-left origin) of the captured region. Used by the
+		// renderer to normalize cursor positions into the captured window's space.
+		let captureFrame: CGRect
 	}
 
 	private let request: RecordingRequest
@@ -143,6 +146,7 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 	private var nativeMicrophoneEnabled = false
 	private var outputWidth = 1920
 	private var outputHeight = 1080
+	private var captureFrame = CGRect.zero
 	private let microphoneOutputTypeRawValue = 2
 	private let hostClock = CMClockGetHostTimeClock()
 
@@ -160,6 +164,7 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 		let target = try makeCaptureTarget(from: content)
 		outputWidth = target.width
 		outputHeight = target.height
+		captureFrame = target.captureFrame
 		let configuration = makeStreamConfiguration()
 		let stream = SCStream(filter: target.filter, configuration: configuration, delegate: self)
 
@@ -178,7 +183,10 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 		try setupWriter()
 
 		self.stream = stream
-		emit(["event": "ready", "schemaVersion": 1])
+		emit([
+			"event": "ready",
+			"schemaVersion": 1,
+		])
 		try await stream.startCapture()
 	}
 
@@ -305,6 +313,7 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 					"timestampMs": Int(Date().timeIntervalSince1970 * 1000),
 					"width": outputWidth,
 					"height": outputHeight,
+					"captureBounds": captureBoundsPayload(),
 				])
 			}
 		}
@@ -337,6 +346,15 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 		}
 	}
 
+	private func captureBoundsPayload() -> [String: Double] {
+		return [
+			"x": captureFrame.origin.x,
+			"y": captureFrame.origin.y,
+			"width": captureFrame.size.width,
+			"height": captureFrame.size.height,
+		]
+	}
+
 	private func makeCaptureTarget(from content: SCShareableContent) throws -> CaptureTarget {
 		switch request.source.type {
 		case "display":
@@ -351,7 +369,8 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 			return CaptureTarget(
 				filter: SCContentFilter(display: display, excludingWindows: []),
 				width: clampCaptureDimension(width, fallback: request.video.width),
-				height: clampCaptureDimension(height, fallback: request.video.height)
+				height: clampCaptureDimension(height, fallback: request.video.height),
+				captureFrame: display.frame
 			)
 		case "window":
 			guard let windowId = request.source.windowId else {
@@ -369,7 +388,8 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 			return CaptureTarget(
 				filter: SCContentFilter(desktopIndependentWindow: window),
 				width: clampCaptureDimension(width, fallback: request.video.width),
-				height: clampCaptureDimension(height, fallback: request.video.height)
+				height: clampCaptureDimension(height, fallback: request.video.height),
+				captureFrame: window.frame
 			)
 		default:
 			throw HelperError.invalidSourceType(request.source.type)

src/lib/nativeMacRecording.ts

@@ -56,6 +56,7 @@ export type NativeMacHelperReadyEvent = {
 export type NativeMacHelperRecordingStartedEvent = {
 	event: "recording-started";
 	timestampMs: number;
+	captureBounds?: Rectangle;
 };
 
 export type NativeMacHelperRecordingStoppedEvent = {