diff --git a/electron/electron-env.d.ts b/electron/electron-env.d.ts
index a1aa8880..63f1caef 100644
--- a/electron/electron-env.d.ts
+++ b/electron/electron-env.d.ts
@@ -427,7 +427,7 @@ interface Window {
 			},
 		) => Promise<{
 			success: boolean;
-			data?: Uint8Array;
+			tempPath?: string;
 			error?: string;
 			metrics?: RendererFfmpegAudioMuxMetrics;
 		}>;
diff --git a/electron/ipc/export/native-video.test.ts b/electron/ipc/export/native-video.test.ts
index 91f11c01..7bc25eaa 100644
--- a/electron/ipc/export/native-video.test.ts
+++ b/electron/ipc/export/native-video.test.ts
@@ -2,19 +2,52 @@ import { describe, expect, it, vi } from "vitest";
 
 vi.mock("electron", () => ({
 	app: {
-		getAppPath: () => process.cwd(),
-		getPath: () => process.env.TEMP ?? process.cwd(),
+		getAppPath: vi.fn(() => process.cwd()),
+		getPath: vi.fn(() => process.env.TEMP ?? process.cwd()),
 		isPackaged: false,
 	},
 }));
 
 vi.mock("../ffmpeg/binary", () => ({
-	getFfmpegBinaryPath: () => "ffmpeg",
+	getFfmpegBinaryPath: vi.fn(() => "ffmpeg"),
+}));
+
+vi.mock("../state", () => ({
+	cachedNativeVideoEncoder: null,
+	setCachedNativeVideoEncoder: vi.fn(),
+}));
+
+const fsMocks = vi.hoisted(() => ({
+	access: vi.fn(async () => {
+		throw new Error("missing");
+	}),
+	writeFile: vi.fn(async () => undefined),
+	readFile: vi.fn(),
+	stat: vi.fn(async () => ({ size: 5_000_000_000 })),
+	unlink: vi.fn(async () => undefined),
+}));
+
+vi.mock("node:fs/promises", () => ({
+	default: fsMocks,
+	...fsMocks,
+}));
+
+const execFileMock = vi.hoisted(() =>
+	vi.fn((_cmd: string, _args: string[], _opts: unknown, cb: (err: Error | null) => void) => {
+		cb(null);
+		return { stdout: "", stderr: "" } as unknown;
+	}),
+);
+
+vi.mock("node:child_process", () => ({
+	execFile: execFileMock,
+	spawn: vi.fn(),
 }));
 
 import {
 	buildNativeVideoAudioMuxArgs,
 	getNvidiaCudaAudioExportSkipReason,
+	muxExportedVideoAudioBuffer,
 	normalizeNativeStaticLayoutBackground,
 	parseFfmpegDurationSeconds,
 	parseFfmpegFrameRate,
@@ -97,6 +130,26 @@ describe("getNvidiaCudaAudioExportSkipReason", () => {
 	});
 });
 
+describe("muxExportedVideoAudioBuffer", () => {
+	it("returns the muxed output path without reading the muxed file into memory", async () => {
+		const videoData = new ArrayBuffer(64);
+		const result = await muxExportedVideoAudioBuffer(videoData, { audioMode: "none" });
+
+		expect(typeof result.outputPath).toBe("string");
+		expect(result.outputPath.length).toBeGreaterThan(0);
+		// The >2 GiB fix relies on stat-only metric collection; readFile must stay unused.
+		expect(fsMocks.readFile).not.toHaveBeenCalled();
+		expect(result.metrics.muxedVideoBytes).toBe(5_000_000_000);
+	});
+
+	it("preserves the input temp path when audioMode='none' (no re-mux)", async () => {
+		const videoData = new ArrayBuffer(32);
+		const result = await muxExportedVideoAudioBuffer(videoData, { audioMode: "none" });
+
+		expect(result.outputPath).toMatch(/recordly-export-video-/);
+	});
+});
+
 describe("buildNativeVideoAudioMuxArgs", () => {
 	it("stream-copies source audio and preserves the requested video duration", () => {
 		const args = buildNativeVideoAudioMuxArgs("video.mp4", "source.mp4", "out.mp4", {
@@ -172,7 +225,7 @@ describe("parseWindowsGpuExportSummary", () => {
 });
 
 describe("parseNvidiaCudaExportSummary", () => {
-	it("parses the pretty JSON summary emitted by the CUDA lab wrapper", () => {
+	it("parses the pretty JSON summary emitted by the CUDA wrapper", () => {
 		const summary = parseNvidiaCudaExportSummary(
 			[
 				"preflight",
@@ -198,7 +251,7 @@ describe("parseNvidiaCudaExportSummary", () => {
 	});
 
 	it("returns null when the wrapper output has no JSON object", () => {
-		expect(parseNvidiaCudaExportSummary("native probe failed before summary")).toBeNull();
+		expect(parseNvidiaCudaExportSummary("native helper failed before summary")).toBeNull();
 	});
 });
 
diff --git a/electron/ipc/export/native-video.ts b/electron/ipc/export/native-video.ts
index 97964ada..eb79fafc 100644
--- a/electron/ipc/export/native-video.ts
+++ b/electron/ipc/export/native-video.ts
@@ -2843,6 +2843,8 @@ export async function muxExportedVideoAudioBuffer(
 		`recordly-export-video-${Date.now()}-${Math.random().toString(36).slice(2, 8)}.mp4`,
 	);
 	const metrics: NativeVideoAudioMuxMetrics = {};
+	let succeeded = false;
+	let outputPath = tempVideoPath;
 
 	try {
 		const tempVideoWriteStartedAt = getNowMs();
@@ -2851,23 +2853,35 @@ export async function muxExportedVideoAudioBuffer(
 		metrics.tempVideoBytes = videoData.byteLength;
 		const finalized = await muxNativeVideoExportAudio(tempVideoPath, options);
 		Object.assign(metrics, finalized.metrics);
-		const muxedVideoReadStartedAt = getNowMs();
-		const muxedData = await fs.readFile(finalized.outputPath);
-		metrics.muxedVideoReadMs = getNowMs() - muxedVideoReadStartedAt;
-		metrics.muxedVideoBytes = muxedData.byteLength;
+		outputPath = finalized.outputPath;
+		// Record byte size via stat instead of reading the whole file into a
+		// Buffer — fs.readFile throws ERR_FS_FILE_TOO_LARGE on >2 GiB outputs.
+		try {
+			const stat = await fs.stat(outputPath);
+			metrics.muxedVideoBytes = stat.size;
+		} catch {
+			// Stat failures are non-fatal; size is purely metric data.
+		}
+		succeeded = true;
 		return {
-			data: new Uint8Array(muxedData),
+			outputPath,
 			metrics,
 		};
 	} finally {
-		await Promise.allSettled([
-			removeTemporaryExportFile(tempVideoPath),
-			removeTemporaryExportFile(
-				path.join(
-					path.dirname(tempVideoPath),
-					`${path.basename(tempVideoPath, path.extname(tempVideoPath))}-final.mp4`,
-				),
-			),
-		]);
+		// Always remove the unmuxed intermediate when the muxer wrote a separate
+		// file. Only remove the muxed output on failure — on success the caller
+		// owns it and is responsible for moving/deleting it.
+		const cleanupTargets: string[] = [];
+		if (outputPath !== tempVideoPath) {
+			cleanupTargets.push(tempVideoPath);
+		}
+		if (!succeeded) {
+			cleanupTargets.push(outputPath);
+		}
+		if (cleanupTargets.length > 0) {
+			await Promise.allSettled(
+				cleanupTargets.map((target) => removeTemporaryExportFile(target)),
+			);
+		}
 	}
 }
diff --git a/electron/ipc/register/export.ts b/electron/ipc/register/export.ts
index 05af28a9..8a73e17b 100644
--- a/electron/ipc/register/export.ts
+++ b/electron/ipc/register/export.ts
@@ -488,9 +488,14 @@ export function registerExportHandlers() {
 		async (_, videoData: ArrayBuffer, options?: NativeVideoExportFinishOptions) => {
 			try {
 				const result = await muxExportedVideoAudioBuffer(videoData, options ?? {});
+				// Register the muxed output so finalize-exported-video / discard-
+				// exported-temp accept it. Returning a temp path (instead of the
+				// muxed bytes) keeps us off Node's >2 GiB fs.readFile cap and
+				// avoids a redundant copy through the renderer.
+				registerOwnedExportPath(result.outputPath);
 				return {
 					success: true,
-					data: result.data,
+					tempPath: result.outputPath,
 					metrics: result.metrics,
 				};
 			} catch (error) {
diff --git a/electron/preload.ts b/electron/preload.ts
index 69f2ef8b..f298ae29 100644
--- a/electron/preload.ts
+++ b/electron/preload.ts
@@ -368,7 +368,7 @@ contextBridge.exposeInMainWorld("electronAPI", {
 	) => {
 		return ipcRenderer.invoke("mux-exported-video-audio", videoData, options) as Promise<{
 			success: boolean;
-			data?: Uint8Array;
+			tempPath?: string;
 			error?: string;
 			metrics?: NativeVideoAudioMuxMetrics;
 		}>;
diff --git a/src/lib/exporter/modernVideoExporter.ts b/src/lib/exporter/modernVideoExporter.ts
index bb374f12..ed3df285 100644
--- a/src/lib/exporter/modernVideoExporter.ts
+++ b/src/lib/exporter/modernVideoExporter.ts
@@ -2153,17 +2153,18 @@ export class ModernVideoExporter {
 			this.finalizationStageMs.ffmpegAudioMuxBreakdown = result.metrics;
 		}
 
-		if (!result.success || !result.data) {
+		if (!result.success || !result.tempPath) {
 			return {
 				success: false,
 				error: result.error || "Failed to mux exported audio with FFmpeg",
 			};
 		}
 
-		const videoBytes = result.data.slice();
+		// Returning a temp path (instead of buffering the muxed bytes back into
+		// the renderer) is what keeps >2 GiB exports off Node's fs.readFile cap.
 		return {
 			success: true,
-			blob: new Blob([videoBytes.buffer], { type: "video/mp4" }),
+			tempFilePath: result.tempPath,
 		};
 	}
 
diff --git a/src/lib/exporter/videoExporter.ts b/src/lib/exporter/videoExporter.ts
index bcc887ca..f8581910 100644
--- a/src/lib/exporter/videoExporter.ts
+++ b/src/lib/exporter/videoExporter.ts
@@ -981,7 +981,7 @@ export class VideoExporter {
 			this.finalizationStageMs.ffmpegAudioMuxBreakdown = result.metrics;
 		}
 
-		if (!result.success || !result.data) {
+		if (!result.success || !result.tempPath) {
 			return {
 				success: false,
 				error: result.error || "Failed to mux exported audio with FFmpeg",
@@ -989,11 +989,11 @@ export class VideoExporter {
 			};
 		}
 
-		const blobData = new Uint8Array(result.data.byteLength);
-		blobData.set(result.data);
+		// Returning a temp path (instead of buffering the muxed bytes back into
+		// the renderer) is what keeps >2 GiB exports off Node's fs.readFile cap.
 		return {
 			success: true,
-			blob: new Blob([blobData.buffer], { type: "video/mp4" }),
+			tempFilePath: result.tempPath,
 			metrics: this.buildExportMetrics(),
 		};
 	}