fix(coding-agent): harden clipboard copy

closes #3639

packages/coding-agent/test/clipboard.test.ts

@@ -0,0 +1,145 @@
+import { execSync, spawn } from "child_process";
+import { platform } from "os";
+import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
+import { copyToClipboard } from "../src/utils/clipboard.js";
+
+const mocks = vi.hoisted(() => {
+	return {
+		clipboard: {
+			setText: vi.fn<(text: string) => Promise<void>>(),
+		},
+		execSync: vi.fn(),
+		spawn: vi.fn(),
+		platform: vi.fn<() => NodeJS.Platform>(),
+		isWaylandSession: vi.fn<() => boolean>(),
+	};
+});
+
+vi.mock("../src/utils/clipboard-native.js", () => {
+	return {
+		clipboard: mocks.clipboard,
+	};
+});
+
+vi.mock("child_process", () => {
+	return {
+		execSync: mocks.execSync,
+		spawn: mocks.spawn,
+	};
+});
+
+vi.mock("os", () => {
+	return {
+		platform: mocks.platform,
+	};
+});
+
+vi.mock("../src/utils/clipboard-image.js", () => {
+	return {
+		isWaylandSession: mocks.isWaylandSession,
+	};
+});
+
+const mockedExecSync = vi.mocked(execSync);
+const mockedSpawn = vi.mocked(spawn);
+const mockedPlatform = vi.mocked(platform);
+
+let originalWrite: typeof process.stdout.write;
+let stdoutWrites: string[];
+let nativeResolved = false;
+
+function osc52Writes(): string[] {
+	return stdoutWrites.filter((write) => write.startsWith("\x1b]52;c;"));
+}
+
+beforeEach(() => {
+	vi.unstubAllEnvs();
+	stdoutWrites = [];
+	nativeResolved = false;
+	mocks.clipboard.setText.mockReset();
+	mocks.execSync.mockReset();
+	mocks.spawn.mockReset();
+	mocks.platform.mockReset();
+	mocks.isWaylandSession.mockReset();
+	mockedPlatform.mockReturnValue("darwin");
+	mocks.isWaylandSession.mockReturnValue(false);
+	mocks.clipboard.setText.mockImplementation(async () => {
+		await new Promise((resolve) => setTimeout(resolve, 1));
+		nativeResolved = true;
+	});
+	originalWrite = process.stdout.write.bind(process.stdout);
+	process.stdout.write = ((...args: Parameters<typeof process.stdout.write>) => {
+		const [chunk] = args;
+		if (typeof chunk === "string" && chunk.startsWith("\x1b]52;c;")) {
+			stdoutWrites.push(chunk);
+			return true;
+		}
+		return originalWrite(...args);
+	}) as typeof process.stdout.write;
+});
+
+afterEach(() => {
+	process.stdout.write = originalWrite;
+	vi.unstubAllEnvs();
+});
+
+describe("copyToClipboard", () => {
+	test("local native success skips OSC 52 and shell fallbacks", async () => {
+		await copyToClipboard("hello");
+
+		expect(mocks.clipboard.setText).toHaveBeenCalledWith("hello");
+		expect(osc52Writes()).toHaveLength(0);
+		expect(mockedExecSync).not.toHaveBeenCalled();
+		expect(mockedSpawn).not.toHaveBeenCalled();
+	});
+
+	test("remote native success emits OSC 52 after native write", async () => {
+		vi.stubEnv("SSH_CONNECTION", "client server");
+		mocks.clipboard.setText.mockImplementation(async () => {
+			await new Promise((resolve) => setTimeout(resolve, 1));
+			expect(osc52Writes()).toHaveLength(0);
+			nativeResolved = true;
+		});
+
+		await copyToClipboard("hello");
+
+		expect(nativeResolved).toBe(true);
+		expect(osc52Writes()).toHaveLength(1);
+		expect(mockedExecSync).not.toHaveBeenCalled();
+	});
+
+	test("local shell fallback success skips OSC 52", async () => {
+		mocks.clipboard.setText.mockRejectedValue(new Error("native failed"));
+		mockedExecSync.mockReturnValue(Buffer.alloc(0));
+
+		await copyToClipboard("hello");
+
+		expect(mockedExecSync).toHaveBeenCalledWith("pbcopy", {
+			input: "hello",
+			stdio: ["pipe", "ignore", "ignore"],
+			timeout: 5000,
+		});
+		expect(osc52Writes()).toHaveLength(0);
+	});
+
+	test("uses OSC 52 fallback when native and shell tools fail", async () => {
+		mocks.clipboard.setText.mockRejectedValue(new Error("native failed"));
+		mockedExecSync.mockImplementation(() => {
+			throw new Error("pbcopy failed");
+		});
+
+		await copyToClipboard("hello");
+
+		expect(osc52Writes()).toHaveLength(1);
+	});
+
+	test("does not emit oversized OSC 52 payloads", async () => {
+		mocks.clipboard.setText.mockRejectedValue(new Error("native failed"));
+		mockedExecSync.mockImplementation(() => {
+			throw new Error("pbcopy failed");
+		});
+
+		await expect(copyToClipboard("x".repeat(80_000))).rejects.toThrow("Failed to copy to clipboard");
+		expect(osc52Writes()).toHaveLength(0);
+	});
+});