fix: prevent /copy crash on Windows by skipping /dev/tty (#15657)

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

packages/cli/src/ui/utils/commandUtils.test.ts

@@ -98,6 +98,9 @@ describe('commandUtils', () => {
 
   beforeEach(async () => {
     vi.clearAllMocks();
+    // Reset platform to default for test isolation
+    mockProcess.platform = 'darwin';
+
     // Dynamically import and set up spawn mock
     const { spawn } = await import('node:child_process');
     mockSpawn = spawn as Mock;
@@ -354,6 +357,35 @@ describe('commandUtils', () => {
       expect(tty.write).not.toHaveBeenCalled();
       expect(tty.end).not.toHaveBeenCalled();
     });
+
+    it('skips /dev/tty on Windows and uses stderr fallback for OSC-52', async () => {
+      mockProcess.platform = 'win32';
+      const stderrStream = makeWritable({ isTTY: true });
+      Object.defineProperty(process, 'stderr', {
+        value: stderrStream,
+        configurable: true,
+      });
+
+      // Set SSH environment to trigger OSC-52 path
+      process.env['SSH_CONNECTION'] = '1';
+
+      await copyToClipboard('windows-ssh-test');
+
+      expect(mockFs.createWriteStream).not.toHaveBeenCalled();
+      expect(stderrStream.write).toHaveBeenCalled();
+      expect(mockClipboardyWrite).not.toHaveBeenCalled();
+    });
+
+    it('uses clipboardy on native Windows without SSH/WSL', async () => {
+      mockProcess.platform = 'win32';
+      mockClipboardyWrite.mockResolvedValue(undefined);
+
+      await copyToClipboard('windows-native-test');
+
+      // Fallback to clipboardy and not /dev/tty
+      expect(mockClipboardyWrite).toHaveBeenCalledWith('windows-native-test');
+      expect(mockFs.createWriteStream).not.toHaveBeenCalled();
+    });
   });
 
   describe('getUrlOpenCommand', () => {

packages/cli/src/ui/utils/commandUtils.ts

@@ -66,13 +66,19 @@ const SCREEN_DCS_CHUNK_SIZE = 240;
 type TtyTarget = { stream: Writable; closeAfter: boolean } | null;
 
 const pickTty = (): TtyTarget => {
-  // Prefer the controlling TTY to avoid interleaving escape sequences with piped stdout.
-  try {
-    const devTty = fs.createWriteStream('/dev/tty');
-    return { stream: devTty, closeAfter: true };
-  } catch {
-    // fall through
+  // /dev/tty is only available on Unix-like systems (Linux, macOS, BSD, etc.)
+  if (process.platform !== 'win32') {
+    // Prefer the controlling TTY to avoid interleaving escape sequences with piped stdout.
+    try {
+      const devTty = fs.createWriteStream('/dev/tty');
+      // Prevent unhandled 'error' events from crashing the process.
+      devTty.on('error', () => {});
+      return { stream: devTty, closeAfter: true };
+    } catch {
+      // fall through - /dev/tty not accessible
+    }
   }
+
   if (process.stderr?.isTTY)
     return { stream: process.stderr, closeAfter: false };
   if (process.stdout?.isTTY)