fix(mcp): split header value only on first colon in headerParser

packages/playwright-core/src/mcp/config.ts

@@ -432,7 +432,10 @@ export function headerParser(arg: string | undefined, previous?: Record<string,
   if (!arg)
     return previous || {};
   const result: Record<string, string> = previous || {};
-  const [name, value] = arg.split(':').map(v => v.trim());
+  const colonIndex = arg.indexOf(':');
+
+  const name = colonIndex === -1 ? arg.trim() : arg.substring(0, colonIndex).trim();
+  const value = colonIndex === -1 ? '' : arg.substring(colonIndex + 1).trim();
   result[name] = value;
   return result;
 }

tests/mcp/cdp.spec.ts

@@ -110,3 +110,29 @@ test('cdp server with headers', async ({ startClient, server }) => {
   });
   expect(authHeader).toBe('Bearer 1234567890');
 });
+
+test('cdp server with empty and complex headers', async ({ startClient, server }) => {
+  let customHeader = '';
+  let emptyHeader = '';
+  server.setRoute('/json/version/', (req, res) => {
+    customHeader = req.headers['x-forwarded-proto'] as string;
+    emptyHeader = req.headers['x-empty'] as string;
+    res.end();
+  });
+
+  const { client } = await startClient({
+    args: [
+      `--cdp-endpoint=${server.PREFIX}`,
+      '--cdp-header', 'X-Forwarded-Proto: value:with:colons',
+      '--cdp-header', 'X-Empty'
+    ]
+  });
+  expect(await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  })).toHaveResponse({
+    isError: true,
+  });
+  expect(customHeader).toBe('value:with:colons');
+  expect(emptyHeader).toBe('');
+});