Bug Browser CDP Mode Broken on Windows with Chrome 145

Google Antigravity
1

# [Bug] Browser CDP mode broken on Windows with Chrome 145 — language_server Playwright incompatibility

## Environment

- **OS**: Windows 10 (x64)

- **Antigravity Version**: Latest (Feb 2026)

- **Chrome Version**: 145.0.7632.110

- **language_server**: `language_server_windows_x64.exe`

## Description

The browser subagent (CDP mode) completely fails on Windows. Every `open_browser_url` call fails with:

```

failed to connect to browser via CDP even though the CDP port is responsive:

http://127.0.0.1:9222: playwright: Unexpected status 400 when connecting to

http://127.0.0.1:9222/json/version/.

This does not look like a DevTools server, try connecting via ws://.

```

**The same setup works fine on macOS.**

## Root Cause Analysis

After extensive debugging, I confirmed the issue is **inside the `language_server` binary’s bundled Playwright**, not Chrome or any external configuration.

### Evidence: External Playwright works perfectly

```bash

$ npm install playwright-core

$ node -e "

const { chromium } = require(‘playwright-core’);

(async () => {

const browser = await chromium.connectOverCDP(‘http://127.0.0.1:9222’);

console.log(‘Connected:’, browser.version());

const page = await browser.contexts()[0].newPage();

await page.goto(‘https://www.example.com’);

console.log(‘Title:’, await page.title());

await browser.close();

})();"

```

**Output:**

```

Connected: 145.0.7632.110

Title: Example Domain

```

### Evidence: All other HTTP clients work

| Client | Request to `/json/version/` | Status |

|--------|---------------------------|--------|

| `curl.exe` | :white_check_mark: 200 OK | Works |

| PowerShell `Invoke-WebRequest` | :white_check_mark: 200 OK | Works |

| Node.js `http.request` | :white_check_mark: 200 OK | Works |

| External `playwright-core` (latest) | :white_check_mark: Connected + page loaded | Works |

| **Antigravity `language_server` internal Playwright** | :cross_mark: **HTTP 400** | **Broken** |

### Hypotheses Ruled Out

- :cross_mark: Chrome version incompatibility — external Playwright connects fine

- :cross_mark: Missing `HOME` environment variable — set it, no effect

- :cross_mark: Corrupted browser profile — deleted and recreated, no effect

- :cross_mark: HTTP proxy interference — removed all proxy settings, no effect; system proxy is disabled

- :cross_mark: Port conflict — port 9222 is exclusively used by Antigravity’s managed Chrome

- :cross_mark: Multiple Chrome instances conflicting — external Playwright works even with multiple Chrome instances running

## Conclusion

The `language_server_windows_x64.exe` bundles an older or modified version of Playwright whose `connectOverCDP` implementation is incompatible with Chrome 145 on Windows. The latest Playwright-core (npm) works perfectly with the exact same Chrome instance on the exact same machine.

## Expected Behavior

Browser subagent should successfully connect to Chrome via CDP on Windows, just as it does on macOS.

## Steps to Reproduce

1. Install Antigravity on Windows with Chrome 145+

2. Attempt any browser subagent task (e.g., navigate to a URL)

3. Observe the `Unexpected status 400` error

## Suggested Fix

Update the Playwright version bundled inside `language_server_windows_x64.exe` to match the latest `playwright-core` which handles Chrome 145 CDP correctly.