Bug Summary

agent-browser --cdp 9222 open <url> kills the external Chrome process instead of gracefully disconnecting when the CDP connection validation fails.

Environment

• agent-browser: 0.14.0
• Chrome Canary: 147.0.7701.0
• macOS, ARM64
• playwright-core (bundled)

Reproduction

1. Start Chrome with remote debugging:

   /Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --remote-debugging-port=9222

2. Verify CDP is active:

   curl -s http://localhost:9222/json/version  # returns valid JSON

3. Run:

   agent-browser --cdp 9222 open https://example.com

4. Result: Chrome Canary process is killed. curl -s http://localhost:9222/json/version returns empty.

Contrast: agent-browser --cdp 9222 tab new https://example.com works correctly without killing Chrome.

Root Cause

Two locations in dist/browser.js call browser.close() on a Playwright Browser object obtained via chromium.connectOverCDP(). Playwright's connectOverCDP() does not set _shouldCloseConnectionOnClose = true (unlike connect()), so .close() sends the CDP Browser.close command which terminates the browser process.

Location 1: connectViaCDP error handler (line ~1202-1205)

catch (error) {
    // Clean up browser connection if validation or setup failed
    await browser.close().catch(() => { });  // <-- kills Chrome!
    throw error;
}

If anything throws during page validation (e.g., no pages with non-empty URLs, setupPageTracking failure), this catch block runs browser.close() which sends Browser.close via CDP → Chrome dies.

Location 2: BrowserManager.close() (line ~1990-1995)

else if (this.cdpEndpoint !== null) {
    // CDP: only disconnect, don't close external app's pages
    if (this.browser) {
        await this.browser.close().catch(() => { });  // <-- also kills Chrome!
    }
}

The comment explicitly says "only disconnect, don't close external app's pages" but .close() does the opposite for CDP connections.

Playwright behavior reference

Suggested Fix

Replace browser.close() with a disconnect-only call at both locations. Options:

1. Preferred: Use browser.disconnect() if available, or access the underlying connection:

   // In connectViaCDP catch block:
   await browser._connection?.close();
   
   // In BrowserManager.close() CDP branch:
   await browser._connection?.close();

2. Alternative: Set the flag after connecting:

   const browser = await chromium.connectOverCDP(cdpUrl, { timeout: options?.timeout });
   browser._shouldCloseConnectionOnClose = true;  // Ensure close() only disconnects

3. Simplest: Just don't call close in the error handler — let the WebSocket connection be garbage-collected:

   catch (error) {
       // Don't call browser.close() — it kills external Chrome via CDP
       throw error;
   }

Why tab new works

tab new <url> runs after connectViaCDP has already succeeded (the try block completed). It creates a new page via context.newPage() + page.goto() — no risk of hitting the catch block with browser.close().