VulpineOS Method Passthrough

foxbridge primarily translates standard CDP methods into Firefox Juggler. It also forwards a small set of VulpineOS-specific Page.* methods directly so CDP clients can access them without speaking Juggler.

Currently forwarded methods

foxbridge currently forwards these methods directly to the Juggler backend:

Page.getOptimizedDOM
Page.resolveRef
Page.focusByRef
Page.setActionLock
Page.getShadowDOM

These are not Chrome-native CDP methods. They only work when the target browser is a VulpineOS/Camoufox build that implements the matching Juggler methods.

How to call them

Use a page-scoped CDP session, not the browser-level connection.

Puppeteer


const browser = await puppeteer.connect({
  browserWSEndpoint: 'ws://127.0.0.1:9222/devtools/browser/foxbridge',
});
 
const page = await browser.newPage();
const client = await page.target().createCDPSession();
 
const dom = await client.send('Page.getOptimizedDOM', {
  maxDepth: 10,
  maxNodes: 200,
});
 
await client.send('Page.setActionLock', { enabled: true });
await client.send('Page.focusByRef', { ref: '@3' });

chrome-remote-interface


const CDP = require('chrome-remote-interface');
 
const client = await CDP();
const { Target } = client;
 
const { targetId } = await Target.createTarget({ url: 'about:blank' });
const { sessionId } = await Target.attachToTarget({ targetId, flatten: true });
 
await client.send('Page.getOptimizedDOM', {
  maxNodes: 150,
}, sessionId);

Why these methods exist

These methods expose VulpineOS browser-side features that are useful to agents but do not exist in standard CDP:

Page.getOptimizedDOM: token-reduced semantic DOM export
Page.resolveRef: map a @N reference back to a concrete target
Page.focusByRef: focus an element from a semantic reference
Page.setActionLock: freeze page execution while the agent reasons
Page.getShadowDOM: inspect shadow-root content through the browser

This keeps foxbridge useful for agent tooling while staying explicit about what is VulpineOS-specific behavior.

Limitations

Not every VulpineOS or private Juggler method is exposed through foxbridge.

Methods that are not currently forwarded include:

Page.getAnnotatedScreenshot
Page.secureSetInputValue
Browser.startAudioCapture
Browser.stopAudioCapture
Browser.getAudioChunk

For those features:

use VulpineOS MCP tools when available
or use the direct Juggler path inside VulpineOS
or extend foxbridge explicitly rather than assuming arbitrary Juggler methods will pass through

If a method is not implemented, foxbridge returns a standard CDP method not found error.

Compatibility note

These passthrough methods are a foxbridge convenience for VulpineOS users. They are not part of Chrome CDP and should be treated as VulpineOS-specific extensions by client code.