computer: Add a ws:browser host module

[mattzcarey]

Adds an experimental ws:browser host module, createBrowserModule() from @cloudflare/computer/modules/browser. Code that exec runs can drive a persistent Chrome browser over the Chrome DevTools Protocol with send, attachToTarget, spec, getDebugLog and clearDebugLog.

import { Browser, browserRun } from "agents/browser";
import { createBrowserModule } from "@cloudflare/computer/modules/browser";

modules: { "ws:browser": createBrowserModule({ browser: this.browser }) }

import { send } from "ws:browser";
export default () => send({ method: "Page.navigate", params: { url }, sessionId: "active" });

The agents SDK's browser tools run on @cloudflare/codemode, which is being deprecated, and running code is moving to exec on a Workspace. The browser itself (sessions, Browser Run, Live View) stays in agents. So this module takes anything with the BrowserSource shape: a name and a connect({ scope }) that returns a CDP connection plus the scope's active tab. Browser from agents/browser has that shape, so neither package imports the other. A scratch type check confirmed Browser is assignable to BrowserSource.

Behavior follows the agents browser tool:

• sessionId: "active" is the scope's tab, remembered between runs;
• attachToTarget returns handles that work across runs;
• Browser.close is refused;
• the common CDP mistakes get hints.

Each run gets its own connection, keyed by executionId. A deferred function saves the active tab, closes the connection, and writes restarts and tabs the page opened to standard error. The module's description covers the calls and those rules for the model.

npm test in packages/computer and npm run check ran. Unit tests use an in-memory browser that keeps tabs and active tabs across connections. A workerd test imports ws:browser from exec code and sees a restart on standard error. docs/17_isolate_javascript.md and the package README's status table cover the module.

Stacked on #247, which adds executionId, log and defer.

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🦋 Changeset detected

Latest commit: f11d1ad

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@cloudflare/computer	Minor
@cloudflare/dofs	Minor
@cloudflare/computer-rpc	Minor
@cloudflare/computerd	Minor

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commit: f11d1ad