web Plugin

web is a real web-capability plugin. It no longer only injects methodology or returns installation prompts. It composes providers explicitly supplied by the host and does not bind the SDK to a search vendor, cloud browser, or Computer Use model.

Playwright/CDP

import {
  PlaywrightBrowserProvider,
  WebPlugin,
} from "@downcity/plugins/web";

const web = new WebPlugin({
  browser: new PlaywrightBrowserProvider({
    cdp_url: "http://127.0.0.1:9222",
  }),
});

PlaywrightBrowserProvider connects to an already-running Chrome/Chromium CDP endpoint. It does not download browsers or execute installation commands. Browserbase, Browserless, Kitesurf, and other CDP-compatible backends can implement the same BrowserProvider protocol.

Actions

Provider composition

const web = new WebPlugin({
  search: (input) => search_service.search(input),
  open: (input) => reader_service.open(input),
  browser: browser_provider,
});

Semantic capabilities are injected through an adapter and are not tied to one model vendor:

import { SemanticBrowserProviderAdapter } from "@downcity/plugins/web";

const browser = new SemanticBrowserProviderAdapter({
  name: "stagehand",
  browser: playwright_browser,
  semantic_act: (input) => stagehand_service.act(input),
  semantic_extract: (input) => stagehand_service.extract(input),
});

Computer Use can use ComputerUseBrowserProviderAdapter. It captures an observation with a screenshot before handing the goal to an OpenAI, Anthropic, Gemini, or custom model loop. The model never receives Playwright objects.

Use search or HTTP reading first. Create a browser for dynamic rendering, logged-in state, or interaction. Stagehand can be added inside a provider for semantic actions, while Computer Use should remain a visual fallback for pages that cannot be handled reliably through the DOM.

Lifecycle and safety

• WebPlugin requires at least one configured provider.
• The provider owns browser sessions and is disposed when the Agent or Plugin is disposed.
• browser_act exposes deterministic browser actions. Host approval is required for consequential actions such as submit, send, purchase, upload, or delete.
• Playwright Browser, Page, and Buffer objects never cross the Plugin action boundary; results are JSON-serializable.
• Skill installation, discovery, and SKILL.md loading remain responsibilities of SkillPlugin.

Related docs

• Built-in Plugin overview
• Plugin Actions
• Plugin System