feat(ext): hub protocol

packages/extension/src/entrypoints/hub/App.tsx

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+import { Plug, PlugZap, Square, Unplug } from 'lucide-react'
+import { useEffect, useRef } from 'react'
+
+import { useAgent } from '@/agent/useAgent'
+import { ActivityCard, EventCard } from '@/components/cards'
+import { Logo, MotionOverlay, StatusDot } from '@/components/misc'
+import { Button } from '@/components/ui/button'
+
+import { useHubWs } from './hub-ws'
+
+export default function App() {
+	const { status, history, activity, currentTask, config, execute, stop, configure } = useAgent()
+	const { wsState } = useHubWs(execute, stop, configure, config)
+
+	const historyRef = useRef<HTMLDivElement>(null)
+
+	useEffect(() => {
+		if (historyRef.current) {
+			historyRef.current.scrollTop = historyRef.current.scrollHeight
+		}
+	}, [history, activity])
+
+	const isRunning = status === 'running'
+	const WsIcon = wsState === 'connected' ? PlugZap : wsState === 'connecting' ? Plug : Unplug
+	const wsLabel = {
+		connected: 'Connected',
+		connecting: 'Connecting…',
+		disconnected: new URLSearchParams(location.search).get('ws') ? 'Disconnected' : 'Standalone',
+	}[wsState]
+
+	return (
+		<div className="flex h-screen bg-background">
+			<MotionOverlay active={isRunning} />
+
+			{/* Left — Protocol docs */}
+			<aside className="w-80 shrink-0 border-r flex flex-col bg-muted/20">
+				<div className="flex items-center gap-2 px-5 py-4 border-b">
+					<Logo className="size-5" />
+					<span className="text-sm font-semibold tracking-tight">Page Agent Hub</span>
+				</div>
+
+				<div className="flex-1 overflow-y-auto px-5 py-4">
+					<ProtocolDocs />
+				</div>
+
+				<div className="border-t px-5 py-3 text-[11px] text-muted-foreground/60">
+					Connect via <code className="text-[10px]">hub.html?ws=PORT</code>
+				</div>
+			</aside>
+
+			{/* Right — Live session */}
+			<main className="flex-1 flex flex-col min-w-0">
+				{/* Header bar */}
+				<header className="flex items-center justify-between border-b px-5 py-3">
+					<div className="flex items-center gap-2 text-xs text-muted-foreground">
+						<WsIcon className="size-3.5" />
+						<span>{wsLabel}</span>
+					</div>
+					<div className="flex items-center gap-3">
+						<StatusDot status={status} />
+						{isRunning && (
+							<Button variant="destructive" size="sm" onClick={stop} className="h-7 text-xs">
+								<Square className="size-3 mr-1" />
+								Stop
+							</Button>
+						)}
+					</div>
+				</header>
+
+				{/* Task banner */}
+				{currentTask && (
+					<div className="border-b px-5 py-2 bg-muted/30">
+						<div className="text-[10px] text-muted-foreground uppercase tracking-wide">
+							Current Task
+						</div>
+						<div className="text-sm font-medium truncate" title={currentTask}>
+							{currentTask}
+						</div>
+					</div>
+				)}
+
+				{/* Event stream */}
+				<div ref={historyRef} className="flex-1 overflow-y-auto p-5 space-y-2">
+					{!currentTask && history.length === 0 && !isRunning && (
+						<div className="flex flex-col items-center justify-center h-full text-muted-foreground gap-3">
+							<WsIcon className="size-10 opacity-30" />
+							<p className="text-sm">
+								{wsState === 'connected'
+									? 'Waiting for task from external caller…'
+									: 'No active session'}
+							</p>
+						</div>
+					)}
+
+					{history.map((event, index) => (
+						// eslint-disable-next-line react-x/no-array-index-key
+						<EventCard key={index} event={event} />
+					))}
+
+					{activity && <ActivityCard activity={activity} />}
+				</div>
+			</main>
+		</div>
+	)
+}
+
+function ProtocolDocs() {
+	return (
+		<div className="space-y-5 text-xs text-muted-foreground">
+			<section>
+				<h3 className="text-[11px] font-semibold text-foreground/80 uppercase tracking-wider mb-2">
+					Caller → Hub
+				</h3>
+				<pre className="bg-muted/50 rounded-md p-3 font-mono text-[10px] leading-relaxed whitespace-pre-wrap">
+					{`{ type: "execute", task: string, config?: object }
+{ type: "stop" }`}
+				</pre>
+			</section>
+
+			<section>
+				<h3 className="text-[11px] font-semibold text-foreground/80 uppercase tracking-wider mb-2">
+					Hub → Caller
+				</h3>
+				<pre className="bg-muted/50 rounded-md p-3 font-mono text-[10px] leading-relaxed whitespace-pre-wrap">
+					{`{ type: "ready" }
+{ type: "result", success: boolean, data: string }
+{ type: "error", message: string }`}
+				</pre>
+			</section>
+
+			<section>
+				<h3 className="text-[11px] font-semibold text-foreground/80 uppercase tracking-wider mb-2">
+					Flow
+				</h3>
+				<ol className="list-decimal list-inside space-y-1 text-[11px] leading-relaxed">
+					<li>Hub opens WS to caller's server</li>
+					<li>
+						Sends <code className="text-[10px]">ready</code>
+					</li>
+					<li>
+						Caller sends <code className="text-[10px]">execute</code> with task
+					</li>
+					<li>Hub runs agent, streams events</li>
+					<li>
+						Hub sends <code className="text-[10px]">result</code> or{' '}
+						<code className="text-[10px]">error</code>
+					</li>
+				</ol>
+			</section>
+		</div>
+	)
+}

packages/extension/src/entrypoints/hub/hub-ws.ts

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+/**
+ * Hub WebSocket Protocol
+ *
+ * Hub connects as WS client to `ws://localhost:{port}`.
+ * All messages are JSON. One task at a time.
+ *
+ * Inbound (Caller → Hub):
+ *   { type: "execute", task: string, config?: object }
+ *   { type: "stop" }
+ *
+ * Outbound (Hub → Caller):
+ *   { type: "ready" }
+ *   { type: "result", success: boolean, data: string }
+ *   { type: "error", message: string }
+ */
+import type { ExecutionResult } from '@page-agent/core'
+import { useEffect, useRef, useState } from 'react'
+
+import type { ExtConfig } from '@/agent/useAgent'
+
+// --- Protocol types ---
+
+interface ExecuteMessage {
+	type: 'execute'
+	task: string
+	config?: Record<string, unknown>
+}
+
+interface StopMessage {
+	type: 'stop'
+}
+
+type InboundMessage = ExecuteMessage | StopMessage
+
+interface ReadyMessage {
+	type: 'ready'
+}
+
+interface ResultMessage {
+	type: 'result'
+	success: boolean
+	data: string
+}
+
+interface ErrorMessage {
+	type: 'error'
+	message: string
+}
+
+type OutboundMessage = ReadyMessage | ResultMessage | ErrorMessage
+
+export type HubWsState = 'connecting' | 'connected' | 'disconnected'
+
+// --- HubWs class ---
+
+export interface HubWsHandlers {
+	onExecute: (
+		task: string,
+		config?: Record<string, unknown>
+	) => Promise<{ success: boolean; data: string }>
+	onStop: () => void
+}
+
+/**
+ * Framework-agnostic WebSocket client for Hub.
+ * Connects to an external WS server, receives tasks, dispatches to handlers,
+ * and sends results back. No React, no DOM.
+ */
+export class HubWs {
+	#ws: WebSocket | null = null
+	#state: HubWsState = 'disconnected'
+	#busy = false
+	#handlers: HubWsHandlers
+	#port: number
+	#onStateChange: (state: HubWsState) => void
+
+	constructor(port: number, handlers: HubWsHandlers, onStateChange: (state: HubWsState) => void) {
+		this.#port = port
+		this.#handlers = handlers
+		this.#onStateChange = onStateChange
+	}
+
+	get state() {
+		return this.#state
+	}
+
+	get busy() {
+		return this.#busy
+	}
+
+	connect() {
+		if (this.#ws) return
+		this.#setState('connecting')
+
+		const ws = new WebSocket(`ws://localhost:${this.#port}`)
+		this.#ws = ws
+
+		ws.addEventListener('open', () => {
+			this.#setState('connected')
+			this.#send({ type: 'ready' })
+		})
+
+		ws.addEventListener('close', () => {
+			this.#ws = null
+			this.#busy = false
+			this.#setState('disconnected')
+		})
+
+		ws.addEventListener('message', (event) => {
+			this.#handleMessage(event.data as string)
+		})
+	}
+
+	disconnect() {
+		this.#ws?.close()
+		this.#ws = null
+		this.#busy = false
+		this.#setState('disconnected')
+	}
+
+	#setState(state: HubWsState) {
+		if (this.#state === state) return
+		this.#state = state
+		this.#onStateChange(state)
+	}
+
+	#send(msg: OutboundMessage) {
+		if (this.#ws?.readyState === WebSocket.OPEN) {
+			this.#ws.send(JSON.stringify(msg))
+		}
+	}
+
+	#handleMessage(raw: string) {
+		let msg: InboundMessage
+		try {
+			msg = JSON.parse(raw)
+		} catch {
+			return
+		}
+
+		switch (msg.type) {
+			case 'execute':
+				this.#handleExecute(msg)
+				break
+			case 'stop':
+				this.#handlers.onStop()
+				break
+		}
+	}
+
+	async #handleExecute(msg: ExecuteMessage) {
+		if (this.#busy) {
+			this.#send({ type: 'error', message: 'Hub is busy with another task' })
+			return
+		}
+
+		this.#busy = true
+		try {
+			const result = await this.#handlers.onExecute(msg.task, msg.config)
+			this.#send({ type: 'result', success: result.success, data: result.data })
+		} catch (err) {
+			this.#send({ type: 'error', message: err instanceof Error ? err.message : String(err) })
+		} finally {
+			this.#busy = false
+		}
+	}
+}
+
+// --- React hook ---
+
+/**
+ * React hook that bridges HubWs to the agent's execute/stop/configure.
+ * Handles the config-before-execute dance internally.
+ */
+export function useHubWs(
+	execute: (task: string) => Promise<ExecutionResult>,
+	stop: () => void,
+	configure: (config: ExtConfig) => Promise<void>,
+	config: ExtConfig | null
+): { wsState: HubWsState } {
+	const wsPort = new URLSearchParams(location.search).get('ws')
+	const [wsState, setWsState] = useState<HubWsState>(() => (wsPort ? 'connecting' : 'disconnected'))
+	const hubWsRef = useRef<HubWs | null>(null)
+
+	const latest = useRef({ execute, stop, configure, config })
+	useEffect(() => {
+		latest.current = { execute, stop, configure, config }
+	})
+
+	useEffect(() => {
+		if (!wsPort) return
+
+		const hubWs = new HubWs(
+			Number(wsPort),
+			{
+				onExecute: async (task, incomingConfig) => {
+					const { execute, configure, config } = latest.current
+					if (incomingConfig) {
+						await configure({ ...config, ...incomingConfig } as ExtConfig)
+					}
+					const result = await execute(task)
+					return { success: result.success, data: result.data }
+				},
+				onStop: () => latest.current.stop(),
+			},
+			setWsState
+		)
+
+		hubWs.connect()
+		hubWsRef.current = hubWs
+
+		return () => {
+			hubWs.disconnect()
+			hubWsRef.current = null
+		}
+	}, [wsPort])
+
+	return { wsState }
+}

packages/extension/src/entrypoints/hub/index.html

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+<!doctype html>
+<html>
+	<head>
+		<meta charset="UTF-8" />
+		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
+		<link rel="icon" type="image/png" href="/assets/page-agent-64.png" />
+		<title>Page Agent Hub</title>
+	</head>
+	<body>
+		<div id="root"></div>
+		<script type="module" src="./main.tsx"></script>
+	</body>
+</html>

packages/extension/src/entrypoints/hub/main.tsx

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+import React from 'react'
+import ReactDOM from 'react-dom/client'
+
+import { ErrorBoundary } from '@/components/ErrorBoundary'
+
+import App from './App'
+
+import '@/assets/index.css'
+
+const syncDarkMode = () => {
+	document.documentElement.classList.toggle(
+		'dark',
+		matchMedia('(prefers-color-scheme: dark)').matches
+	)
+}
+syncDarkMode()
+matchMedia('(prefers-color-scheme: dark)').addEventListener('change', syncDarkMode)
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+	<React.StrictMode>
+		<ErrorBoundary>
+			<App />
+		</ErrorBoundary>
+	</React.StrictMode>
+)