feat(ext): hub protocol

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

@@ -0,0 +1,219 @@
+/**
+ * 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 }
+}