diff --git a/web/src/App.tsx b/web/src/App.tsx
index 066389f..8a55eb3 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -1,3 +1,4 @@
+import { useEffect } from "react";
 import { Toaster } from "sonner";
 import { HistoryList } from "./components/HistoryList";
 import { MicButton } from "./components/MicButton";
@@ -5,13 +6,36 @@ import { PreviewBox } from "./components/PreviewBox";
 import { StatusBadge } from "./components/StatusBadge";
 import { useRecorder } from "./hooks/useRecorder";
 import { useWebSocket } from "./hooks/useWebSocket";
+import { useAppStore } from "./stores/app-store";
 
 export function App() {
-	const { sendJSON, sendBinary } = useWebSocket();
-	const { startRecording, stopRecording } = useRecorder({
-		sendJSON,
-		sendBinary,
+	const { requestStart, sendStop, sendPaste, sendAudioFrame } = useWebSocket();
+	const { prewarm, startRecording, stopRecording } = useRecorder({
+		requestStart,
+		sendStop,
+		sendAudioFrame,
 	});
+	const micReady = useAppStore((s) => s.micReady);
+
+	useEffect(() => {
+		const forceStopOnBackground = () => {
+			const state = useAppStore.getState();
+			if (state.recording || state.pendingStart) {
+				stopRecording();
+			}
+		};
+
+		const onVisibility = () => {
+			if (document.hidden) forceStopOnBackground();
+		};
+
+		document.addEventListener("visibilitychange", onVisibility);
+		window.addEventListener("pagehide", forceStopOnBackground);
+		return () => {
+			document.removeEventListener("visibilitychange", onVisibility);
+			window.removeEventListener("pagehide", forceStopOnBackground);
+		};
+	}, [stopRecording]);
 
 	return (
 		<>
@@ -24,8 +48,17 @@ export function App() {
 				</header>
 
 				<PreviewBox />
+				{!micReady ? (
+					<button
+						type="button"
+						onClick={() => void prewarm()}
+						className="mb-3 rounded-xl border border-edge bg-surface px-4 py-3 font-medium text-fg text-sm"
+					>
+						{"先点我准备麦克风（首次会弹权限）"}
+					</button>
+				) : null}
 				<MicButton onStart={startRecording} onStop={stopRecording} />
-				<HistoryList sendJSON={sendJSON} />
+				<HistoryList sendPaste={sendPaste} />
 			</div>
 			<Toaster theme="dark" position="bottom-center" />
 		</>
diff --git a/web/src/hooks/useRecorder.ts b/web/src/hooks/useRecorder.ts
index dc32767..a7c1bd4 100644
--- a/web/src/hooks/useRecorder.ts
+++ b/web/src/hooks/useRecorder.ts
@@ -3,71 +3,116 @@ import { useCallback, useRef } from "react";
 import { toast } from "sonner";
 import { useAppStore } from "../stores/app-store";
 
-/**
- * ~200ms frames at 16kHz = 3200 samples.
- * Doubao bigmodel_async recommends 200ms packets for optimal performance.
- */
 const FRAME_LENGTH = 3200;
 
 interface UseRecorderOptions {
-	sendJSON: (obj: Record<string, unknown>) => void;
-	sendBinary: (data: Int16Array) => void;
+	requestStart: () => Promise<string | null>;
+	sendStop: (sessionId: string | null) => void;
+	sendAudioFrame: (sessionId: string, seq: number, data: Int16Array) => boolean;
 }
 
-export function useRecorder({ sendJSON, sendBinary }: UseRecorderOptions) {
+let optionsInitialized = false;
+
+export function useRecorder({
+	requestStart,
+	sendStop,
+	sendAudioFrame,
+}: UseRecorderOptions) {
 	const abortRef = useRef<AbortController | null>(null);
 	const engineRef = useRef<{ onmessage: (e: MessageEvent) => void } | null>(
 		null,
 	);
+	const warmedRef = useRef(false);
+	const audioSeqRef = useRef(1);
 
-	// Keep stable refs so callbacks never go stale
-	const sendJSONRef = useRef(sendJSON);
-	const sendBinaryRef = useRef(sendBinary);
-	sendJSONRef.current = sendJSON;
-	sendBinaryRef.current = sendBinary;
+	const initOptions = useCallback(() => {
+		if (optionsInitialized) return;
+		WebVoiceProcessor.setOptions({
+			frameLength: FRAME_LENGTH,
+			outputSampleRate: 16000,
+		});
+		optionsInitialized = true;
+	}, []);
+
+	const prewarm = useCallback(async (): Promise<boolean> => {
+		if (warmedRef.current) return true;
+		initOptions();
+
+		const warmEngine = {
+			onmessage: () => {},
+		};
+
+		try {
+			await WebVoiceProcessor.subscribe(warmEngine);
+			await WebVoiceProcessor.unsubscribe(warmEngine);
+			warmedRef.current = true;
+			useAppStore.getState().setMicReady(true);
+			return true;
+		} catch (err) {
+			const error = err as Error;
+			toast.error(`麦克风准备失败: ${error.message}`);
+			return false;
+		}
+	}, [initOptions]);
 
 	const startRecording = useCallback(async () => {
 		const store = useAppStore.getState();
-		if (store.recording || store.pendingStart) return;
+		if (store.recording || store.pendingStart || store.stopping) return;
 
 		store.setPendingStart(true);
+		store.setStopping(false);
+
 		const abort = new AbortController();
 		abortRef.current = abort;
 
 		try {
-			// Create an engine that receives Int16Array @ 16kHz from WebVoiceProcessor
+			const warmed = await prewarm();
+			if (!warmed) {
+				store.setPendingStart(false);
+				abortRef.current = null;
+				return;
+			}
+
+			const sessionId = await requestStart();
+			if (!sessionId) {
+				store.setPendingStart(false);
+				abortRef.current = null;
+				toast.error("启动会话失败，请重试");
+				return;
+			}
+
 			const engine = {
 				onmessage: (e: MessageEvent) => {
-					if (e.data.command === "process") {
-						sendBinaryRef.current(e.data.inputFrame as Int16Array);
-					}
+					if (e.data.command !== "process") return;
+					const seq = audioSeqRef.current;
+					audioSeqRef.current += 1;
+					sendAudioFrame(sessionId, seq, e.data.inputFrame as Int16Array);
 				},
 			};
 			engineRef.current = engine;
+			audioSeqRef.current = 1;
 
-			WebVoiceProcessor.setOptions({
-				frameLength: FRAME_LENGTH,
-				outputSampleRate: 16000,
-			});
-
-			// subscribe() handles getUserMedia + AudioContext lifecycle internally.
-			// It checks for closed/suspended AudioContext and re-creates as needed.
 			await WebVoiceProcessor.subscribe(engine);
 
 			if (abort.signal.aborted) {
 				await WebVoiceProcessor.unsubscribe(engine);
 				engineRef.current = null;
+				sendStop(sessionId);
 				store.setPendingStart(false);
+				abortRef.current = null;
 				return;
 			}
 
+			store.setActiveSessionId(sessionId);
 			store.setPendingStart(false);
-			abortRef.current = null;
 			store.setRecording(true);
-			sendJSONRef.current({ type: "start" });
+			store.setStopping(false);
 			store.clearPreview();
+			abortRef.current = null;
 		} catch (err) {
-			useAppStore.getState().setPendingStart(false);
+			store.setPendingStart(false);
+			store.setRecording(false);
+			store.setStopping(false);
 			abortRef.current = null;
 			engineRef.current = null;
 
@@ -86,7 +131,7 @@ export function useRecorder({ sendJSON, sendBinary }: UseRecorderOptions) {
 					toast.error(`麦克风错误: ${error.message}`);
 			}
 		}
-	}, []);
+	}, [prewarm, requestStart, sendAudioFrame, sendStop]);
 
 	const stopRecording = useCallback(() => {
 		const store = useAppStore.getState();
@@ -100,15 +145,16 @@ export function useRecorder({ sendJSON, sendBinary }: UseRecorderOptions) {
 
 		if (!store.recording) return;
 		store.setRecording(false);
+		store.setStopping(true);
+		audioSeqRef.current = 1;
 
 		if (engineRef.current) {
-			// Fire-and-forget: state is already updated, cleanup is async
 			WebVoiceProcessor.unsubscribe(engineRef.current);
 			engineRef.current = null;
 		}
 
-		sendJSONRef.current({ type: "stop" });
-	}, []);
+		sendStop(store.activeSessionId);
+	}, [sendStop]);
 
-	return { startRecording, stopRecording };
+	return { prewarm, startRecording, stopRecording };
 }