diff --git a/web/app.js b/web/app.js
index c1ecae7..e8bd0d7 100644
--- a/web/app.js
+++ b/web/app.js
@@ -36,6 +36,8 @@ import audioProcessorUrl from "./audio-processor.js?worker&url";
     ws: null,
     connected: false,
     recording: false,
+    pendingStart: false,
+    startCancelled: false,
     audioCtx: null,
     workletNode: null,
     stream: null,
@@ -185,16 +187,25 @@ import audioProcessorUrl from "./audio-processor.js?worker&url";
     state.audioCtx = audioCtx;
   }
   async function startRecording() {
-    if (state.recording) return;
+    if (state.recording || state.pendingStart) return;
+    state.pendingStart = true;
+    state.startCancelled = false;
     try {
       await initAudio();
+      if (state.startCancelled) { state.pendingStart = false; return; }
       // Ensure AudioContext is running (may suspend between recordings)
       if (state.audioCtx.state === "suspended") {
         await state.audioCtx.resume();
       }
+      if (state.startCancelled) { state.pendingStart = false; return; }
       const stream = await navigator.mediaDevices.getUserMedia({
         audio: { echoCancellation: true, noiseSuppression: true, channelCount: 1 },
       });
+      if (state.startCancelled) {
+        stream.getTracks().forEach((t) => t.stop());
+        state.pendingStart = false;
+        return;
+      }
       state.stream = stream;
       const source = state.audioCtx.createMediaStreamSource(stream);
       const worklet = new AudioWorkletNode(state.audioCtx, "audio-processor");
@@ -208,15 +219,23 @@ import audioProcessorUrl from "./audio-processor.js?worker&url";
       worklet.port.postMessage({ command: "start" });
       // Don't connect worklet to destination (no playback)
       state.workletNode = worklet;
+      state.pendingStart = false;
       state.recording = true;
       sendJSON({ type: "start" });
       micBtn.classList.add("recording");
       setPreview("", false);
     } catch (err) {
+      state.pendingStart = false;
       showToast(`麦克风错误: ${err.message}`);
     }
   }
   function stopRecording() {
+    // Cancel pending async start if still initializing
+    if (state.pendingStart) {
+      state.startCancelled = true;
+      micBtn.classList.remove("recording");
+      return;
+    }
     if (!state.recording) return;
     state.recording = false;
     // Stop worklet