diff --git a/webui/src/components/thread/ThreadComposer.tsx b/webui/src/components/thread/ThreadComposer.tsx
index 23757353..48208b40 100644
--- a/webui/src/components/thread/ThreadComposer.tsx
+++ b/webui/src/components/thread/ThreadComposer.tsx
@@ -97,6 +97,8 @@ import { cn } from "@/lib/utils";
 
 const VOICE_SHORTCUT_CODE = "KeyD";
 const VOICE_SHORTCUT_ARIA = "Control+Shift+D";
+const VOICE_ERROR_VISIBLE_MS = 3_500;
+const VOICE_ERROR_FADE_MS = 500;
 type VoiceShortcutPlatform = "apple" | "chromeos" | "linux" | "other" | "windows";
 
 function formatBytes(n: number): string {
@@ -819,6 +821,7 @@ export function ThreadComposer({
   const { t } = useTranslation();
   const [value, setValue] = useState("");
   const [inlineError, setInlineError] = useState<string | null>(null);
+  const [voiceErrorFading, setVoiceErrorFading] = useState(false);
   const [slashMenuDismissed, setSlashMenuDismissed] = useState(false);
   const [selectedCommandIndex, setSelectedCommandIndex] = useState(0);
   const [cliAppMenuDismissed, setCliAppMenuDismissed] = useState(false);
@@ -839,6 +842,7 @@ export function ThreadComposer({
   const skipNextQueuedFlushRef = useRef(false);
   const skipQueuedPromptPersistRef = useRef(false);
   const voiceShortcutDownRef = useRef(false);
+  const voiceErrorFadeTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
   const isHero = variant === "hero";
   const voiceShortcutLabel = useMemo(getVoiceShortcutLabel, []);
   const queuedPromptStorageKey = useMemo(
@@ -1287,10 +1291,28 @@ export function ThreadComposer({
     resizeTextarea();
   }, [resizeTextarea]);
 
-  const clearInlineError = useCallback(() => setInlineError(null), []);
+  const clearVoiceErrorTimers = useCallback(() => {
+    if (voiceErrorFadeTimerRef.current !== null) clearTimeout(voiceErrorFadeTimerRef.current);
+    voiceErrorFadeTimerRef.current = null;
+  }, []);
+  const clearInlineError = useCallback(() => {
+    clearVoiceErrorTimers();
+    setVoiceErrorFading(false);
+    setInlineError(null);
+  }, [clearVoiceErrorTimers]);
   const setVoiceError = useCallback((key: VoiceRecorderErrorKey) => {
+    clearVoiceErrorTimers();
+    setVoiceErrorFading(false);
     setInlineError(t(`thread.composer.voiceErrors.${key}`));
-  }, [t]);
+    voiceErrorFadeTimerRef.current = setTimeout(() => {
+      setVoiceErrorFading(true);
+      voiceErrorFadeTimerRef.current = setTimeout(() => {
+        setInlineError(null);
+        setVoiceErrorFading(false);
+        voiceErrorFadeTimerRef.current = null;
+      }, VOICE_ERROR_FADE_MS);
+    }, VOICE_ERROR_VISIBLE_MS);
+  }, [clearVoiceErrorTimers, t]);
   const voiceRecorder = useVoiceRecorder({
     disabled,
     onClearError: clearInlineError,
@@ -1300,6 +1322,8 @@ export function ThreadComposer({
     wantsWav: transcriptionProvider === "xiaomi_mimo",
   });
 
+  useEffect(() => () => clearVoiceErrorTimers(), [clearVoiceErrorTimers]);
+
   useEffect(() => {
     if (!onTranscribeAudio) return;
 
@@ -1907,8 +1931,9 @@ export function ThreadComposer({
           <div
             role="alert"
             className={cn(
-              "mx-3 mb-1 rounded-md border border-destructive/40 bg-destructive/8 px-2.5 py-1",
-              "text-[11.5px] font-medium text-destructive",
+              "mx-3 mb-1 max-h-10 overflow-hidden rounded-md border border-destructive/40 bg-destructive/8 px-2.5 py-1",
+              "text-[11.5px] font-medium text-destructive transition-[max-height,margin,padding,opacity] duration-500 ease-out",
+              voiceErrorFading && "mb-0 max-h-0 border-transparent py-0 opacity-0",
             )}
           >
             {inlineError}
diff --git a/webui/src/hooks/useVoiceRecorder.ts b/webui/src/hooks/useVoiceRecorder.ts
index 26803f3d..4b0da850 100644
--- a/webui/src/hooks/useVoiceRecorder.ts
+++ b/webui/src/hooks/useVoiceRecorder.ts
@@ -29,6 +29,7 @@ const VOICE_MIME_CANDIDATES = [
 export type VoiceRecorderState = "idle" | "recording" | "transcribing";
 export type VoiceRecorderErrorKey =
   | "failed"
+  | "noDevice"
   | "noInput"
   | "notConfigured"
   | "permission"
@@ -181,14 +182,17 @@ export function useVoiceRecorder({
 
   const startRecording = useCallback(async () => {
     if (!onTranscribeAudio || state !== "idle" || startPendingRef.current) return;
-    if (!navigator.mediaDevices?.getUserMedia || typeof MediaRecorder === "undefined") {
+    onClearError();
+    const mediaDevices = navigator.mediaDevices;
+    const MediaRecorderCtor = mediaRecorderConstructor();
+    if (!mediaDevices?.getUserMedia || !MediaRecorderCtor) {
       onError("unsupported");
       return;
     }
     startPendingRef.current = true;
     try {
-      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
-      const recorder = new MediaRecorder(stream, mediaRecorderOptions());
+      const stream = await mediaDevices.getUserMedia({ audio: true });
+      const recorder = new MediaRecorderCtor(stream, mediaRecorderOptions(MediaRecorderCtor));
       chunksRef.current = [];
       streamRef.current = stream;
       mediaRecorderRef.current = recorder;
@@ -251,10 +255,10 @@ export function useVoiceRecorder({
         noInputHintVisibleRef.current = true;
         onError("noInput");
       }, VOICE_NO_INPUT_HINT_MS);
-    } catch {
+    } catch (error) {
       cleanupRecording();
       setState("idle");
-      onError("permission");
+      onError(recordingErrorKey(error));
     }
   }, [
     cleanupRecording,
@@ -370,12 +374,21 @@ function clearTimer(ref: { current: ReturnType<typeof setTimeout> | null }) {
   }
 }
 
-function mediaRecorderOptions(): MediaRecorderOptions | undefined {
-  if (typeof MediaRecorder === "undefined") return undefined;
-  const mimeType = VOICE_MIME_CANDIDATES.find((type) => MediaRecorder.isTypeSupported(type));
+function mediaRecorderOptions(MediaRecorderCtor: MediaRecorderConstructor): MediaRecorderOptions | undefined {
+  const mimeType = VOICE_MIME_CANDIDATES.find((type) => MediaRecorderCtor.isTypeSupported?.(type));
   return mimeType ? { mimeType } : undefined;
 }
 
+type MediaRecorderConstructor = typeof MediaRecorder;
+
+function mediaRecorderConstructor(): MediaRecorderConstructor | undefined {
+  if (typeof window === "undefined") return undefined;
+  const browserWindow = window as Window & {
+    MediaRecorder?: MediaRecorderConstructor;
+  };
+  return browserWindow.MediaRecorder;
+}
+
 function formatVoiceElapsed(ms: number): string {
   const seconds = Math.max(0, Math.floor(ms / 1000));
   const minutes = Math.floor(seconds / 60);
@@ -510,3 +523,9 @@ function transcriptionErrorKey(error: unknown): VoiceRecorderErrorKey {
   if (detail === "duration") return "tooLong";
   return "failed";
 }
+
+function recordingErrorKey(error: unknown): VoiceRecorderErrorKey {
+  const name = error instanceof Error ? error.name : "";
+  if (name === "NotFoundError") return "noDevice";
+  return "permission";
+}
diff --git a/webui/src/i18n/locales/en/common.json b/webui/src/i18n/locales/en/common.json
index dec2ea21..03279618 100644
--- a/webui/src/i18n/locales/en/common.json
+++ b/webui/src/i18n/locales/en/common.json
@@ -977,11 +977,12 @@
       },
       "voiceErrors": {
         "unsupported": "Voice input is not supported in this browser.",
-        "permission": "Microphone permission is required.",
+        "permission": "Allow microphone access in the address bar, then retry.",
         "notConfigured": "Configure a transcription provider first.",
         "tooLong": "Recording is too long.",
         "tooShort": "Hold a little longer to record voice.",
         "noInput": "No microphone input detected.",
+        "noDevice": "No microphone was found. Connect a microphone and try again.",
         "failed": "Could not transcribe audio."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/es/common.json b/webui/src/i18n/locales/es/common.json
index 89defe57..d6631ec5 100644
--- a/webui/src/i18n/locales/es/common.json
+++ b/webui/src/i18n/locales/es/common.json
@@ -964,11 +964,12 @@
       },
       "voiceErrors": {
         "unsupported": "Este navegador no admite entrada de voz.",
-        "permission": "Se requiere permiso de micrófono.",
+        "permission": "Permite el micrófono en la barra de direcciones y vuelve a intentarlo.",
         "notConfigured": "Configura primero un proveedor de transcripción.",
         "tooLong": "La grabación es demasiado larga.",
         "tooShort": "Mantén pulsado un poco más para grabar voz.",
         "noInput": "No se detectó entrada del micrófono.",
+        "noDevice": "No se encontró ningún micrófono. Conéctalo y vuelve a intentarlo.",
         "failed": "No se pudo transcribir el audio."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/fr/common.json b/webui/src/i18n/locales/fr/common.json
index 236b95de..b0e50aea 100644
--- a/webui/src/i18n/locales/fr/common.json
+++ b/webui/src/i18n/locales/fr/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "La saisie vocale n'est pas prise en charge par ce navigateur.",
-        "permission": "L'autorisation du microphone est requise.",
+        "permission": "Autorisez le microphone dans la barre d'adresse, puis réessayez.",
         "notConfigured": "Configurez d'abord un fournisseur de transcription.",
         "tooLong": "L'enregistrement est trop long.",
         "tooShort": "Maintenez un peu plus longtemps pour enregistrer la voix.",
         "noInput": "Aucune entrée microphone détectée.",
+        "noDevice": "Aucun microphone trouvé. Connectez-en un, puis réessayez.",
         "failed": "Impossible de transcrire l'audio."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/id/common.json b/webui/src/i18n/locales/id/common.json
index aedb7866..e40f154c 100644
--- a/webui/src/i18n/locales/id/common.json
+++ b/webui/src/i18n/locales/id/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "Input suara tidak didukung di browser ini.",
-        "permission": "Izin mikrofon diperlukan.",
+        "permission": "Izinkan mikrofon di bilah alamat, lalu coba lagi.",
         "notConfigured": "Konfigurasikan penyedia transkripsi terlebih dahulu.",
         "tooLong": "Rekaman terlalu panjang.",
         "tooShort": "Tahan sedikit lebih lama untuk merekam suara.",
         "noInput": "Tidak ada input mikrofon yang terdeteksi.",
+        "noDevice": "Mikrofon tidak ditemukan. Hubungkan mikrofon lalu coba lagi.",
         "failed": "Tidak dapat mentranskripsi audio."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/ja/common.json b/webui/src/i18n/locales/ja/common.json
index 231f5ff4..31fd0705 100644
--- a/webui/src/i18n/locales/ja/common.json
+++ b/webui/src/i18n/locales/ja/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "このブラウザーは音声入力に対応していません。",
-        "permission": "マイクの許可が必要です。",
+        "permission": "アドレスバーでマイクを許可してから再試行してください。",
         "notConfigured": "先に文字起こしプロバイダーを設定してください。",
         "tooLong": "録音が長すぎます。",
         "tooShort": "もう少し長く録音してください。",
         "noInput": "マイク入力が検出されませんでした。",
+        "noDevice": "マイクが見つかりません。接続して再試行してください。",
         "failed": "音声を文字起こしできませんでした。"
       },
       "slash": {
diff --git a/webui/src/i18n/locales/ko/common.json b/webui/src/i18n/locales/ko/common.json
index 8e21ffe3..2fbeef81 100644
--- a/webui/src/i18n/locales/ko/common.json
+++ b/webui/src/i18n/locales/ko/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "이 브라우저는 음성 입력을 지원하지 않습니다.",
-        "permission": "마이크 권한이 필요합니다.",
+        "permission": "주소 표시줄에서 마이크를 허용한 후 다시 시도하세요.",
         "notConfigured": "먼저 음성 변환 제공업체를 설정하세요.",
         "tooLong": "녹음 시간이 너무 깁니다.",
         "tooShort": "음성을 녹음하려면 조금 더 길게 눌러 주세요.",
         "noInput": "마이크 입력이 감지되지 않았습니다.",
+        "noDevice": "마이크를 찾을 수 없습니다. 연결 후 다시 시도하세요.",
         "failed": "오디오를 변환하지 못했습니다."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/pt-BR/common.json b/webui/src/i18n/locales/pt-BR/common.json
index f2899d01..420e6d33 100644
--- a/webui/src/i18n/locales/pt-BR/common.json
+++ b/webui/src/i18n/locales/pt-BR/common.json
@@ -977,11 +977,12 @@
       },
       "voiceErrors": {
         "unsupported": "A entrada de voz não é compatível com este navegador.",
-        "permission": "É necessária permissão do microfone.",
+        "permission": "Permita o microfone na barra de endereço e tente novamente.",
         "notConfigured": "Configure primeiro um provedor de transcrição.",
         "tooLong": "A gravação é longa demais.",
         "tooShort": "Segure um pouco mais para gravar voz.",
         "noInput": "Não foi detectada entrada do microfone.",
+        "noDevice": "Nenhum microfone encontrado. Conecte um e tente novamente.",
         "failed": "Não foi possível transcrever o áudio."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/vi/common.json b/webui/src/i18n/locales/vi/common.json
index 152c5b32..451c8aa6 100644
--- a/webui/src/i18n/locales/vi/common.json
+++ b/webui/src/i18n/locales/vi/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "Trình duyệt này không hỗ trợ nhập bằng giọng nói.",
-        "permission": "Cần quyền truy cập micrô.",
+        "permission": "Cho phép micrô trong thanh địa chỉ rồi thử lại.",
         "notConfigured": "Hãy cấu hình nhà cung cấp chép lời trước.",
         "tooLong": "Bản ghi âm quá dài.",
         "tooShort": "Giữ lâu hơn một chút để ghi âm giọng nói.",
         "noInput": "Không phát hiện đầu vào micrô.",
+        "noDevice": "Không tìm thấy micrô. Hãy kết nối rồi thử lại.",
         "failed": "Không thể chép lời âm thanh."
       },
       "slash": {
diff --git a/webui/src/i18n/locales/zh-CN/common.json b/webui/src/i18n/locales/zh-CN/common.json
index 6331fcbc..8325e87f 100644
--- a/webui/src/i18n/locales/zh-CN/common.json
+++ b/webui/src/i18n/locales/zh-CN/common.json
@@ -976,11 +976,12 @@
       },
       "voiceErrors": {
         "unsupported": "当前浏览器不支持语音输入。",
-        "permission": "需要麦克风权限。",
+        "permission": "请在地址栏允许麦克风后重试。",
         "notConfigured": "请先配置转写提供商。",
         "tooLong": "录音时间太长。",
         "tooShort": "请稍微多录一会儿。",
         "noInput": "没有检测到麦克风输入。",
+        "noDevice": "没有找到可用的麦克风。请连接麦克风后重试。",
         "failed": "语音转写失败。"
       },
       "slash": {
diff --git a/webui/src/i18n/locales/zh-TW/common.json b/webui/src/i18n/locales/zh-TW/common.json
index 7a563c58..ec1e5c83 100644
--- a/webui/src/i18n/locales/zh-TW/common.json
+++ b/webui/src/i18n/locales/zh-TW/common.json
@@ -963,11 +963,12 @@
       },
       "voiceErrors": {
         "unsupported": "目前瀏覽器不支援語音輸入。",
-        "permission": "需要麥克風權限。",
+        "permission": "請在網址列允許麥克風後重試。",
         "notConfigured": "請先設定轉寫供應商。",
         "tooLong": "錄音時間太長。",
         "tooShort": "請延長錄音時間。",
         "noInput": "沒有偵測到麥克風輸入。",
+        "noDevice": "找不到可用的麥克風，請連接後重試。",
         "failed": "語音轉寫失敗。"
       },
       "slash": {
diff --git a/webui/src/tests/thread-composer.test.tsx b/webui/src/tests/thread-composer.test.tsx
index 1fa83010..e47c1a25 100644
--- a/webui/src/tests/thread-composer.test.tsx
+++ b/webui/src/tests/thread-composer.test.tsx
@@ -439,6 +439,49 @@ describe("ThreadComposer", () => {
     await waitFor(() => expect(screen.getByLabelText("Message input")).toHaveValue("one recording"));
   });
 
+  it("distinguishes a missing microphone from a blocked permission", async () => {
+    const { getUserMedia } = mockVoiceRecorder();
+    getUserMedia.mockRejectedValue(Object.assign(new Error("no microphone"), {
+      name: "NotFoundError",
+    }));
+    render(
+      <ThreadComposer
+        onSend={vi.fn()}
+        onTranscribeAudio={vi.fn(async () => "unused")}
+        placeholder="Type your message..."
+      />,
+    );
+
+    fireEvent.click(screen.getByRole("button", { name: "Voice input" }));
+
+    await waitFor(() => {
+      expect(screen.getByText("No microphone was found. Connect a microphone and try again.")).toBeInTheDocument();
+    });
+  });
+
+  it("clears a previous voice error when retrying microphone access", async () => {
+    const { getUserMedia } = mockVoiceRecorder();
+    getUserMedia.mockRejectedValueOnce(new Error("permission denied"));
+    const onTranscribeAudio = vi.fn(async () => "voice retry");
+    render(
+      <ThreadComposer
+        onSend={vi.fn()}
+        onTranscribeAudio={onTranscribeAudio}
+        placeholder="Type your message..."
+      />,
+    );
+
+    const voiceButton = screen.getByRole("button", { name: "Voice input" });
+    fireEvent.click(voiceButton);
+    await waitFor(() => expect(screen.getByText("Allow microphone access in the address bar, then retry.")).toBeInTheDocument());
+
+    fireEvent.click(voiceButton);
+
+    await waitFor(() => expect(screen.queryByText("Allow microphone access in the address bar, then retry.")).not.toBeInTheDocument());
+    expect(await screen.findByLabelText("Recording 0:00")).toBeInTheDocument();
+    fireEvent.click(await screen.findByRole("button", { name: "Stop recording" }));
+  });
+
   it("supports press-and-hold voice recording", async () => {
     mockVoiceRecorder();
     const onSend = vi.fn();