diff --git a/BillNote_frontend/src/pages/SettingPage/transcriber.tsx b/BillNote_frontend/src/pages/SettingPage/transcriber.tsx
index e13eb93..17f298c 100644
--- a/BillNote_frontend/src/pages/SettingPage/transcriber.tsx
+++ b/BillNote_frontend/src/pages/SettingPage/transcriber.tsx
@@ -73,6 +73,28 @@ export default function Transcriber() {
   }, [modelStatuses, mlxModelStatuses, fetchModelsStatus])
 
   const handleSave = async () => {
+    // 切到本地 whisper 引擎且选了未下载的模型时，提前 confirm，避免用户保存后到首次任务才发现要下 GB 级模型
+    if (isWhisperType(selectedType)) {
+      const pool = selectedType === 'mlx-whisper' ? mlxModelStatuses : modelStatuses
+      const target = pool.find(m => m.model_size === selectedModelSize)
+      if (target && !target.downloaded && !target.downloading) {
+        const sizeHint: Record<string, string> = {
+          'tiny': '~75MB',
+          'base': '~150MB',
+          'small': '~500MB',
+          'medium': '~1.5GB',
+          'large-v3': '~3GB',
+          'large-v3-turbo': '~1.6GB',
+        }
+        const ok = window.confirm(
+          `选择 ${selectedType} / ${selectedModelSize} 后，首次转写时会下载该模型（${sizeHint[selectedModelSize] || '体积未知'}）。\n` +
+          `网络较差时容易中断；推荐改用 Groq / 必剪 / 快手 等在线引擎。\n\n` +
+          '继续保存吗？',
+        )
+        if (!ok) return
+      }
+    }
+
     setSaving(true)
     try {
       const payload: { transcriber_type: string; whisper_model_size?: string } = {
diff --git a/backend/app/services/transcriber_config_manager.py b/backend/app/services/transcriber_config_manager.py
index d3a69e4..8205372 100644
--- a/backend/app/services/transcriber_config_manager.py
+++ b/backend/app/services/transcriber_config_manager.py
@@ -25,7 +25,12 @@ class TranscriberConfigManager:
             json.dump(data, f, ensure_ascii=False, indent=2)
 
     def get_config(self) -> Dict[str, Any]:
-        """获取当前转写器配置，fallback 到环境变量默认值。"""
+        """获取当前转写器配置，fallback 到环境变量默认值。
+
+        whisper 默认 size 从 'medium' (~1.5GB) 改为 'tiny' (~75MB)：
+        新装用户没主动设置时不应该被首次下载卡住。想要更高精度可在「音频转写配置」
+        页主动切换。
+        """
         data = self._read()
         return {
             "transcriber_type": data.get(
@@ -34,7 +39,7 @@ class TranscriberConfigManager:
             ),
             "whisper_model_size": data.get(
                 "whisper_model_size",
-                os.getenv("WHISPER_MODEL_SIZE", "medium"),
+                os.getenv("WHISPER_MODEL_SIZE", "tiny"),
             ),
         }