diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5a244c3..f051cdb2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,12 @@
 
 本项目所有重要变更记录于此。格式参考 [Keep a Changelog](https://keepachangelog.com/zh-CN/1.1.0/)，遵循 [语义化版本](https://semver.org/lang/zh-CN/)。
 
+## [Unreleased]
+
+### Fixed
+
+- **快手 ASR 接口下线后用户看到无信息量的「未知错误」**：快手官方已永久关闭 `ai.kuaishou.com/api/effects/subtitle_generate`（返回 `code=501, msg=效果subtitle_generate禁用`），旧实现默默地把这条 501 错误冒泡出去，前端只能展示「快手 API 返回错误: 未知错误」之类的笼统提示，用户无从得知是该接口本身已下线。`KuaishouTranscriber._submit` 现在直接在入口处抛 `RuntimeError` 并提示用户切换到 bcut 或 Faster Whisper，避免无谓的上传带宽消耗。
+
 ## [2.4.4] - 2026-06-23
 
 ### Security
diff --git a/backend/app/transcriber/kuaishou.py b/backend/app/transcriber/kuaishou.py
index e2846b1f..6c1fe11b 100644
--- a/backend/app/transcriber/kuaishou.py
+++ b/backend/app/transcriber/kuaishou.py
@@ -26,39 +26,12 @@ def _load_file(self, file_path: str) -> bytes:
 
     def _submit(self, file_path: str) -> dict:
         """提交识别请求"""
-        try:
-            file_binary = self._load_file(file_path)
-            
-            payload = {
-                "typeId": "1"
-            }
-            
-            # 使用文件名作为上传文件名
-            file_name = os.path.basename(file_path)
-            files = [('file', (file_name, file_binary, 'audio/mpeg'))]
-            
-            logger.info(f"开始向快手API提交请求，文件: {file_name}")
-            response = requests.post(self.API_URL, data=payload, files=files, timeout=300)
-            response.raise_for_status()  # 检查HTTP错误
-            
-            result = response.json()
-            print('result',result)
-            # 检查快手API返回是否包含错误
-            if "data" not in result or result.get("code", 0) != 0:
-                error_msg = f"快手API返回错误: {result.get('message', '未知错误')}"
-                logger.error(error_msg)
-                raise Exception(error_msg)
-                
-            return result
-            
-        except requests.exceptions.RequestException as e:
-            error_msg = f"快手ASR请求网络错误: {str(e)}"
-            logger.error(error_msg)
-            raise
-        except Exception as e:
-            error_msg = f"快手ASR请求处理错误: {str(e)}"
-            logger.error(error_msg)
-            raise
+        # 快手 ASR API 已于 2025 年永久关停 (code=501, msg="效果subtitle_generate禁用")，
+        # 请使用 bcut（B站必剪）或 fast-whisper（本地）替代。
+        raise RuntimeError(
+            "快手 ASR 转写接口已永久关停（快手官方已禁用 subtitle_generate API）。"
+            "请在「设置 → 音频转写配置」中将转写引擎切换为「必剪(bcut)」或「Faster Whisper(本地)」。"
+        )
 
     @timeit
     def transcript(self, file_path: str) -> TranscriptResult:
diff --git a/backend/tests/test_kuaishou_disabled.py b/backend/tests/test_kuaishou_disabled.py
new file mode 100644
index 00000000..4ca744a5
--- /dev/null
+++ b/backend/tests/test_kuaishou_disabled.py
@@ -0,0 +1,49 @@
+"""
+Coverage for the Kuaishou ASR disabled-state guard.
+
+Background: 快手 (Kuaishou) 关闭了对外开放的 subtitle_generate 语音识别接口,
+任何调用都会立刻返回 ``{"code": 501, "msg": "效果subtitle_generate禁用"}``。
+旧实现默默地把这条错误抛出去,前端没有针对性的提示,用户只能从
+"未知错误" 里猜原因。
+
+本次改动在 KuaishouTranscriber._submit 开头直接抛带操作指引的
+``RuntimeError``,而不是花时间把文件 POST 上去再被 501 拒掉。
+"""
+import pytest
+
+from app.transcriber import kuaishou as kuaishou_module
+from app.transcriber.kuaishou import KuaishouTranscriber
+
+
+def test_kuaishou_submit_raises_clear_error(tmp_path):
+    """_submit should raise immediately with a message that names the replacement engines."""
+    f = tmp_path / "audio.mp3"
+    f.write_bytes(b"fake")
+
+    t = KuaishouTranscriber()
+    with pytest.raises(RuntimeError) as exc:
+        t._submit(str(f))
+    msg = str(exc.value)
+    # 用户需要能根据这条提示自助切换到 bcut / faster-whisper
+    assert "快手" in msg or "Kuaishou" in msg
+    assert "已" in msg or "关闭" in msg or "禁用" in msg
+    assert "bcut" in msg or "必剪" in msg
+    assert "whisper" in msg.lower() or "Faster Whisper" in msg
+
+
+def test_kuaishou_submit_does_not_make_network_call(monkeypatch, tmp_path):
+    """短路上线后,不应再发起网络请求 (避免无谓的上传带宽消耗)."""
+    called = {"n": 0}
+
+    def fake_post(*args, **kwargs):
+        called["n"] += 1
+        raise AssertionError("submit() should not reach requests.post after the shutdown guard")
+
+    monkeypatch.setattr(kuaishou_module.requests, "post", fake_post)
+    f = tmp_path / "audio.mp3"
+    f.write_bytes(b"fake")
+
+    t = KuaishouTranscriber()
+    with pytest.raises(RuntimeError):
+        t._submit(str(f))
+    assert called["n"] == 0