fix: 标签文件下载失败时给出明确错误提示

internal/hentai/server.py

@@ -140,8 +140,9 @@ def _ensure_model(model_dir):
             _download_file(HF_TAGS_URL, tags_path)
             print("=== 标签文件下载完成", flush=True)
         except Exception as exc:
-            print("=== 标签文件下载失败: %s" % exc, flush=True)
-            return None, None
+            # 标签文件下载失败不影响模型运行，只是无法解析输出标签
+            print("=== 警告: 标签文件下载失败，将无法解析输出标签: %s" % exc, flush=True)
+            tags_path = ""  # 标记标签文件不可用，但仍返回模型路径
 
     return model_path, tags_path
 
@@ -180,6 +181,10 @@ def get_session():
     global _session
     if "_session" not in dir() or _session is None:
         model_path, tags_path = _ensure_model(MODEL_DIR)
+        if not model_path:
+            raise RuntimeError("wd-tagger 模型不可用")
+        if not tags_path:
+            raise RuntimeError("wd-tagger 标签文件不可用，无法解析输出。请手动下载 %s 到 %s" % (TAGS_FILENAME, os.path.join(MODEL_DIR, MODEL_DIR_NAME)))
         _load_tags(tags_path)
         _session = _new_session(model_path)
     return _session