refactor: 优化脚本设置与配置更新逻辑

重构 script_settings.py 中的脚本模式状态处理逻辑，完善会话状态 fallback 与默认值处理，新增 required 参数修复空选择问题。新增 update_app_config_if_changed 工具函数，仅在配置值实际变更时更新配置，替换基础设置中多处直接修改配置的代码，统一逻辑并减少不必要的状态更新。

webui/components/basic_settings.py

@@ -140,6 +140,15 @@ def show_config_validation_errors(errors: list):
             st.error(error)
 
 
+def update_app_config_if_changed(key: str, value) -> bool:
+    """Update app config only when the value really changed."""
+    if config.app.get(key) == value:
+        return False
+
+    config.app[key] = value
+    return True
+
+
 def render_basic_settings(tr):
     """渲染基础设置面板"""
     with st.expander(tr("Basic Settings"), expanded=False):
@@ -546,9 +555,11 @@ def render_vision_llm_settings(tr):
         # 这里的验证逻辑可能需要微调，因为我们现在是自动组合的
         is_valid, error_msg = validate_openai_compatible_model_name(st_vision_model_name, "视频分析")
         if is_valid:
-            config.app["vision_openai_model_name"] = st_vision_model_name
+            config_changed |= update_app_config_if_changed(
+                "vision_openai_model_name",
+                st_vision_model_name
+            )
             st.session_state["vision_openai_model_name"] = st_vision_model_name
-            config_changed = True
         else:
             validation_errors.append(error_msg)
 
@@ -556,9 +567,11 @@ def render_vision_llm_settings(tr):
     if st_vision_api_key:
         is_valid, error_msg = validate_api_key(st_vision_api_key, "视频分析")
         if is_valid:
-            config.app["vision_openai_api_key"] = st_vision_api_key
+            config_changed |= update_app_config_if_changed(
+                "vision_openai_api_key",
+                st_vision_api_key
+            )
             st.session_state["vision_openai_api_key"] = st_vision_api_key
-            config_changed = True
         else:
             validation_errors.append(error_msg)
 
@@ -566,9 +579,11 @@ def render_vision_llm_settings(tr):
     if st_vision_base_url:
         is_valid, error_msg = validate_base_url(st_vision_base_url, "视频分析")
         if is_valid:
-            config.app["vision_openai_base_url"] = st_vision_base_url
+            config_changed |= update_app_config_if_changed(
+                "vision_openai_base_url",
+                st_vision_base_url
+            )
             st.session_state["vision_openai_base_url"] = st_vision_base_url
-            config_changed = True
         else:
             validation_errors.append(error_msg)
 
@@ -804,9 +819,11 @@ def render_text_llm_settings(tr):
     if st_text_model_name:
         is_valid, error_msg = validate_openai_compatible_model_name(st_text_model_name, "文案生成")
         if is_valid:
-            config.app["text_openai_model_name"] = st_text_model_name
+            text_config_changed |= update_app_config_if_changed(
+                "text_openai_model_name",
+                st_text_model_name
+            )
             st.session_state["text_openai_model_name"] = st_text_model_name
-            text_config_changed = True
         else:
             text_validation_errors.append(error_msg)
 
@@ -814,9 +831,11 @@ def render_text_llm_settings(tr):
     if st_text_api_key:
         is_valid, error_msg = validate_api_key(st_text_api_key, "文案生成")
         if is_valid:
-            config.app["text_openai_api_key"] = st_text_api_key
+            text_config_changed |= update_app_config_if_changed(
+                "text_openai_api_key",
+                st_text_api_key
+            )
             st.session_state["text_openai_api_key"] = st_text_api_key
-            text_config_changed = True
         else:
             text_validation_errors.append(error_msg)
 
@@ -824,9 +843,11 @@ def render_text_llm_settings(tr):
     if st_text_base_url:
         is_valid, error_msg = validate_base_url(st_text_base_url, "文案生成")
         if is_valid:
-            config.app["text_openai_base_url"] = st_text_base_url
+            text_config_changed |= update_app_config_if_changed(
+                "text_openai_base_url",
+                st_text_base_url
+            )
             st.session_state["text_openai_base_url"] = st_text_base_url
-            text_config_changed = True
         else:
             text_validation_errors.append(error_msg)
 

webui/components/script_settings.py

@@ -56,11 +56,6 @@ def render_script_file(tr, params):
     MODE_SHORT = "short"
     MODE_SUMMARY = "summary"
 
-    # 处理保存脚本后的模式切换（必须在 widget 实例化之前）
-    if st.session_state.get('_switch_to_file_mode'):
-        st.session_state['script_mode_selection'] = tr("Select/Upload Script")
-        del st.session_state['_switch_to_file_mode']
-
     # 模式选项映射
     mode_options = {
         tr("Select/Upload Script"): MODE_FILE,
@@ -88,6 +83,18 @@ def render_script_file(tr, params):
     # 1. 渲染功能选择下拉框
     # 使用 segmented_control 替代 selectbox，提供更好的视觉体验
     default_mode_label = mode_keys[default_index]
+    default_mode = mode_options[default_mode_label]
+
+    if st.session_state.get('_switch_to_file_mode'):
+        st.session_state['script_mode_selection'] = tr("Select/Upload Script")
+        del st.session_state['_switch_to_file_mode']
+    elif (
+        'script_mode_selection' not in st.session_state
+        or st.session_state['script_mode_selection'] not in mode_options
+    ):
+        st.session_state['script_mode_selection'] = default_mode_label
+    elif mode_options[st.session_state['script_mode_selection']] != default_mode:
+        st.session_state['script_mode_selection'] = default_mode_label
     
     # 定义回调函数来处理状态更新
     def update_script_mode():
@@ -107,12 +114,12 @@ def render_script_file(tr, params):
     selected_mode_label = st.segmented_control(
         tr("Video Type"),
         options=mode_keys,
-        default=default_mode_label,
         key="script_mode_selection",
-        on_change=update_script_mode
+        on_change=update_script_mode,
+        required=True
     )
     
-    # 处理未选择的情况（虽然有default，但在某些交互下可能为空）
+    # 处理旧状态为空的兜底情况
     if not selected_mode_label:
         selected_mode_label = default_mode_label