docs(ai): clarify saved manual model behavior

docs/content/docs/ai-assistant.cn.mdx

@@ -48,7 +48,7 @@ Desktop 还可以直接调用已安装并登录的：
   <Step>
     ### 选择供应商和模型
 
-    使用预设、兼容 API、自定义端点或本地 CLI。模型列表可发现时从供应商或本地 CLI 读取，也可以手动填写。
+    使用预设、兼容 API、自定义端点或本地 CLI。模型列表可发现时从供应商或本地 CLI 读取，也可以手动填写。手动填写的模型会保存到当前配置；当兼容供应商未提供模型发现接口或发现失败时，已保存的模型仍可选择。
 
   </Step>
   <Step>

docs/content/docs/ai-assistant.mdx

@@ -48,7 +48,7 @@ You can configure the executable path and additional environment variables. CLI
   <Step>
     ### Choose Provider and Model
 
-    Use a preset, compatible API, custom endpoint, or local CLI. Models are discovered from the provider or CLI when possible and can otherwise be entered manually.
+    Use a preset, compatible API, custom endpoint, or local CLI. Models are discovered from the provider or CLI when possible and can otherwise be entered manually. Manually entered models are saved with the current configuration and remain selectable when a compatible provider does not expose model discovery or discovery fails.
 
   </Step>
   <Step>