fix(chat): remove aggregated default model option

src/pages/ChatPage.tsx

@@ -97,6 +97,10 @@ export default function ChatPage() {
     }
     const a = await AgentAPI.detail(id);
     setAgent(a);
+    const firstModel = parseAgentModels(a.model)[0];
+    if (firstModel) {
+      setOverrides((o) => ({ ...o, model: o.model || firstModel }));
+    }
   };
 
   const loadAgentList = async () => {
@@ -404,15 +408,6 @@ export default function ChatPage() {
     label: modelName
   }));
   const activeModelValue = overrides.model || '';
-  const defaultModelLabel = agentModel || '默认模型';
-  const selectedModelKey = activeModelValue || '__default__';
-  const modelSelectOptions = [
-    {
-      value: '__default__',
-      label: defaultModelLabel
-    },
-    ...modelOptions
-  ];
 
   return (
     <div className="chat-shell">
@@ -650,17 +645,13 @@ export default function ChatPage() {
               <div className="chat-input-toolbar">
                 <div className="chat-input-toolbar-left">
                   <Select
-                    value={selectedModelKey}
+                    value={activeModelValue || undefined}
                     className="chat-model-select"
                     popupMatchSelectWidth={false}
-                    options={modelSelectOptions}
+                    options={modelOptions}
                     suffixIcon={<DownOutlined className="chat-model-select-arrow" />}
-                    onChange={(value) =>
-                      setOverrides((o) => ({
-                        ...o,
-                        model: value === '__default__' ? undefined : String(value)
-                      }))
-                    }
+                    placeholder="选择模型"
+                    onChange={(value) => setOverrides((o) => ({ ...o, model: String(value) }))}
                   />
 
                   <Upload

src/styles.css

@@ -601,6 +601,7 @@ body {
   color: var(--color-text);
   font-weight: 500;
   font-size: 13px;
+  padding: 0 8px;
 }
 
 .chat-model-select .ant-select-selection-placeholder {