feat: remove tool chips above input, add Auto model option

- Remove selected-tool chip/tag area above the input textarea; tool
  selection state is now shown only via button highlight in the tools panel
- Add "Auto" as a third model option between Flash and Pro (default)
- Auto maps to "flash" when sent to the backend (which only accepts
  flash|pro)

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

frontend/components/gemini/GeminiChat.tsx

@@ -72,13 +72,16 @@ export function GeminiChat() {
   const [extensions, setExtensions] = useState<Extension[]>(INITIAL_EXTENSIONS);
   const [ticketSummary, setTicketSummary] = useState<TicketSummaryData | null>(null);
   const [activeTools, setActiveTools] = useState<Set<string>>(new Set());
-  const [selectedModel, setSelectedModel] = useState<"flash" | "pro">("pro");
+  const [selectedModel, setSelectedModel] = useState<"flash" | "auto" | "pro">("auto");
   const messagesEndRef = useRef<HTMLDivElement>(null);
   const abortRef = useRef<AbortController | null>(null);
 
   const activeConversation = conversations.find((c) => c.id === activeConvId) ?? null;
   const messages = activeConversation?.messages ?? [];
 
+  // Map UI model to backend model ("auto" -> "flash")
+  const apiModel: "flash" | "pro" = selectedModel === "pro" ? "pro" : "flash";
+
   // 检查工单系统是否已连接
   const ticketSystemConnected = extensions.find((e) => e.id === "ticket")?.connected ?? false;
 
@@ -200,7 +203,7 @@ export function GeminiChat() {
       text,
       streamConvId,
       Array.from(activeTools),
-      selectedModel,
+      apiModel,
       (event) => {
         if (event.type === "token" && event.content) {
           setConversations((prev) =>
@@ -244,7 +247,7 @@ export function GeminiChat() {
         setIsLoading(false);
       }
     );
-  }, [inputValue, isLoading, activeConvId, activeTools, selectedModel]);
+  }, [inputValue, isLoading, activeConvId, activeTools, apiModel]);
 
   const handleRegenerate = useCallback(
     async (msgId: string) => {
@@ -283,7 +286,7 @@ export function GeminiChat() {
         userMsg.content,
         regenConvId,
         Array.from(activeTools),
-        selectedModel,
+        apiModel,
         (event) => {
           if (event.type === "token" && event.content) {
             setConversations((prev) =>
@@ -309,7 +312,7 @@ export function GeminiChat() {
         }
       );
     },
-    [activeConvId, conversations, isLoading, activeTools, selectedModel]
+    [activeConvId, conversations, isLoading, activeTools, apiModel]
   );
 
   const handleSuggestionClick = useCallback((text: string) => {

frontend/components/gemini/GeminiInput.tsx

@@ -10,7 +10,6 @@ import {
   Database,
   FileText,
   Code2,
-  X,
 } from "lucide-react";
 import { cn } from "@/lib/utils";
 
@@ -27,8 +26,8 @@ interface GeminiInputProps {
   isLoading?: boolean;
   activeTools: Set<string>;
   onActiveToolsChange: (tools: Set<string>) => void;
-  selectedModel: "flash" | "pro";
-  onSelectedModelChange: (model: "flash" | "pro") => void;
+  selectedModel: "flash" | "auto" | "pro";
+  onSelectedModelChange: (model: "flash" | "auto" | "pro") => void;
 }
 
 const TOOLS: Tool[] = [
@@ -77,12 +76,6 @@ export function GeminiInput({
     onActiveToolsChange(next);
   };
 
-  const removeTool = (id: string) => {
-    const next = new Set(activeTools);
-    next.delete(id);
-    onActiveToolsChange(next);
-  };
-
   const canSend = value.trim().length > 0 && !isLoading;
 
   const handleFileUpload = (e: React.ChangeEvent<HTMLInputElement>) => {
@@ -98,33 +91,6 @@ export function GeminiInput({
       <div className="max-w-3xl mx-auto px-4 pointer-events-auto">
         {/* Input container */}
         <div className="bg-[var(--gem-surface)] border border-[var(--gem-border)] rounded-3xl shadow-lg focus-within:border-[var(--gem-border-hover)] transition-colors duration-150">
-          {/* Selected tools chips (auto show when has active tools) */}
-          {activeTools.size > 0 && (
-            <div className="flex items-center gap-2 px-4 pt-3 pb-1 flex-wrap">
-              {Array.from(activeTools).map((toolId) => {
-                const tool = TOOLS.find((t) => t.id === toolId);
-                if (!tool) return null;
-                const Icon = tool.icon;
-                return (
-                  <span
-                    key={tool.id}
-                    className="flex items-center gap-2 px-2.5 py-1.5 rounded-lg text-xs font-medium bg-[var(--gem-blue)] text-white border border-[var(--gem-blue)]"
-                  >
-                    <Icon size={14} />
-                    <span>{tool.label}</span>
-                    <button
-                      onClick={() => removeTool(tool.id)}
-                      className="ml-1 hover:opacity-80 transition-opacity cursor-pointer"
-                      aria-label={`移除${tool.label}`}
-                    >
-                      <X size={12} />
-                    </button>
-                  </span>
-                );
-              })}
-            </div>
-          )}
-
           {/* Main input row */}
           <div className="flex items-end gap-2 px-4 py-3">
             {/* Left: File upload button */}
@@ -218,6 +184,18 @@ export function GeminiInput({
             >
               Flash
             </button>
+            <button
+              onClick={() => onSelectedModelChange("auto")}
+              className={cn(
+                "px-3 py-1.5 rounded-full text-xs font-medium transition-all duration-150 cursor-pointer",
+                selectedModel === "auto"
+                  ? "bg-[var(--gem-blue)] text-white"
+                  : "bg-[var(--gem-surface-2)] text-[var(--gem-text-muted)] hover:bg-[var(--gem-surface-3)] hover:text-[var(--gem-text)]"
+              )}
+              aria-pressed={selectedModel === "auto"}
+            >
+              Auto
+            </button>
             <button
               onClick={() => onSelectedModelChange("pro")}
               className={cn(