diff --git a/frontend/components/gemini/GeminiChat.tsx b/frontend/components/gemini/GeminiChat.tsx
index 5c4d102..5a4a61e 100644
--- a/frontend/components/gemini/GeminiChat.tsx
+++ b/frontend/components/gemini/GeminiChat.tsx
@@ -18,6 +18,7 @@ import {
   deleteConversation,
   type TicketSummaryData,
   type AttachmentData,
+  type TraceItem,
 } from "@/lib/api";
 
 // ── Types ────────────────────────────────────────────────────────────────────
@@ -63,6 +64,58 @@ const INITIAL_EXTENSIONS: Extension[] = [
   },
 ];
 
+// ── Trace helpers ─────────────────────────────────────────────────────────────
+
+function appendTraceItem(
+  convId: string,
+  msgId: string,
+  item: TraceItem,
+  setConversations: React.Dispatch<React.SetStateAction<Conversation[]>>
+) {
+  setConversations((prev) =>
+    prev.map((c) => {
+      if (c.id !== convId) return c;
+      return {
+        ...c,
+        messages: c.messages.map((m) =>
+          m.id === msgId
+            ? { ...m, traceItems: [...(m.traceItems ?? []), item] }
+            : m
+        ),
+      };
+    })
+  );
+}
+
+function updateTraceItem(
+  convId: string,
+  msgId: string,
+  tool: string,
+  updates: Partial<TraceItem>,
+  setConversations: React.Dispatch<React.SetStateAction<Conversation[]>>
+) {
+  setConversations((prev) =>
+    prev.map((c) => {
+      if (c.id !== convId) return c;
+      return {
+        ...c,
+        messages: c.messages.map((m) => {
+          if (m.id !== msgId) return m;
+          const items = [...(m.traceItems ?? [])];
+          // Update the last running entry for this tool
+          for (let i = items.length - 1; i >= 0; i--) {
+            if (items[i].tool === tool && items[i].itemStatus === "running") {
+              items[i] = { ...items[i], ...updates };
+              break;
+            }
+          }
+          return { ...m, traceItems: items };
+        }),
+      };
+    })
+  );
+}
+
 // ── Main Component ────────────────────────────────────────────────────────────
 export function GeminiChat() {
   const [sidebarOpen, setSidebarOpen] = useState(true);
@@ -245,7 +298,8 @@ export function GeminiChat() {
               if (c.id !== streamConvId) return c;
               const exists = c.messages.some((m) => m.id === aiMsgId);
               if (!exists) {
-                // First token: create the assistant message
+                // First token: create the assistant message (preserve accumulated traceItems)
+                const traceItems = c.messages.find((m) => m.id === aiMsgId)?.traceItems ?? [];
                 return {
                   ...c,
                   messages: [
@@ -255,6 +309,7 @@ export function GeminiChat() {
                       role: "assistant" as const,
                       content: event.content!,
                       timestamp: new Date(),
+                      traceItems,
                     },
                   ],
                 };
@@ -270,6 +325,87 @@ export function GeminiChat() {
               };
             })
           );
+
+        } else if (event.type === "status") {
+          const item: TraceItem = {
+            id: `status-${event.ts ?? Date.now()}-${Math.random().toString(36).slice(2, 6)}`,
+            type: "status",
+            title: event.stage ?? "处理中",
+            message: event.message,
+            itemStatus: "info",
+            startTs: event.ts ?? Date.now(),
+          };
+          // Ensure assistant message placeholder exists before appending trace
+          setConversations((prev) =>
+            prev.map((c) => {
+              if (c.id !== streamConvId) return c;
+              const exists = c.messages.some((m) => m.id === aiMsgId);
+              if (!exists) {
+                return {
+                  ...c,
+                  messages: [
+                    ...c.messages,
+                    { id: aiMsgId, role: "assistant" as const, content: "", timestamp: new Date(), traceItems: [item] },
+                  ],
+                };
+              }
+              return {
+                ...c,
+                messages: c.messages.map((m) =>
+                  m.id === aiMsgId ? { ...m, traceItems: [...(m.traceItems ?? []), item] } : m
+                ),
+              };
+            })
+          );
+
+        } else if (event.type === "tool_start" && event.tool) {
+          const item: TraceItem = {
+            id: `${event.tool}-${event.ts ?? Date.now()}`,
+            type: "tool_start",
+            tool: event.tool,
+            title: event.title ?? event.tool,
+            inputSummary: event.input_summary,
+            itemStatus: "running",
+            startTs: event.ts ?? Date.now(),
+          };
+          // Ensure assistant message placeholder exists
+          setConversations((prev) =>
+            prev.map((c) => {
+              if (c.id !== streamConvId) return c;
+              const exists = c.messages.some((m) => m.id === aiMsgId);
+              if (!exists) {
+                return {
+                  ...c,
+                  messages: [
+                    ...c.messages,
+                    { id: aiMsgId, role: "assistant" as const, content: "", timestamp: new Date(), traceItems: [item] },
+                  ],
+                };
+              }
+              return {
+                ...c,
+                messages: c.messages.map((m) =>
+                  m.id === aiMsgId ? { ...m, traceItems: [...(m.traceItems ?? []), item] } : m
+                ),
+              };
+            })
+          );
+
+        } else if (event.type === "tool_end" && event.tool) {
+          updateTraceItem(streamConvId, aiMsgId, event.tool, {
+            type: "tool_end",
+            outputSummary: event.output_summary,
+            itemStatus: "success",
+            durationMs: event.duration_ms,
+          }, setConversations);
+
+        } else if (event.type === "tool_error" && event.tool) {
+          updateTraceItem(streamConvId, aiMsgId, event.tool, {
+            type: "tool_error",
+            errorSummary: event.error_summary,
+            itemStatus: "error",
+            durationMs: event.duration_ms,
+          }, setConversations);
         }
       },
       () => {
@@ -308,7 +444,7 @@ export function GeminiChat() {
           return {
             ...c,
             messages: c.messages.map((m) =>
-              m.id === msgId ? { ...m, content: "", id: newAiMsgId } : m
+              m.id === msgId ? { ...m, content: "", id: newAiMsgId, traceItems: [] } : m
             ),
           };
         })
@@ -336,6 +472,41 @@ export function GeminiChat() {
                 };
               })
             );
+          } else if (event.type === "status") {
+            const item: TraceItem = {
+              id: `status-${event.ts ?? Date.now()}-${Math.random().toString(36).slice(2, 6)}`,
+              type: "status",
+              title: event.stage ?? "处理中",
+              message: event.message,
+              itemStatus: "info",
+              startTs: event.ts ?? Date.now(),
+            };
+            appendTraceItem(regenConvId, newAiMsgId, item, setConversations);
+          } else if (event.type === "tool_start" && event.tool) {
+            const item: TraceItem = {
+              id: `${event.tool}-${event.ts ?? Date.now()}`,
+              type: "tool_start",
+              tool: event.tool,
+              title: event.title ?? event.tool,
+              inputSummary: event.input_summary,
+              itemStatus: "running",
+              startTs: event.ts ?? Date.now(),
+            };
+            appendTraceItem(regenConvId, newAiMsgId, item, setConversations);
+          } else if (event.type === "tool_end" && event.tool) {
+            updateTraceItem(regenConvId, newAiMsgId, event.tool, {
+              type: "tool_end",
+              outputSummary: event.output_summary,
+              itemStatus: "success",
+              durationMs: event.duration_ms,
+            }, setConversations);
+          } else if (event.type === "tool_error" && event.tool) {
+            updateTraceItem(regenConvId, newAiMsgId, event.tool, {
+              type: "tool_error",
+              errorSummary: event.error_summary,
+              itemStatus: "error",
+              durationMs: event.duration_ms,
+            }, setConversations);
           }
         },
         () => {
@@ -402,6 +573,7 @@ export function GeminiChat() {
                   <GeminiMessage
                     key={msg.id}
                     message={msg}
+                    model={selectedModel}
                     onRegenerate={msg.role === "assistant" ? handleRegenerate : undefined}
                   />
                 );
diff --git a/frontend/components/gemini/GeminiMessage.tsx b/frontend/components/gemini/GeminiMessage.tsx
index c08e051..07de223 100644
--- a/frontend/components/gemini/GeminiMessage.tsx
+++ b/frontend/components/gemini/GeminiMessage.tsx
@@ -3,7 +3,8 @@
 import { useState } from "react";
 import { ThumbsUp, ThumbsDown, Copy, RefreshCw, Check, Paperclip, Download } from "lucide-react";
 import { cn } from "@/lib/utils";
-import { getAttachmentDownloadUrl, type AttachmentData } from "@/lib/api";
+import { getAttachmentDownloadUrl, type AttachmentData, type TraceItem } from "@/lib/api";
+import { TracePanel } from "./TracePanel";
 
 export interface Message {
   id: string;
@@ -11,10 +12,12 @@ export interface Message {
   content: string;
   timestamp?: Date;
   attachments?: AttachmentData[];
+  traceItems?: TraceItem[];
 }
 
 interface GeminiMessageProps {
   message: Message;
+  model?: "flash" | "auto" | "pro";
   onRegenerate?: (id: string) => void;
 }
 
@@ -165,7 +168,7 @@ const GemIcon = ({ size = 18 }: { size?: number }) => (
   </svg>
 );
 
-export function GeminiMessage({ message, onRegenerate }: GeminiMessageProps) {
+export function GeminiMessage({ message, model = "auto", onRegenerate }: GeminiMessageProps) {
   const [copied, setCopied] = useState(false);
   const [feedback, setFeedback] = useState<"up" | "down" | null>(null);
 
@@ -195,6 +198,13 @@ export function GeminiMessage({ message, onRegenerate }: GeminiMessageProps) {
         <GemIcon />
         {/* Content */}
         <div className="flex-1 min-w-0">
+          {message.traceItems && message.traceItems.length > 0 && (
+            <TracePanel
+              items={message.traceItems}
+              model={model}
+              className="mb-3"
+            />
+          )}
           <div className="space-y-0.5">{renderContent(message.content)}</div>
 
           {/* Attachments */}
diff --git a/frontend/components/gemini/TracePanel.tsx b/frontend/components/gemini/TracePanel.tsx
new file mode 100644
index 0000000..f9deb04
--- /dev/null
+++ b/frontend/components/gemini/TracePanel.tsx
@@ -0,0 +1,192 @@
+"use client";
+
+import { useState } from "react";
+import {
+  CheckCircle2,
+  XCircle,
+  ChevronDown,
+  ChevronRight,
+  Loader2,
+  Zap,
+  Brain,
+} from "lucide-react";
+import { cn } from "@/lib/utils";
+import {
+  Collapsible,
+  CollapsibleContent,
+  CollapsibleTrigger,
+} from "@/components/ui/collapsible";
+import type { TraceItem } from "@/lib/api";
+
+const TOOL_ICONS: Record<string, string> = {
+  kb_search: "🗂️",
+  web_search: "🌐",
+  ticket_list: "🎫",
+  ticket_detail: "🎫",
+  generate_document: "📄",
+  sandbox_run: "⚙️",
+};
+
+function StatusIcon({ status }: { status: TraceItem["itemStatus"] }) {
+  switch (status) {
+    case "running":
+      return (
+        <Loader2
+          size={13}
+          className="animate-spin text-[var(--gem-accent,#4285f4)] shrink-0"
+        />
+      );
+    case "success":
+      return (
+        <CheckCircle2 size={13} className="text-emerald-400 shrink-0" />
+      );
+    case "error":
+      return <XCircle size={13} className="text-red-400 shrink-0" />;
+    case "info":
+      return (
+        <Brain
+          size={13}
+          className="text-[var(--gem-text-muted)] shrink-0"
+        />
+      );
+  }
+}
+
+function formatDuration(ms?: number): string {
+  if (!ms) return "";
+  if (ms < 1000) return `${ms}ms`;
+  return `${(ms / 1000).toFixed(1)}s`;
+}
+
+function TraceItemRow({
+  item,
+  showDetails,
+}: {
+  item: TraceItem;
+  showDetails: boolean;
+}) {
+  const icon = item.tool ? (TOOL_ICONS[item.tool] ?? "🔧") : null;
+
+  return (
+    <div
+      className={cn(
+        "flex items-start gap-2 py-1.5 px-2 rounded-lg text-xs transition-colors",
+        item.itemStatus === "running" && "bg-[var(--gem-surface-2)]"
+      )}
+    >
+      <div className="mt-0.5">
+        <StatusIcon status={item.itemStatus} />
+      </div>
+
+      <div className="flex-1 min-w-0">
+        <div className="flex items-center gap-1.5">
+          {icon && <span>{icon}</span>}
+          <span
+            className={cn(
+              "font-medium",
+              item.itemStatus === "error"
+                ? "text-red-400"
+                : "text-[var(--gem-text)]"
+            )}
+          >
+            {item.title}
+          </span>
+          {item.durationMs !== undefined && (
+            <span className="text-[var(--gem-text-muted)] ml-auto shrink-0">
+              {formatDuration(item.durationMs)}
+            </span>
+          )}
+        </div>
+
+        {showDetails && (
+          <div className="mt-0.5 space-y-0.5">
+            {item.inputSummary && (
+              <p className="text-[var(--gem-text-muted)] truncate">
+                {item.inputSummary}
+              </p>
+            )}
+            {item.outputSummary && (
+              <p className="text-[var(--gem-text-secondary)] truncate">
+                {item.outputSummary}
+              </p>
+            )}
+            {item.errorSummary && (
+              <p className="text-red-400 truncate">{item.errorSummary}</p>
+            )}
+            {item.message && item.type === "status" && (
+              <p className="text-[var(--gem-text-muted)]">{item.message}</p>
+            )}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+interface TracePanelProps {
+  items: TraceItem[];
+  model: "flash" | "auto" | "pro";
+  className?: string;
+}
+
+export function TracePanel({ items, model, className }: TracePanelProps) {
+  const isPro = model === "pro";
+  const [open, setOpen] = useState(isPro);
+
+  const hasRunning = items.some((i) => i.itemStatus === "running");
+
+  const summaryText = (() => {
+    const running = items.filter((i) => i.itemStatus === "running");
+    if (running.length > 0) {
+      return `正在 ${running[running.length - 1].title}...`;
+    }
+    const errors = items.filter((i) => i.type === "tool_error");
+    const tools = items.filter((i) => i.type === "tool_end");
+    if (errors.length > 0) {
+      return `已完成（${errors.length} 个工具调用失败）`;
+    }
+    if (tools.length > 0) {
+      const names = tools.map((t) => t.title).join("、");
+      return `已完成：${names}`;
+    }
+    return "正在分析...";
+  })();
+
+  return (
+    <Collapsible open={open} onOpenChange={setOpen} className={cn("w-full", className)}>
+      <CollapsibleTrigger asChild>
+        <button
+          className={cn(
+            "flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-xs",
+            "text-[var(--gem-text-muted)] hover:text-[var(--gem-text)]",
+            "hover:bg-[var(--gem-surface-2)] transition-colors cursor-pointer"
+          )}
+        >
+          <Zap
+            size={12}
+            className={cn(
+              "shrink-0",
+              hasRunning
+                ? "text-[var(--gem-accent,#4285f4)] animate-pulse"
+                : "text-[var(--gem-text-muted)]"
+            )}
+          />
+          <span className="flex-1 text-left truncate">{summaryText}</span>
+          {open ? (
+            <ChevronDown size={12} className="shrink-0" />
+          ) : (
+            <ChevronRight size={12} className="shrink-0" />
+          )}
+        </button>
+      </CollapsibleTrigger>
+
+      <CollapsibleContent>
+        <div className="mt-1 ml-2 border-l border-[var(--gem-border)] pl-3 space-y-0.5">
+          {items.map((item) => (
+            <TraceItemRow key={item.id} item={item} showDetails={isPro} />
+          ))}
+        </div>
+      </CollapsibleContent>
+    </Collapsible>
+  );
+}
diff --git a/frontend/lib/api.ts b/frontend/lib/api.ts
index f6addda..0b530e4 100644
--- a/frontend/lib/api.ts
+++ b/frontend/lib/api.ts
@@ -112,9 +112,35 @@ export function getAttachmentDownloadUrl(attachmentId: string): string {
 // ── SSE Chat Stream ──────────────────────────────────────────────────────────
 
 export interface ChatStreamEvent {
-  type: "token" | "tool_start" | "tool_end" | "done";
+  type: "token" | "status" | "tool_start" | "tool_end" | "tool_error" | "done" | "error";
+  // token
   content?: string;
+  // status
+  stage?: string;
+  message?: string;
+  // tool_start / tool_end / tool_error
   tool?: string;
+  title?: string;
+  input_summary?: string;
+  output_summary?: string;
+  error_summary?: string;
+  status?: "success" | "error";
+  duration_ms?: number;
+  ts?: number;
+}
+
+export interface TraceItem {
+  id: string;
+  type: "status" | "tool_start" | "tool_end" | "tool_error";
+  tool?: string;
+  title: string;
+  message?: string;
+  inputSummary?: string;
+  outputSummary?: string;
+  errorSummary?: string;
+  itemStatus: "running" | "success" | "error" | "info";
+  durationMs?: number;
+  startTs: number;
 }
 
 export function streamChat(