diff --git a/components/canvas/CanvasChatPanel.tsx b/components/canvas/CanvasChatPanel.tsx
index a3b489d51..3120eb0d8 100644
--- a/components/canvas/CanvasChatPanel.tsx
+++ b/components/canvas/CanvasChatPanel.tsx
@@ -4,6 +4,7 @@ import { useChat } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
 import { shouldUseCanvasAgentRuntime } from "@/lib/ai/canvas-agent-runtime/routing";
 import { CanvasAgentProgressMessage } from "@/components/canvas/chat-panel/canvas-agent-progress";
+import { canvasHistoryForChat } from "@/lib/client/canvas-history-response";
 import { useCanvasAgentRun } from "@/components/canvas/chat-panel/use-canvas-agent-run";
 import { canvasAgentProgress, type CanvasAgentProgress } from "@/lib/ai/canvas-agent-runtime/progress";
 import { useEffect, useRef, useState, useCallback, useMemo, lazy, Suspense, type ClipboardEvent as ReactClipboardEvent, type ComponentProps, type MouseEvent as ReactMouseEvent, type PointerEvent as ReactPointerEvent } from "react";
@@ -4515,8 +4516,7 @@ export function CanvasChatPanel({
         dedupingInterval: 10000,
       }
     );
-  const historyData =
-    fetchedHistoryData?.chatId === rawChatId ? fetchedHistoryData : undefined;
+  const historyData = canvasHistoryForChat(fetchedHistoryData, rawChatId);
   const initialCanvasMessageCount =
     activeChatId === chatId ? initialMessages.length : 0;
   const voteSWRKey =
diff --git a/lib/client/canvas-history-response.ts b/lib/client/canvas-history-response.ts
new file mode 100644
index 000000000..f46a0352c
--- /dev/null
+++ b/lib/client/canvas-history-response.ts
@@ -0,0 +1,9 @@
+/** Accept an exact-key SWR payload from older consumers without weakening tagged chat isolation. */
+export function canvasHistoryForChat<T>(
+  payload: { chatId?: string; messages: T[] } | undefined,
+  chatId: string,
+): { messages: T[] } | undefined {
+  if (!payload || !chatId || !Array.isArray(payload.messages)) return undefined;
+  if (payload.chatId !== undefined && payload.chatId !== chatId) return undefined;
+  return payload;
+}
diff --git a/tests/routes/canvas-agent-runtime-progress.test.tsx b/tests/routes/canvas-agent-runtime-progress.test.tsx
index dc79d291b..90c6ea86e 100644
--- a/tests/routes/canvas-agent-runtime-progress.test.tsx
+++ b/tests/routes/canvas-agent-runtime-progress.test.tsx
@@ -1,4 +1,5 @@
 import { createCanvasSaveQueue } from "@/lib/client/canvas-save-queue";
+import { canvasHistoryForChat } from "@/lib/client/canvas-history-response";
 import { expect, test } from "@playwright/test";
 import { createElement } from "react";
 import { renderToStaticMarkup } from "react-dom/server";
@@ -12,6 +13,13 @@ function fixture(): AgentRunView {
   updatedAt: new Date().toISOString(), cancelRequested: false, resumable: false,
   activities: [{ id: "step-1", title: "生成图片", status: "started" }] };
 }
+test("history accepts existing exact-key payloads and rejects another tagged chat", () => {
+ const messages = [{ id: "assistant-1", parts: [{ type: "text", text: "completed" }] }];
+ expect(canvasHistoryForChat({ messages }, "chat-1")?.messages).toBe(messages);
+ expect(canvasHistoryForChat({ chatId: "chat-1", messages }, "chat-1")?.messages).toBe(messages);
+ expect(canvasHistoryForChat({ chatId: "chat-2", messages }, "chat-1")).toBeUndefined();
+ expect(canvasHistoryForChat({ messages }, "")).toBeUndefined();
+});
 test("public status converts legacy engine and isolation messages without exposing diagnostics", () => {
  for (const text of ["ZCode 正在规划并执行画布任务", "正在启动 ZCode 独立沙箱", "sandbox bwrap failed at /var/lib/agent"])
   expect(canvasAgentProgressLabel(text)).not.toMatch(/zcode|沙箱|sandbox|bwrap|\/var\//i);