diff --git a/components/canvas/chat-panel/canvas-chat-media.ts b/components/canvas/chat-panel/canvas-chat-media.ts
index 0d022f2d6..88d2e2269 100644
--- a/components/canvas/chat-panel/canvas-chat-media.ts
+++ b/components/canvas/chat-panel/canvas-chat-media.ts
@@ -381,11 +381,15 @@ export function sortCanvasMessagesByCreatedAt(messages: ChatMessage[]): ChatMess
     .sort((a, b) => {
       const messageA = a.message;
       const messageB = b.message;
-      const timeA = getMessageTimestamp(messageA) ?? 0;
-      const timeB = getMessageTimestamp(messageB) ?? 0;
-      if (timeA !== timeB) return timeA - timeB;
+      const timeA = getMessageTimestamp(messageA);
+      const timeB = getMessageTimestamp(messageB);
+      const hasTimeA = timeA !== null;
+      const hasTimeB = timeB !== null;
 
-      if (messageA.role !== messageB.role) {
+      if (hasTimeA && hasTimeB && timeA !== timeB) return timeA - timeB;
+      if (hasTimeA !== hasTimeB) return hasTimeA ? -1 : 1;
+
+      if (hasTimeA && hasTimeB && messageA.role !== messageB.role) {
         if (messageA.role === "user") return -1;
         if (messageB.role === "user") return 1;
       }
diff --git a/tests/routes/canvas-chat-helpers.test.ts b/tests/routes/canvas-chat-helpers.test.ts
index d51b0caec..6edd96b14 100644
--- a/tests/routes/canvas-chat-helpers.test.ts
+++ b/tests/routes/canvas-chat-helpers.test.ts
@@ -4,6 +4,7 @@ import {
   extractAssistantImageUrls,
   extractVideoUrls,
   normalizeMediaUrl,
+  sortCanvasMessagesByCreatedAt,
   stripMediaMarkup,
 } from "@/components/canvas/chat-panel/canvas-chat-media";
 import {
@@ -211,6 +212,54 @@ import type { CanvasAgentContext } from "@/types/canvas/agent-protocol";
 import type { ChatMessage } from "@/lib/types";
 
 test.describe("canvas chat pure helpers", () => {
+  test("keeps optimistic messages without timestamps after persisted history", () => {
+    const messages = [
+      {
+        id: "optimistic-latest-user",
+        role: "user",
+        parts: [{ type: "text", text: "你能为我做什么？列出表给我" }],
+      },
+      {
+        id: "persisted-first-user",
+        role: "user",
+        createdAt: "2026-07-07T01:00:00.000Z",
+        parts: [{ type: "text", text: "你好" }],
+      },
+      {
+        id: "persisted-first-assistant",
+        role: "assistant",
+        createdAt: "2026-07-07T01:00:01.000Z",
+        parts: [{ type: "text", text: "你好，我在。" }],
+      },
+    ] as ChatMessage[];
+
+    expect(sortCanvasMessagesByCreatedAt(messages).map((message) => message.id)).toEqual([
+      "persisted-first-user",
+      "persisted-first-assistant",
+      "optimistic-latest-user",
+    ]);
+  });
+
+  test("preserves relative order among messages without timestamps", () => {
+    const messages = [
+      {
+        id: "pending-user",
+        role: "user",
+        parts: [{ type: "text", text: "生成一张图" }],
+      },
+      {
+        id: "pending-assistant",
+        role: "assistant",
+        parts: [{ type: "text", text: "分析中" }],
+      },
+    ] as ChatMessage[];
+
+    expect(sortCanvasMessagesByCreatedAt(messages).map((message) => message.id)).toEqual([
+      "pending-user",
+      "pending-assistant",
+    ]);
+  });
+
   test("formats uploaded spreadsheet rows as safe markdown tables for OpenClaw", () => {
     const markdown = rowsToOpenClawMarkdownTable([
       ["名称", "备注"],