diff --git a/bun.lock b/bun.lock
index 45b159c..4f617f5 100644
--- a/bun.lock
+++ b/bun.lock
@@ -19,6 +19,8 @@
         "antd": "^6.4.3",
         "drizzle-orm": "^0.45.2",
         "es-toolkit": "^1.47.0",
+        "overlayscrollbars": "^2.16.0",
+        "overlayscrollbars-react": "^0.5.6",
         "pino": "^10.3.1",
         "pino-pretty": "^13.1.3",
         "pino-roll": "^4.0.0",
@@ -1259,6 +1261,10 @@
 
     "optionator": ["optionator@0.9.4", "https://registry.npmmirror.com/optionator/-/optionator-0.9.4.tgz", { "dependencies": { "deep-is": "^0.1.3", "fast-levenshtein": "^2.0.6", "levn": "^0.4.1", "prelude-ls": "^1.2.1", "type-check": "^0.4.0", "word-wrap": "^1.2.5" } }, "sha512-6IpQ7mKUxRcZNLIObR0hz7lxsapSSIYNZJwXPGeF0mTVqGKFIXj1DQcMoT22S3ROcLyY/rz0PWaWZ9ayWmad9g=="],
 
+    "overlayscrollbars": ["overlayscrollbars@2.16.0", "", {}, "sha512-N03oje/q7j93D0aLZtoCdsDSYLmhheSsv8H7oSLE7HhdV9P/bmCURtLV/KbPye7P/bpfyt/obSfDpGUYoJ0OWg=="],
+
+    "overlayscrollbars-react": ["overlayscrollbars-react@0.5.6", "", { "peerDependencies": { "overlayscrollbars": "^2.0.0", "react": ">=16.8.0" } }, "sha512-E5To04bL5brn9GVCZ36SnfGanxa2I2MDkWoa4Cjo5wol7l+diAgi4DBc983V7l2nOk/OLJ6Feg4kySspQEGDBw=="],
+
     "own-keys": ["own-keys@1.0.1", "https://registry.npmmirror.com/own-keys/-/own-keys-1.0.1.tgz", { "dependencies": { "get-intrinsic": "^1.2.6", "object-keys": "^1.1.1", "safe-push-apply": "^1.0.0" } }, "sha512-qFOyK5PjiWZd+QQIh+1jhdb9LpxTF0qs7Pm8o5QHYZ0M3vKqSqzsZaEB6oWlxZ+q2sJBMI/Ktgd2N5ZwQoRHfg=="],
 
     "p-limit": ["p-limit@3.1.0", "https://registry.npmmirror.com/p-limit/-/p-limit-3.1.0.tgz", { "dependencies": { "yocto-queue": "^0.1.0" } }, "sha512-TYOanM3wGwNGsZN2cVTYPArw454xnXj5qmWF1bEoAc4+cU/ol7GVh7odevjp1FNHduHc3KZMcFduxU5Xc6uJRQ=="],
diff --git a/package.json b/package.json
index 4e1d231..385aee4 100644
--- a/package.json
+++ b/package.json
@@ -67,6 +67,8 @@
     "antd": "^6.4.3",
     "drizzle-orm": "^0.45.2",
     "es-toolkit": "^1.47.0",
+    "overlayscrollbars": "^2.16.0",
+    "overlayscrollbars-react": "^0.5.6",
     "pino": "^10.3.1",
     "pino-pretty": "^13.1.3",
     "pino-roll": "^4.0.0",
diff --git a/src/web/consoles/workbench/components/chat/ChatPanel.tsx b/src/web/consoles/workbench/components/chat/ChatPanel.tsx
index bdba0f5..79a4ee7 100644
--- a/src/web/consoles/workbench/components/chat/ChatPanel.tsx
+++ b/src/web/consoles/workbench/components/chat/ChatPanel.tsx
@@ -1,5 +1,5 @@
 import { useChat } from "@ai-sdk/react";
-import { ArrowDownOutlined, CopyOutlined, EditOutlined, RedoOutlined, RobotOutlined } from "@ant-design/icons";
+import { CopyOutlined, EditOutlined, RedoOutlined, RobotOutlined } from "@ant-design/icons";
 import { Sender } from "@ant-design/x";
 import { useQueryClient } from "@tanstack/react-query";
 import { DefaultChatTransport, type UIMessage } from "ai";
@@ -14,10 +14,10 @@ import {
 } from "../../../../hooks/use-conversations";
 import { useLogger } from "../../../../hooks/use-logger";
 import { useModelList } from "../../../../hooks/use-models";
+import { ChatScrollArea } from "./ChatScrollArea";
 import { ReasoningPart } from "./parts/ReasoningPart";
 import { TextPart } from "./parts/TextPart";
 import { ToolPart } from "./parts/ToolPart";
-import { useChatScroll } from "./use-chat-scroll";
 
 interface ChatPanelProps {
   conversationId: null | string;
@@ -35,7 +35,6 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
   const [loadingHistory, setLoadingHistory] = useState(false);
   const [selectedModelId, setSelectedModelId] = useState<null | string>(null);
   const fetchRef = useRef(fetchMessages);
-  const scrollRef = useRef<HTMLDivElement>(null);
   const skipHistoryLoadRef = useRef<null | string>(null);
 
   const { data: modelsData } = useModelList({ pageSize: 200 });
@@ -56,8 +55,6 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
 
   const isLoading = status === "submitted" || status === "streaming";
 
-  const { isAtBottom, scrollToBottom } = useChatScroll({ messages, scrollRef, status });
-
   useEffect(() => {
     if (!conversationId) {
       setMessages([]);
@@ -348,7 +345,7 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
           <Spin />
         </div>
       ) : (
-        <div className="chat-scroll-area" ref={scrollRef}>
+        <ChatScrollArea messages={messages} status={status}>
           <Flex gap={8} vertical>
             {messages.map((msg, idx) => (
               <Card
@@ -394,16 +391,7 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
               </Flex>
             )}
           </Flex>
-        </div>
-      )}
-      {!isAtBottom && (
-        <Button
-          className="chat-scroll-bottom-btn"
-          icon={<ArrowDownOutlined />}
-          onClick={scrollToBottom}
-          shape="circle"
-          size="small"
-        />
+        </ChatScrollArea>
       )}
       <div className="chat-sender-area">
         <Sender
diff --git a/src/web/consoles/workbench/components/chat/ChatScrollArea.tsx b/src/web/consoles/workbench/components/chat/ChatScrollArea.tsx
new file mode 100644
index 0000000..ce1c357
--- /dev/null
+++ b/src/web/consoles/workbench/components/chat/ChatScrollArea.tsx
@@ -0,0 +1,58 @@
+import type { UIMessage } from "ai";
+
+import { ArrowDownOutlined } from "@ant-design/icons";
+import { Button } from "antd";
+import "overlayscrollbars/styles/overlayscrollbars.css";
+import { OverlayScrollbarsComponent, type OverlayScrollbarsComponentRef } from "overlayscrollbars-react";
+import { useCallback, useRef, useState } from "react";
+
+import { useChatScroll } from "./use-chat-scroll";
+
+interface ChatScrollAreaProps {
+  children: React.ReactNode;
+  messages: UIMessage[];
+  status: string;
+}
+
+export function ChatScrollArea({ children, messages, status }: ChatScrollAreaProps) {
+  const scrollRef = useRef<HTMLDivElement>(null);
+  const osRef = useRef<OverlayScrollbarsComponentRef>(null);
+  const [viewportElement, setViewportElement] = useState<HTMLDivElement | null>(null);
+
+  const handleOsInitialized = useCallback(() => {
+    const os = osRef.current;
+    if (!os) return;
+    const instance = os.osInstance();
+    if (!instance) return;
+    const viewport = instance.elements().viewport as HTMLDivElement;
+    scrollRef.current = viewport;
+    setViewportElement(viewport);
+  }, []);
+
+  const { isAtBottom, scrollToBottom } = useChatScroll({ messages, scrollRef, status, viewportElement });
+
+  return (
+    <>
+      <OverlayScrollbarsComponent
+        className="chat-scroll-area"
+        events={{ initialized: handleOsInitialized }}
+        options={{
+          overflow: { x: "hidden", y: "scroll" },
+          scrollbars: { autoHide: "move", theme: "os-theme-custom" },
+        }}
+        ref={osRef}
+      >
+        {children}
+      </OverlayScrollbarsComponent>
+      {!isAtBottom && (
+        <Button
+          className="chat-scroll-bottom-btn"
+          icon={<ArrowDownOutlined />}
+          onClick={scrollToBottom}
+          shape="circle"
+          size="small"
+        />
+      )}
+    </>
+  );
+}
diff --git a/src/web/consoles/workbench/components/chat/parts/CodeBlockWithCopy.tsx b/src/web/consoles/workbench/components/chat/parts/CodeBlockWithCopy.tsx
new file mode 100644
index 0000000..8875950
--- /dev/null
+++ b/src/web/consoles/workbench/components/chat/parts/CodeBlockWithCopy.tsx
@@ -0,0 +1,57 @@
+import { CopyOutlined } from "@ant-design/icons";
+import { CodeHighlighter } from "@ant-design/x";
+import { App, Button, Flex, Typography } from "antd";
+import React from "react";
+
+interface CodeBlockWithCopyProps {
+  block?: boolean;
+  children?: React.ReactNode;
+  className?: string;
+  lang?: string;
+  streamStatus?: "done" | "loading";
+}
+
+export function CodeBlockWithCopy({ block, children, className, lang }: CodeBlockWithCopyProps) {
+  const { message } = App.useApp();
+
+  if (!block) {
+    return <code className={className}>{children}</code>;
+  }
+
+  const codeText = extractText(children);
+  // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
+  const displayLang = lang || "plaintext";
+
+  const handleCopy = () => {
+    void navigator.clipboard.writeText(codeText).then(() => {
+      void message.success("已复制");
+    });
+  };
+
+  const header = (
+    <Flex align="center" justify="space-between" style={{ padding: "0 4px" }}>
+      <Typography.Text style={{ color: "var(--ant-color-text-quaternary)", fontSize: 12 }}>
+        {displayLang}
+      </Typography.Text>
+      <Button
+        icon={<CopyOutlined />}
+        onClick={handleCopy}
+        size="small"
+        style={{ color: "var(--ant-color-text-quaternary)" }}
+        type="text"
+      />
+    </Flex>
+  );
+
+  return (
+    <CodeHighlighter header={header} lang={displayLang}>
+      {codeText}
+    </CodeHighlighter>
+  );
+}
+
+function extractText(children: React.ReactNode): string {
+  return React.Children.toArray(children)
+    .map((child) => (typeof child === "string" ? child : ""))
+    .join("");
+}
diff --git a/src/web/consoles/workbench/components/chat/parts/TextPart.tsx b/src/web/consoles/workbench/components/chat/parts/TextPart.tsx
index cea4f19..32541db 100644
--- a/src/web/consoles/workbench/components/chat/parts/TextPart.tsx
+++ b/src/web/consoles/workbench/components/chat/parts/TextPart.tsx
@@ -1,13 +1,21 @@
 import { XMarkdown } from "@ant-design/x-markdown";
+import "@ant-design/x-markdown/themes/light.css";
 import { Typography } from "antd";
 
 import type { PartProps } from "./types";
 
+import { CodeBlockWithCopy } from "./CodeBlockWithCopy";
+
 interface TextPartProps extends PartProps {
   isStreaming: boolean;
   role: string;
 }
 
+const xmarkdownComponents = {
+  code: CodeBlockWithCopy,
+  pre: ({ children }: { children?: React.ReactNode }) => <>{children}</>,
+};
+
 export function TextPart({ isStreaming, part, role }: TextPartProps) {
   const text = typeof part["text"] === "string" ? part["text"] : "";
 
@@ -16,7 +24,12 @@ export function TextPart({ isStreaming, part, role }: TextPartProps) {
       {role === "user" ? (
         <Typography.Paragraph className="message-body-text">{text}</Typography.Paragraph>
       ) : (
-        <XMarkdown content={text} streaming={{ hasNextChunk: isStreaming }} />
+        <XMarkdown
+          className="x-markdown-light"
+          components={xmarkdownComponents}
+          content={text}
+          streaming={{ hasNextChunk: isStreaming }}
+        />
       )}
     </div>
   );
diff --git a/src/web/consoles/workbench/components/chat/use-chat-scroll.ts b/src/web/consoles/workbench/components/chat/use-chat-scroll.ts
index 570a6ce..b7c2672 100644
--- a/src/web/consoles/workbench/components/chat/use-chat-scroll.ts
+++ b/src/web/consoles/workbench/components/chat/use-chat-scroll.ts
@@ -1,18 +1,21 @@
 import type { UIMessage } from "ai";
 
-import { useCallback, useEffect, useState } from "react";
+import { useCallback, useEffect, useRef, useState } from "react";
 
 const NEAR_BOTTOM_THRESHOLD = 80;
 
 interface UseChatScrollOptions {
+  loadingHistory?: boolean;
   messages: UIMessage[];
   scrollRef: React.RefObject<HTMLDivElement | null>;
   status: string;
+  viewportElement: HTMLDivElement | null;
 }
 
-export function useChatScroll({ messages, scrollRef, status }: UseChatScrollOptions) {
+export function useChatScroll({ loadingHistory, messages, scrollRef, status, viewportElement }: UseChatScrollOptions) {
   const [isAtBottom, setIsAtBottom] = useState(true);
   const isStreaming = status === "streaming";
+  const prevLoadingRef = useRef(loadingHistory ?? false);
 
   const checkNearBottom = useCallback(() => {
     const el = scrollRef.current;
@@ -21,33 +24,45 @@ export function useChatScroll({ messages, scrollRef, status }: UseChatScrollOpti
   }, [scrollRef]);
 
   useEffect(() => {
-    const el = scrollRef.current;
+    const el = viewportElement;
     if (!el) return;
 
-    setIsAtBottom(checkNearBottom());
-
     const handleScroll = () => {
       setIsAtBottom(checkNearBottom());
     };
 
     el.addEventListener("scroll", handleScroll, { passive: true });
     return () => el.removeEventListener("scroll", handleScroll);
-  }, [scrollRef, checkNearBottom]);
+  }, [viewportElement, checkNearBottom]);
+
+  useEffect(() => {
+    const wasLoading = prevLoadingRef.current;
+    prevLoadingRef.current = loadingHistory ?? false;
+
+    if (wasLoading && !loadingHistory) {
+      const el = scrollRef.current;
+      if (!el) return;
+      requestAnimationFrame(() => {
+        const target = scrollRef.current;
+        if (!target) return;
+        target.scrollTo({ behavior: "instant", top: target.scrollHeight });
+        setIsAtBottom(true);
+      });
+      return;
+    }
+  }, [loadingHistory, scrollRef]);
 
   useEffect(() => {
     const el = scrollRef.current;
     if (!el || !isAtBottom) return;
 
-    el.scrollTo({
-      behavior: isStreaming ? "instant" : "smooth",
-      top: el.scrollHeight,
-    });
+    el.scrollTo({ behavior: "instant", top: el.scrollHeight });
   }, [messages, isStreaming, isAtBottom, scrollRef]);
 
   const scrollToBottom = useCallback(() => {
     const el = scrollRef.current;
     if (!el) return;
-    el.scrollTo({ behavior: "smooth", top: el.scrollHeight });
+    el.scrollTo({ behavior: "instant", top: el.scrollHeight });
     setIsAtBottom(true);
   }, [scrollRef]);
 
diff --git a/src/web/styles.css b/src/web/styles.css
index c6c2fe0..a4e3d1a 100644
--- a/src/web/styles.css
+++ b/src/web/styles.css
@@ -124,22 +124,13 @@ body {
   margin-top: 8px;
 }
 
-.message-body pre {
-  background: var(--ant-color-bg-layout);
-  padding: 8px 12px;
-  border-radius: 6px;
-  overflow-x: auto;
-  font-size: 13px;
-}
-
 .chat-scroll-area {
   flex: 1;
   min-height: 0;
-  overflow: auto;
   overflow-anchor: auto;
   margin-left: var(--ant-padding-sm);
   border-radius: var(--ant-border-radius-lg);
-  scroll-behavior: smooth;
+  height: 100%;
 }
 
 .chat-loading-indicator {
@@ -219,3 +210,38 @@ body {
 .app-page-flex {
   flex: 1;
 }
+
+.os-theme-custom {
+  --os-size: 8px;
+  --os-padding-perpendicular: 2px;
+  --os-padding-axis: 2px;
+  --os-track-border-radius: 10px;
+  --os-handle-border-radius: 10px;
+  --os-handle-bg: rgba(0, 0, 0, 0.15);
+  --os-handle-bg-hover: rgba(0, 0, 0, 0.25);
+  --os-handle-bg-active: rgba(0, 0, 0, 0.35);
+  --os-handle-min-size: 33px;
+  --os-handle-max-size: none;
+  --os-handle-interactive-area-offset: 4px;
+}
+
+.x-markdown-light table {
+  border-collapse: collapse;
+  width: 100%;
+}
+
+.x-markdown-light th,
+.x-markdown-light td {
+  border: 1px solid var(--ant-color-border);
+  padding: 6px 12px;
+  text-align: left;
+}
+
+.x-markdown-light th {
+  background: var(--ant-color-fill-quaternary);
+  font-weight: 600;
+}
+
+.x-markdown-light .x-md-table-wrap {
+  overflow-x: auto;
+}
diff --git a/tests/web/components/chat/CodeBlockWithCopy.test.tsx b/tests/web/components/chat/CodeBlockWithCopy.test.tsx
new file mode 100644
index 0000000..073a16c
--- /dev/null
+++ b/tests/web/components/chat/CodeBlockWithCopy.test.tsx
@@ -0,0 +1,99 @@
+import { screen } from "@testing-library/react";
+import { describe, expect, mock, test } from "bun:test";
+import { createElement } from "react";
+
+import { CodeBlockWithCopy } from "../../../../src/web/consoles/workbench/components/chat/parts/CodeBlockWithCopy";
+import { renderWithProviders } from "../../test-utils";
+
+const mockWriteText = mock(() => Promise.resolve());
+
+Object.defineProperty(navigator, "clipboard", {
+  configurable: true,
+  get: () => ({ writeText: mockWriteText }),
+});
+
+describe("CodeBlockWithCopy", () => {
+  test("block 模式渲染 CodeHighlighter 和语言标签", () => {
+    renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: true,
+        children: "const x = 1;",
+        lang: "typescript",
+        streamStatus: "done",
+      }),
+    );
+
+    expect(screen.getByText("typescript")).toBeTruthy();
+  });
+
+  test("block 模式渲染复制按钮", () => {
+    renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: true,
+        children: "hello world",
+        lang: "python",
+        streamStatus: "done",
+      }),
+    );
+
+    const copyBtn = screen.getByRole("button");
+    expect(copyBtn).toBeTruthy();
+  });
+
+  test("block 模式语言为空时显示 plaintext", () => {
+    renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: true,
+        children: "some code",
+        lang: "",
+        streamStatus: "done",
+      }),
+    );
+
+    expect(screen.getByText("plaintext")).toBeTruthy();
+  });
+
+  test("block 模式语言为 undefined 时显示 plaintext", () => {
+    renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: true,
+        children: "some code",
+        streamStatus: "done",
+      }),
+    );
+
+    expect(screen.getByText("plaintext")).toBeTruthy();
+  });
+
+  test("inline 模式返回 code 元素", () => {
+    const { container } = renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: false,
+        children: "inline code",
+        className: "language-ts",
+      }),
+    );
+
+    const code = container.querySelector("code.language-ts");
+    expect(code).toBeTruthy();
+    expect(code?.textContent).toBe("inline code");
+  });
+
+  test("点击复制按钮调用 clipboard.writeText", () => {
+    mockWriteText.mockClear();
+
+    renderWithProviders(
+      createElement(CodeBlockWithCopy, {
+        block: true,
+        children: "copy me",
+        lang: "javascript",
+        streamStatus: "done",
+      }),
+    );
+
+    const copyBtn = screen.getByRole("button");
+    copyBtn.click();
+
+    expect(mockWriteText).toHaveBeenCalledWith("copy me");
+  });
+});
diff --git a/tests/web/hooks/use-chat-scroll.test.ts b/tests/web/hooks/use-chat-scroll.test.ts
index 73779a4..ad14502 100644
--- a/tests/web/hooks/use-chat-scroll.test.ts
+++ b/tests/web/hooks/use-chat-scroll.test.ts
@@ -5,6 +5,14 @@ import { describe, expect, mock, test } from "bun:test";
 
 import { useChatScroll } from "../../../src/web/consoles/workbench/components/chat/use-chat-scroll";
 
+interface HookProps {
+  loadingHistory: boolean;
+  messages: UIMessage[];
+  scrollRef: React.RefObject<HTMLDivElement | null>;
+  status: string;
+  viewportElement: HTMLDivElement | null;
+}
+
 interface MockedElement {
   addEventListener: ReturnType<typeof mock>;
   clientHeight: number;
@@ -14,12 +22,12 @@ interface MockedElement {
   scrollTop: number;
 }
 
-function asHTMLElement(el: MockedElement): HTMLElement {
-  return el as unknown as HTMLElement;
+function asRef(el: MockedElement): React.RefObject<HTMLDivElement | null> {
+  return { current: el as unknown as HTMLDivElement };
 }
 
-function asRef(el: MockedElement): React.RefObject<HTMLElement | null> {
-  return { current: asHTMLElement(el) };
+function asViewport(el: MockedElement): HTMLDivElement {
+  return el as unknown as HTMLDivElement;
 }
 
 function createScrollElement(overrides: Partial<MockedElement> = {}): MockedElement {
@@ -38,20 +46,14 @@ describe("useChatScroll", () => {
   test("在底部附近时自动滚动", () => {
     const el = createScrollElement({ scrollHeight: 1000, scrollTop: 920 });
     const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
     const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];
 
     const { rerender } = renderHook(
-      ({
-        messages,
-        scrollRef,
-        status,
-      }: {
-        messages: UIMessage[];
-        scrollRef: React.RefObject<HTMLElement | null>;
-        status: string;
-      }) => useChatScroll({ messages, scrollRef, status }),
+      ({ loadingHistory, messages, scrollRef, status, viewportElement }: HookProps) =>
+        useChatScroll({ loadingHistory, messages, scrollRef, status, viewportElement }),
       {
-        initialProps: { messages, scrollRef, status: "streaming" },
+        initialProps: { loadingHistory: false, messages, scrollRef, status: "streaming", viewportElement },
       },
     );
 
@@ -60,7 +62,7 @@ describe("useChatScroll", () => {
       { id: "2", parts: [], role: "assistant" },
     ] as UIMessage[];
 
-    rerender({ messages: newMessages, scrollRef, status: "streaming" });
+    rerender({ loadingHistory: false, messages: newMessages, scrollRef, status: "streaming", viewportElement });
 
     expect(el.scrollTo).toHaveBeenCalled();
   });
@@ -68,20 +70,14 @@ describe("useChatScroll", () => {
   test("不在底部时不自动滚动", () => {
     const el = createScrollElement({ scrollHeight: 1000, scrollTop: 200 });
     const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
     const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];
 
     const { rerender } = renderHook(
-      ({
-        messages,
-        scrollRef,
-        status,
-      }: {
-        messages: UIMessage[];
-        scrollRef: React.RefObject<HTMLElement | null>;
-        status: string;
-      }) => useChatScroll({ messages, scrollRef, status }),
+      ({ loadingHistory, messages, scrollRef, status, viewportElement }: HookProps) =>
+        useChatScroll({ loadingHistory, messages, scrollRef, status, viewportElement }),
       {
-        initialProps: { messages, scrollRef, status: "streaming" },
+        initialProps: { loadingHistory: false, messages, scrollRef, status: "streaming", viewportElement },
       },
     );
 
@@ -100,32 +96,36 @@ describe("useChatScroll", () => {
       { id: "2", parts: [], role: "assistant" },
     ] as UIMessage[];
 
-    rerender({ messages: newMessages, scrollRef, status: "streaming" });
+    rerender({ loadingHistory: false, messages: newMessages, scrollRef, status: "streaming", viewportElement });
 
     const scrollToCalls = el.scrollTo.mock.calls as unknown[][];
     expect(scrollToCalls.length).toBe(0);
   });
 
-  test("scrollToBottom 使用 smooth 滚动", () => {
+  test("scrollToBottom 使用 instant 滚动", () => {
     const el = createScrollElement({ scrollHeight: 1000, scrollTop: 200 });
     const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
     const messages: UIMessage[] = [];
 
-    const { result } = renderHook(() => useChatScroll({ messages, scrollRef, status: "ready" }));
+    const { result } = renderHook(() => useChatScroll({ messages, scrollRef, status: "ready", viewportElement }));
 
     act(() => {
       result.current.scrollToBottom();
     });
 
-    expect(el.scrollTo).toHaveBeenCalledWith({ behavior: "smooth", top: 1000 });
+    expect(el.scrollTo).toHaveBeenCalledWith({ behavior: "instant", top: 1000 });
   });
 
   test("流式时使用 instant 滚动", () => {
     const el = createScrollElement({ scrollHeight: 1000, scrollTop: 920 });
     const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
     const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];
 
-    renderHook(() => useChatScroll({ messages, scrollRef, status: "streaming" }));
+    renderHook(() =>
+      useChatScroll({ loadingHistory: false, messages, scrollRef, status: "streaming", viewportElement }),
+    );
 
     const calls = el.scrollTo.mock.calls as unknown[][];
     const instantCall = calls.find((call) => {
@@ -134,4 +134,57 @@ describe("useChatScroll", () => {
     });
     expect(instantCall).toBeTruthy();
   });
+
+  test("loadingHistory 从 true 变为 false 时强制 scrollToBottom", async () => {
+    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 0 });
+    const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
+    const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];
+
+    const { rerender } = renderHook(
+      ({ loadingHistory, messages, scrollRef, status, viewportElement }: HookProps) =>
+        useChatScroll({ loadingHistory, messages, scrollRef, status, viewportElement }),
+      {
+        initialProps: { loadingHistory: true, messages, scrollRef, status: "ready", viewportElement },
+      },
+    );
+
+    el.scrollTo.mockClear();
+
+    act(() => {
+      rerender({ loadingHistory: false, messages, scrollRef, status: "ready", viewportElement });
+    });
+
+    await act(async () => {
+      await new Promise((resolve) => setTimeout(resolve, 50));
+    });
+
+    expect(el.scrollTo).toHaveBeenCalledWith({ behavior: "instant", top: el.scrollHeight });
+  });
+
+  test("loadingHistory 不变时不触发强制滚动", () => {
+    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 920 });
+    const scrollRef = asRef(el);
+    const viewportElement = asViewport(el);
+    const messages: UIMessage[] = [];
+
+    const { rerender } = renderHook(
+      ({ loadingHistory, messages, scrollRef, status, viewportElement }: HookProps) =>
+        useChatScroll({ loadingHistory, messages, scrollRef, status, viewportElement }),
+      {
+        initialProps: { loadingHistory: false, messages, scrollRef, status: "ready", viewportElement },
+      },
+    );
+
+    el.scrollTo.mockClear();
+
+    const newMessages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];
+    rerender({ loadingHistory: false, messages: newMessages, scrollRef, status: "ready", viewportElement });
+
+    const instantCalls = el.scrollTo.mock.calls.filter((call: unknown[]) => {
+      const opts = call[0] as Record<string, unknown> | undefined;
+      return opts?.["behavior"] === "instant" && opts?.["top"] === el.scrollHeight;
+    });
+    expect(instantCalls.length).toBe(1);
+  });
 });