fix: 修复研究助手首屏滚动与欢迎区布局

frontend/src/ai/AssistantDialogue.tsx

@@ -33,6 +33,7 @@ export function AssistantDialogue({
   timezone?: string;
   jobs: Job[];
 }) {
+  if (!messages.length) return null;
   const sources = new Map(messages.map((message) => [message.id, message]));
   const chats: Message[] = messages.map((message) => ({
     id: message.id,

frontend/src/ai/ChatPanel.tsx

@@ -10,7 +10,7 @@ import {
   IconPlus,
   IconChevronRight,
 } from "@douyinfe/semi-icons";
-import { contextLabel, contextReferences, researchPrompts } from "./workspace";
+import { contextLabel, contextReferences } from "./workspace";
 import { chatTransport } from "./transport";
 import { runLabels } from "./types";
 import type {
@@ -58,7 +58,7 @@ export function ChatPanel({
   const [loading, setLoading] = useState(false);
   const root = useRef<HTMLElement>(null);
   const input = useRef<HTMLDivElement>(null);
-  const bottom = useRef<HTMLDivElement>(null);
+  const messagesViewport = useRef<HTMLDivElement>(null);
   const previousFocus = useRef<HTMLElement | null>(null);
   const seenChanges = useRef(new Set<string>());
   const current = useRef({ conversationId, context });
@@ -206,7 +206,7 @@ export function ChatPanel({
     const editor = input.current?.querySelector<HTMLElement>(
       '[contenteditable="true"]',
     );
-    if (editor) editor.focus();
+    if (editor) editor.focus({ preventScroll: true });
     else
       root.current
         ?.querySelector<HTMLButtonElement>('button[aria-label="收起研究助手"]')
@@ -226,7 +226,11 @@ export function ChatPanel({
     };
   }, [open]);
   useEffect(() => {
-    if (open) bottom.current?.scrollIntoView({ block: "nearest" });
+    if (!open || !messagesViewport.current) return;
+    // Scroll only the message region; empty conversations always start at the welcome.
+    messagesViewport.current.scrollTop = chat.messages.length
+      ? messagesViewport.current.scrollHeight
+      : 0;
   }, [chat.messages, open]);
 
   async function createConversation() {
@@ -409,7 +413,12 @@ export function ChatPanel({
         />
       )}
       {failure && <Banner type="danger" description={failure} />}
-      <div className="ai-messages" aria-live="polite" aria-busy={streaming}>
+      <div
+        ref={messagesViewport}
+        className="ai-messages"
+        aria-live="polite"
+        aria-busy={streaming}
+      >
         {loading && <Spin />}
         {!chat.messages.length && (
           <div className="ai-empty">
@@ -428,7 +437,9 @@ export function ChatPanel({
                 开始新会话
               </Button>
             )}
-            <span>修改和任务操作会先展示预览，确认后执行。</span>
+            <p className="ai-empty-note">
+              修改和任务操作会先展示预览，确认后执行。
+            </p>
           </div>
         )}
         <AssistantDialogue
@@ -460,7 +471,6 @@ export function ChatPanel({
             )}
           </div>
         )}
-        <div ref={bottom} />
       </div>
       <footer className="ai-composer" ref={input}>
         <div className="ai-context">{contextLabel(context)}</div>
@@ -477,14 +487,6 @@ export function ChatPanel({
           busy={!!activeRun || streaming}
           onSubmit={() => void send()}
           onStop={activeRun ? () => void stop() : undefined}
-          prompts={researchPrompts(context)}
-          hint={
-            context.page === "datasets"
-              ? context.unsaved_field_selection
-                ? "字段选择尚未保存；请先保存为固定研究输入。未保存备注不会发送。"
-                : "引用随当前页面更新，未保存备注不会发送。"
-              : "引用随当前页面更新。修改和任务操作会先展示预览，确认后执行。"
-          }
         />
       </footer>
     </aside>

frontend/src/ai/style.css

@@ -146,7 +146,7 @@
   border-radius: 8px;
 }
 .ai-empty {
-  margin: 32px 0;
+  margin: 16px 0;
   color: var(--muted);
   line-height: 24px;
 }
@@ -159,8 +159,7 @@
 .ai-empty .semi-button {
   margin-top: var(--space-3);
 }
-.ai-empty span {
+.ai-empty-note {
-  display: block;
   font-size: 12px;
   line-height: 20px;
   margin-top: var(--space-4);
@@ -307,9 +306,14 @@
   border-radius: 8px;
   background: var(--semi-color-ai-background-top);
 }
+/* The outer message region owns scrolling, including welcome and run status. */
 .ai-messages .semi-ai-chat-dialogue {
+  height: auto;
   min-height: 0;
 }
+.ai-messages .semi-ai-chat-dialogue-list {
+  overflow: visible;
+}
 .ai-messages .semi-ai-chat-dialogue-inner {
   min-width: 0;
 }

frontend/tests/ai-layout.spec.ts

@@ -0,0 +1,71 @@
+import { expect, test } from "@playwright/test";
+
+for (const viewport of [
+  { width: 1440, height: 850 },
+  { width: 390, height: 650 },
+]) {
+  test(`assistant opens with welcome and composer in view at ${viewport.width}`, async ({
+    page,
+  }) => {
+    await page.setViewportSize(viewport);
+    await page.route("**/api/v1/ai/conversations", (route) =>
+      route.fulfill({ json: [] }),
+    );
+    await page.route("**/api/v1/account", async (route) => {
+      const response = await route.fetch();
+      await route.fulfill({
+        json: { ...(await response.json()), theme: "dark" },
+      });
+    });
+    if (viewport.width === 1440)
+      await page.route("**/api/v1/ai/settings", (route) =>
+        route.fulfill({ json: { enabled: true, ready: true } }),
+      );
+    await page.goto("/");
+    await page
+      .getByLabel("密码", { exact: true })
+      .fill("browser-test-password");
+    await page.getByRole("button", { name: "进入工作空间" }).click();
+    await page.evaluate(() => document.body.setAttribute("theme-mode", "dark"));
+    await page.getByRole("button", { name: "切换研究助手" }).click();
+    const chat = page.getByRole("complementary", { name: "AI 研究助手" });
+
+    await expect(
+      chat.getByRole("heading", { name: "从当前研究出发" }),
+    ).toBeInViewport();
+    await expect(
+      chat.getByRole("button", { name: "发送", exact: true }),
+    ).toBeInViewport();
+    await expect(page.locator("body")).toHaveAttribute("theme-mode", "dark");
+    await page.screenshot({
+      path: `../output/playwright/ai-layout-${viewport.width}.png`,
+    });
+    const start = chat.getByRole("button", { name: "开始新会话", exact: true });
+    expect(
+      await start.evaluate((button) => {
+        const outer = button.getBoundingClientRect();
+        return [...button.querySelectorAll("span")].every((span) => {
+          const inner = span.getBoundingClientRect();
+          return inner.top >= outer.top && inner.bottom <= outer.bottom;
+        });
+      }),
+    ).toBe(true);
+    await expect(
+      chat.locator(".research-ai-prompts, .research-ai-hint"),
+    ).toHaveCount(0);
+    expect(
+      await chat.evaluate((el) => el.scrollHeight <= el.clientHeight),
+    ).toBe(true);
+    await chat.getByRole("button", { name: "收起研究助手" }).click();
+    await page.getByRole("button", { name: "切换研究助手" }).click();
+    await expect(
+      chat.getByRole("heading", { name: "从当前研究出发" }),
+    ).toBeInViewport();
+    await page.evaluate(() =>
+      document.body.setAttribute("theme-mode", "light"),
+    );
+    await page.screenshot({
+      path: `../output/playwright/ai-layout-${viewport.width}-light.png`,
+    });
+  });
+}

frontend/tests/ai.spec.ts

@@ -84,13 +84,13 @@ test("model settings, text stream, contextual query, confirmation and preserved
   await page.getByRole("button", { name: "Alpha 管理", exact: true }).click();
   await page.getByRole("textbox", { name: "搜索 Alpha" }).fill("TEST0001");
   await page.getByRole("button", { name: "查询", exact: true }).click();
+  // Global tools sit below drawers; open the assistant before the Alpha detail.
+  await page.getByRole("button", { name: "切换研究助手" }).click();
   await page.locator(".alpha-link").click();
   await page.getByRole("tab", { name: "研究信息" }).click();
   await page
     .getByRole("textbox", { name: "研究备注" })
     .fill("尚未保存的人工研究草稿");
-  // A global launcher must remain reachable when the detail mask is open.
-  await page.getByRole("button", { name: "切换研究助手" }).click();
   const chat = page.getByRole("complementary", { name: "AI 研究助手" });
   await chat.getByRole("button", { name: "新会话", exact: true }).click();
   await expect(chat.locator(".research-ai-reference")).toContainText(
@@ -430,11 +430,6 @@ test("AI composer preserves literal text, IME input and drafts while generating"
     )
       sent.push(request.postDataJSON().message);
   });
-  await chat
-    .getByRole("button", { name: "查询当前研究对象与已有结果", exact: true })
-    .click();
-  await expect(input).toHaveText("查询当前研究对象与已有结果");
-  expect(sent).toEqual([]);
   await input.fill("SLOW <字段>");
   await input.dispatchEvent("keydown", {
     key: "Enter",