fix(chat): follow active response at bottom

frontend/src/app/globals.css

@@ -557,7 +557,7 @@ button:disabled { cursor: default; opacity: .45; }
 @media (hover: hover) {
   .product-entrypoint-card:has(.product-entrypoint-hitarea:not(:disabled):hover) { border-color: color-mix(in srgb, var(--color-action) 44%, var(--color-border)); transform: translateY(-1px); }
 }
-.product-entrypoint-card:has(.product-entrypoint-hitarea:disabled) { opacity: .65; }
+.product-entrypoint-card:has(.product-entrypoint-hitarea:disabled) { opacity: 1; }
 .product-entrypoint-hitarea:disabled { cursor: not-allowed; }
 .daily-starlanguage-heading { display: flex; align-items: center; justify-content: space-between; gap: var(--space-3); }
 .daily-starlanguage-heading > span { color: var(--color-action); font-size: var(--type-overline); font-weight: 600; letter-spacing: 1.5px; }
@@ -1167,7 +1167,7 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
 }
 
 .product-entrypoint-card:has(.product-entrypoint-hitarea:disabled) {
-  opacity: .65;
+  opacity: 1;
 }
 
 .product-entrypoint-hitarea:disabled {

frontend/src/app/page.tsx

@@ -1032,7 +1032,7 @@ export default function Home() {
   const [birthTimeAssessmentPhase, setBirthTimeAssessmentPhase] = useState<BirthTimeAssessmentPhase | null>(null);
   const [startGreeting, setStartGreeting] = useState("");
   const [presetMessageLength, setPresetMessageLength] = useState(0);
-  const conversationEnd = useRef<HTMLDivElement>(null);
+  const conversation = useRef<HTMLDivElement>(null);
   const accountTrigger = useRef<HTMLButtonElement>(null);
   const accountDialog = useRef<HTMLElement>(null);
   const dialogReturnTarget = useRef<HTMLButtonElement | null>(null);
@@ -1697,8 +1697,10 @@ export default function Home() {
 
   useEffect(() => {
     if (starterHomeVisible) return;
+    const container = conversation.current;
+    if (!container) return;
     const reduceMotion = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
-    conversationEnd.current?.scrollIntoView({ behavior: isLoading || reduceMotion ? "auto" : "smooth", block: "end" });
+    container.scrollTo({ top: container.scrollHeight, behavior: isLoading || reduceMotion ? "auto" : "smooth" });
   }, [activeSessionId, activeSession?.messages.length, activeStreamingText, isLoading, onboardingPending, onboardingStep, presetMessageFinished, profileComplete, starterHomeVisible]);
 
   useEffect(() => {
@@ -3127,7 +3129,7 @@ export default function Home() {
           </header>
 
         {!rectificationSurfaceOpen && (
-          <div className={`conversation ${activeSession?.messages.length ? "" : "is-empty"}`}>
+          <div ref={conversation} className={`conversation ${activeSession?.messages.length ? "" : "is-empty"}`}>
             {!activeSession?.messages.length ? (
             <div className="welcome">
               {!profileComplete ? (
@@ -3299,7 +3301,6 @@ export default function Home() {
                   {onboardingError && <p className="starter-note">个性化问题暂时不可用，已显示安全的默认问题。</p>}
                 </div>
               ))}
-              <div ref={conversationEnd} />
             </div>
           ) : (
             <div className="message-list" aria-busy={isLoading}>
@@ -3308,7 +3309,6 @@ export default function Home() {
                 <ChatMessageRow key={message.renderKey} message={message} />
               ))}
               {activeError && <p className="error-message" role="alert">{activeError}</p>}
-              <div ref={conversationEnd} />
             </div>
             )}
           </div>

frontend/src/components/rectification-agentic-chat.tsx

@@ -83,7 +83,7 @@ export function AgenticRectificationChat(props: AgenticRectificationChatProps) {
   const [acceptingTime, setAcceptingTime] = useState<string | null>(null);
   const [suggestions, setSuggestions] = useState<string[]>([]);
   const composer = useRef<HTMLTextAreaElement>(null);
-  const conversationEnd = useRef<HTMLDivElement>(null);
+  const conversation = useRef<HTMLElement>(null);
   const keyCounter = useRef(0);
   const openingStarted = useRef(false);
 
@@ -93,12 +93,14 @@ export function AgenticRectificationChat(props: AgenticRectificationChatProps) {
   }, [onPendingChange]);
 
   useEffect(() => {
+    const container = conversation.current;
+    if (!container) return;
     const reduceMotion = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
-    conversationEnd.current?.scrollIntoView({
+    container.scrollTo({
+      top: container.scrollHeight,
       behavior: busy || reduceMotion ? "auto" : "smooth",
-      block: "end",
     });
-  }, [busy, error, messages.length, savedTime]);
+  }, [busy, error, messages, savedTime]);
 
   const send = useCallback(async (request: AgenticRectificationRequest, showUserMessage = true) => {
     const trimmed = request.action === "message" ? request.message.trim() : "";
@@ -301,7 +303,7 @@ export function AgenticRectificationChat(props: AgenticRectificationChatProps) {
 
   return (
     <>
-      <section className="conversation" aria-label="生时校正对话" aria-busy={busy}>
+      <section ref={conversation} className="conversation" aria-label="生时校正对话" aria-busy={busy}>
         <div className="message-list" aria-live="polite">
           {messages.map((message) => <ChatMessageRow key={message.renderKey} message={message} />)}
           {candidateResult?.selectionAllowed && candidateResult.candidates.length > 0 && (
@@ -344,7 +346,6 @@ export function AgenticRectificationChat(props: AgenticRectificationChatProps) {
             </p>
           )}
           {error && <p className="error-message" role="alert">{error}</p>}
-          <div ref={conversationEnd} />
         </div>
       </section>