refactor(chat): share composer, scroll follow and jump control across both chat surfaces

The rectification session rendered its own textarea (no length ceiling,
no count), its own rAF scroll follow with a sticky-scroll helper, and its
own jump chip styled differently from the main chat's inline Tailwind
button, while the main chat re-ran scrollTo on every streamed token and
added a smooth scroll on settle. ChatComposer now accepts a controlled
value so the rectification surface reuses it without touching the main
draft store; useConversationScrollAnchor owns the follow through a
ResizeObserver, one frame per content change, for both surfaces; a
single JumpToLatestButton replaces both chips; the 720px transcript
override is gone. DESIGN.md records the shared composer, the jump
control, the reading width and the two shadow tokens.

BUG-477 BUG-478

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JUei7K13cYxLHE3Axe4A45

frontend/src/app/globals.css

@@ -1485,6 +1485,42 @@ button:disabled { cursor: default; opacity: .45; }
 .error-message { margin: 12px 0 0; padding: 12px 14px; border-left: 3px solid var(--color-danger); background: var(--color-danger-muted); color: var(--color-danger); font-size: 13px; line-height: 1.6; border-color: var(--color-danger); border-radius: 0 var(--radius-md) var(--radius-md) 0; }
 
 .composer-wrap { position: sticky; bottom: 0; z-index: 2; min-width: 0; border-top: 1px solid color-mix(in srgb, var(--color-border) 70%, transparent); padding: var(--space-3) var(--space-6) var(--space-4); background: var(--color-frosted); backdrop-filter: saturate(130%) blur(20px); }
+/* Jump to latest: shared by both chat surfaces. Hangs off the composer wrap's top
+   edge so it never reflows the transcript or the composer. */
+.jump-to-latest {
+  position: absolute;
+  inset-inline: 0;
+  bottom: 100%;
+  z-index: 3;
+  display: flex;
+  justify-content: center;
+  padding-bottom: var(--space-3);
+  pointer-events: none;
+}
+.jump-to-latest__button {
+  pointer-events: auto;
+  min-height: 44px;
+  min-width: 44px;
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 0 var(--space-4);
+  border: 1px solid var(--color-border);
+  border-radius: 999px;
+  background: var(--color-canvas);
+  color: var(--color-ink);
+  box-shadow: var(--shadow-elevated);
+  font: inherit;
+  font-size: var(--type-body-sm);
+  cursor: pointer;
+  transition: background-color 120ms ease-out;
+}
+.jump-to-latest__button svg { width: 16px; height: 16px; flex: 0 0 auto; }
+.jump-to-latest__button:hover { background: var(--color-canvas-muted); }
+.jump-to-latest__button:focus-visible {
+  outline: 3px solid color-mix(in srgb, var(--color-focus) 56%, transparent);
+  outline-offset: 3px;
+}
 .composer { width: min(760px, 100%); display: flex; align-items: flex-end; gap: 10px; margin: 0 auto; border: 1px solid var(--color-border); transition: border-color 140ms ease-out; min-height: 60px; padding: var(--space-2) var(--space-2) var(--space-2) var(--space-4); border-color: var(--color-border-strong); border-radius: var(--radius-lg); background: var(--color-canvas); box-shadow: 0 0 0 1px color-mix(in srgb, var(--color-border) 42%, transparent); }
 .composer:focus-within { border-color: var(--color-action); box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-action) 15%, transparent); }
 .composer textarea { min-width: 0; min-height: 44px; max-height: 128px; flex: 1; resize: none; padding: 11px 0 8px; border: 0; outline: 0; background: transparent; color: var(--color-ink); line-height: 1.5; font-size: 16px; }
@@ -2608,7 +2644,6 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 }
 .rectification-workspace__chat .message-list {
   width: 100%;
-  max-width: 720px;
   padding-bottom: var(--rectification-jump-clearance);
 }
 .conversation.is-rectification .message-actions {
@@ -2618,32 +2653,6 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
   position: relative;
   z-index: 2;
 }
-.rectification-jump-latest {
-  position: absolute;
-  inset-inline: 0;
-  bottom: 100%;
-  z-index: 3;
-  display: flex;
-  justify-content: center;
-  padding-bottom: var(--space-2);
-  pointer-events: none;
-}
-.rectification-jump-latest button {
-  pointer-events: auto;
-  min-height: 44px;
-  min-width: 44px;
-  padding: 0 var(--space-4);
-  border: 1px solid var(--color-border);
-  border-radius: 999px;
-  background: var(--color-canvas);
-  color: var(--color-ink);
-  box-shadow: var(--shadow-soft);
-  font-size: var(--type-caption);
-}
-.rectification-jump-latest button:focus-visible {
-  outline: 3px solid color-mix(in srgb, var(--color-focus) 56%, transparent);
-  outline-offset: 3px;
-}
 .rectification-workspace.is-compact.is-board-open .rectification-workspace__chat .composer-wrap {
   z-index: 0;
   visibility: hidden;

frontend/src/app/page.tsx

@@ -4,7 +4,7 @@ import "@/app/site-styles";
 import Link from "next/link";
 import dynamic from "next/dynamic";
 import { useRouter } from "next/navigation";
-import { ArrowDown, Sparkles } from "lucide-react";
+import { Sparkles } from "lucide-react";
 import { InlineSpinner } from "@/components/inline-spinner";
 import { useEffect, useRef, useState } from "react";
 import type { FormEvent, KeyboardEvent } from "react";
@@ -33,6 +33,7 @@ import { ChatTranscript, type ChatTranscriptActions } from "@/components/chat-tr
 import { ModelSelector } from "@/components/model-selector";
 import { OnboardingRedeemPaywall } from "@/components/onboarding-redeem-paywall";
 import { ChatComposer } from "@/components/chat-composer";
+import { JumpToLatestButton } from "@/components/jump-to-latest-button";
 import { ComposerCharacterRemaining } from "@/components/composer-character-remaining";
 import { SidebarInset, SidebarProvider, SidebarTrigger } from "@/components/ui/sidebar";
 import { composerDraftSnapshot, setComposerDraft } from "@/lib/composer-draft";
@@ -1240,15 +1241,6 @@ export default function Home() {
     setStarterGreetingSelection(Math.random());
   }, [starterHomeVisible]);
 
-  useEffect(() => {
-    if (starterHomeVisible) return;
-    const container = conversation.current;
-    if (!container) return;
-    if (!conversationAnchor.anchored) return;
-    const reduceMotion = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
-    container.scrollTo({ top: container.scrollHeight, behavior: isLoading || reduceMotion ? "auto" : "smooth" });
-  }, [activeSessionId, activeSession?.messages.length, activeStreamingText, conversationAnchor.anchored, isLoading, onboardingPending, onboardingStep, presetMessageFinished, profileComplete, starterHomeVisible]);
-
   useEffect(() => {
     if (hydrated && accountId && !profileComplete && onboardingStep === "name" && presetMessageFinished && activeAccountDialog === null) {
       composerInput.current?.focus();
@@ -1924,17 +1916,7 @@ export default function Home() {
 
         {!rectificationSurfaceOpen && !onboardingFormActive && <div className={`composer-wrap ${starterHomeVisible ? "composer-wrap-starter" : ""}`}>
           {jumpToLatestVisible && (
-            <div className="pointer-events-none absolute inset-x-0 bottom-full flex justify-center pb-3">
-              <button
-                className="pointer-events-auto inline-flex min-h-11 min-w-11 items-center gap-1.5 rounded-full border border-border bg-canvas px-4 text-sm text-ink shadow-md transition-colors outline-none hover:bg-canvas-muted focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50"
-                type="button"
-                aria-label="跳到最新"
-                onClick={conversationAnchor.anchorToLatest}
-              >
-                <ArrowDown aria-hidden="true" className="size-4" />
-                跳到最新
-              </button>
-            </div>
+            <JumpToLatestButton onClick={conversationAnchor.anchorToLatest} />
           )}
           <ChatComposer
             inputRef={composerInput}

frontend/src/components/chat-composer.tsx

@@ -24,6 +24,14 @@ export function useComposerDraft(): string {
 
 type ChatComposerProps = {
   readonly inputRef: RefObject<HTMLTextAreaElement | null>;
+  /**
+   * A surface that owns its own draft (the rectification session) passes it here;
+   * the main chat leaves it undefined and the composer reads the draft store.
+   */
+  readonly value?: string;
+  readonly remainingId?: string;
+  /** Extra description (a question stem shown above the field) merged with the count id. */
+  readonly describedBy?: string;
   readonly inputLabel: string;
   readonly placeholder: string;
   readonly maxLength: number;
@@ -41,6 +49,9 @@ type ChatComposerProps = {
 
 export function ChatComposer({
   inputRef,
+  value,
+  remainingId = composerRemainingId,
+  describedBy,
   inputLabel,
   placeholder,
   maxLength,
@@ -55,15 +66,17 @@ export function ChatComposer({
   onKeyDown,
   onStop,
 }: ChatComposerProps) {
-  const draft = useComposerDraft();
+  const storeDraft = useComposerDraft();
+  const draft = value ?? storeDraft;
   const showRemaining = characterRemainingVisible(draft.length, maxLength);
+  const describedByIds = [describedBy, showRemaining ? remainingId : undefined].filter(Boolean).join(" ") || undefined;
 
   return (
     <form className="composer" onSubmit={onSubmit}>
       <Textarea
         ref={inputRef}
         aria-label={inputLabel}
-        aria-describedby={showRemaining ? composerRemainingId : undefined}
+        aria-describedby={describedByIds}
         placeholder={placeholder}
         rows={1}
         maxLength={maxLength}

frontend/src/components/jump-to-latest-button.tsx

@@ -0,0 +1,25 @@
+"use client";
+
+import { ArrowDown } from "lucide-react";
+
+/**
+ * The "back to the newest turn" control both chat surfaces show once the
+ * reader has scrolled away from the bottom. It hangs off the composer's top
+ * edge (the composer wrap is its containing block) so it never reflows the
+ * transcript or the composer, and it is a real button in document order.
+ */
+export function JumpToLatestButton({ onClick }: Readonly<{ onClick: () => void }>) {
+  return (
+    <div className="jump-to-latest">
+      <button
+        type="button"
+        className="jump-to-latest__button"
+        aria-label="跳到最新"
+        onClick={onClick}
+      >
+        <ArrowDown aria-hidden="true" />
+        跳到最新
+      </button>
+    </div>
+  );
+}

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

@@ -1,6 +1,5 @@
 "use client";
 
-import { ArrowUp, Square } from "lucide-react";
 import { useCallback, useEffect, useId, useLayoutEffect, useRef, useState } from "react";
 import { createPortal } from "react-dom";
 import { parseAgentReply } from "@/lib/agent-reply";
@@ -49,7 +48,6 @@ import {
   isPublicRectificationTool,
 } from "@/lib/rectification-agentic/v9/public-receipt";
 import { userFacingRunFailure, isIncompleteRunBanner } from "@/lib/rectification-agentic/v9/run-diagnostic";
-import { isNearBottom, shouldShowJumpToLatest } from "@/lib/rectification-sticky-scroll";
 import {
   CHOICE_ACTION,
   STOP_ACTION,
@@ -66,7 +64,11 @@ import {
   type RectificationChoiceCard as ChoiceCardModel,
 } from "@/lib/rectification-agentic/v9/choice-card";
 import type { PublicLanguageModel } from "@/lib/public-models";
+import { useConversationScrollAnchor } from "@/hooks/use-conversation-scroll-anchor";
+import { CharacterRemaining } from "./character-remaining";
+import { ChatComposer } from "./chat-composer";
 import { ChatMessageRow } from "./chat-message-row";
+import { JumpToLatestButton } from "./jump-to-latest-button";
 import {
   ChatMessageActions,
   toggleChatMessageFeedback,
@@ -75,7 +77,6 @@ import { ModelSelector } from "./model-selector";
 import { RectificationBoard, RectificationBoardPeek } from "./rectification-board";
 import { RectificationChoiceCard } from "./rectification-choice-card";
 import { Button } from "./ui/button";
-import { Textarea } from "./ui/textarea";
 
 type PersistedTurn = Readonly<{
   id: string;
@@ -97,6 +98,9 @@ type PersistedTurn = Readonly<{
   }> | null;
 }>;
 
+/** Same ceiling as the main chat composer, so both surfaces count down the same way. */
+const RECTIFICATION_COMPOSER_MAX_LENGTH = 500;
+
 type CandidateResult = RectificationCandidateResult | null;
 type CurrentQuestionModel = Readonly<{
   kind: "choice" | "collect_spoken";
@@ -317,17 +321,17 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
   const openingStarted = useRef(false);
   const previousBoardResult = useRef<CandidateResult>(null);
   const runAbort = useRef<AbortController | null>(null);
-  const followTailRef = useRef(true);
-  const scrollFrameRef = useRef<number | null>(null);
   const choiceActionIds = useRef(new Map<string, string>());
-  const choiceCardsOpen = useRef(false);
-  const [showJumpToLatest, setShowJumpToLatest] = useState(false);
   const [compactBoard, setCompactBoard] = useState(false);
   const [boardOpen, setBoardOpen] = useState(false);
   const [boardDiff, setBoardDiff] = useState(() => diffRectificationBoard(null, null));
   const boardId = useId();
   const boardTitleId = useId();
   const collectSpokenPromptId = useId();
+  const composerRemainingId = useId();
+  // The same anchor-and-follow the consultation surface uses: streamed tokens and
+  // new cards land the viewport on the bottom only while the reader is there.
+  const conversationAnchor = useConversationScrollAnchor(conversation, true, caseId);
 
   useLayoutEffect(() => {
     const query = window.matchMedia(`(max-width: ${RECTIFICATION_BOARD_SPLIT_MIN_PX - 1}px)`);
@@ -358,50 +362,6 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
     onPendingChange?.(value);
   }, [onPendingChange]);
 
-  const updateFollowState = useCallback(() => {
-    const viewport = conversation.current;
-    if (!viewport) return;
-    const nearBottom = isNearBottom(viewport.scrollHeight, viewport.scrollTop, viewport.clientHeight);
-    followTailRef.current = nearBottom;
-    setShowJumpToLatest(shouldShowJumpToLatest(
-      viewport.scrollHeight,
-      viewport.scrollTop,
-      viewport.clientHeight,
-      choiceCardsOpen.current,
-    ));
-  }, []);
-
-  const scrollToLatest = useCallback((behavior: ScrollBehavior = "smooth") => {
-    const viewport = conversation.current;
-    if (!viewport) return;
-    followTailRef.current = true;
-    setShowJumpToLatest(false);
-    const reduceMotion = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
-    viewport.scrollTo({
-      top: viewport.scrollHeight,
-      behavior: reduceMotion ? "auto" : behavior,
-    });
-  }, []);
-
-  const followLatestContent = useCallback(() => {
-    if (!followTailRef.current) return;
-    if (scrollFrameRef.current !== null) {
-      cancelAnimationFrame(scrollFrameRef.current);
-    }
-    scrollFrameRef.current = requestAnimationFrame(() => {
-      const container = conversation.current;
-      if (!container || !followTailRef.current) return;
-      container.scrollTop = container.scrollHeight;
-    });
-  }, []);
-
-  useLayoutEffect(() => {
-    followLatestContent();
-    return () => {
-      if (scrollFrameRef.current !== null) cancelAnimationFrame(scrollFrameRef.current);
-    };
-  }, [busy, candidateResult, choiceCard, error, messages, savedTime, followLatestContent]);
-
   // Candidate snapshot comes from the persisted Candidate Snapshot API, never
   // from parsing agent text or hidden sentinels.
   const applyCaseSnapshot = useCallback((payload: {
@@ -1071,10 +1031,6 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
     && !readonly
     && regeneratingMessageKey === null,
   );
-  useLayoutEffect(() => {
-    choiceCardsOpen.current = showLiveChoiceCard;
-    updateFollowState();
-  }, [showLiveChoiceCard, updateFollowState]);
   const showSelectionCards = Boolean(
     candidateResult?.selectionAllowed
     && candidateResult?.canAdopt
@@ -1141,7 +1097,6 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
           className="conversation is-rectification"
           aria-label="生时校正对话"
           aria-busy={busy || regeneratingMessageKey !== null}
-          onScroll={updateFollowState}
         >
           <div className="message-list">
           {pendingConsultationQuestion?.trim() && (
@@ -1284,26 +1239,17 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
       </section>
 
         <div className="composer-wrap">
-          {showJumpToLatest && (
-            <div className="rectification-jump-latest">
-              <button
-                type="button"
-                aria-label="回到最新"
-                onClick={() => scrollToLatest("smooth")}
-              >
-                回到最新
-              </button>
-            </div>
+          {!conversationAnchor.anchored && (
+            <JumpToLatestButton onClick={conversationAnchor.anchorToLatest} />
           )}
-          <form className="composer" onSubmit={submit}>
-          <Textarea
-            ref={composer}
-            aria-label={readonly ? "该校正已结束，只能查看历史" : "继续描述你的经历或回答"}
-            aria-describedby={collectSpokenPrompt && !showLiveChoiceCard && !readonly
+          <ChatComposer
+            inputRef={composer}
+            describedBy={collectSpokenPrompt && !showLiveChoiceCard && !readonly
               ? collectSpokenPromptId
               : undefined}
             value={draft}
-            disabled={!canSend}
+            remainingId={composerRemainingId}
+            inputLabel={readonly ? "该校正已结束，只能查看历史" : "继续描述你的经历或回答"}
             placeholder={readonly
               ? "该校正已结束，只能查看历史；需要再次校正请新建。"
               : showLiveChoiceCard
@@ -1311,6 +1257,14 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
                 : collectSpokenPrompt
                   ? "请回答上面的问题…"
                   : "继续说你记得的人生经历，或回答刚才的问题…"}
+            maxLength={RECTIFICATION_COMPOSER_MAX_LENGTH}
+            inputDisabled={!canSend}
+            submitLabel="发送"
+            submitBlocked={!canSend}
+            stopVisible={busy}
+            stopLabel="停止回答"
+            stopTitle="停止当前推理，已生成内容会保留"
+            onSubmit={submit}
             onChange={(event) => setDraft(event.target.value)}
             onKeyDown={(event) => {
               if (event.key === "Enter" && !event.shiftKey && !event.nativeEvent.isComposing) {
@@ -1318,33 +1272,22 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
                 event.currentTarget.form?.requestSubmit();
               }
             }}
+            onStop={stopRun}
           />
-          {busy ? (
-            <Button
-              className="composer-stop"
-              aria-label="停止回答"
-              title="停止当前推理，已生成内容会保留"
-              size="icon"
-              type="button"
-              onClick={stopRun}
-            >
-              <Square aria-hidden="true" />
-            </Button>
-          ) : (
-            <Button aria-label="发送" disabled={!draft.trim() || !canSend} size="icon" type="submit">
-              <ArrowUp aria-hidden="true" />
-            </Button>
-          )}
-        </form>
 
-        <div className="composer-footer">
-          <ModelSelector
-            models={models}
-            selectedModelId={selectedModelId}
-            disabled={busy || readonly}
-            onSelect={onSelectModel}
-          />
-        </div>
+          <div className="composer-footer">
+            <ModelSelector
+              models={models}
+              selectedModelId={selectedModelId}
+              disabled={busy || readonly}
+              onSelect={onSelectModel}
+            />
+            <CharacterRemaining
+              id={composerRemainingId}
+              length={draft.length}
+              maxLength={RECTIFICATION_COMPOSER_MAX_LENGTH}
+            />
+          </div>
         </div>
       </div>
       <RectificationBoard

frontend/src/hooks/use-conversation-scroll-anchor.ts

@@ -24,15 +24,28 @@ export function nextAnchorState(anchored: boolean, distanceFromBottom: number, s
   return scrolledUp ? false : anchored;
 }
 
+/**
+ * Owns both halves of "follow the conversation": whether the reader is
+ * anchored to the bottom (a scroll listener), and landing the viewport on the
+ * newest content while they are (a resize observer over the scroller's
+ * children, one frame per change). Both chat surfaces use this one hook, so
+ * streamed tokens never call scrollTo directly and settlement never adds a
+ * second, smooth scroll on top of the follow.
+ */
 export function useConversationScrollAnchor(
-  container: RefObject<HTMLDivElement | null>,
+  container: RefObject<HTMLElement | null>,
   active: boolean,
   resetKey: string,
 ): ConversationScrollAnchor {
   const [anchor, setAnchor] = useState<AnchorState>({ key: resetKey, anchored: true });
   const lastScrollTop = useRef(0);
+  const anchoredRef = useRef(true);
   const anchored = anchor.key === resetKey ? anchor.anchored : true;
 
+  useEffect(() => {
+    anchoredRef.current = anchored;
+  }, [anchored]);
+
   useEffect(() => {
     const element = container.current;
     if (!active || !element) return;
@@ -61,6 +74,48 @@ export function useConversationScrollAnchor(
     };
   }, [active, container, resetKey]);
 
+  // Follow: while anchored, any change in the scroller's content height lands the
+  // viewport on the bottom, at most once per frame. Switching conversations
+  // (resetKey) lands there immediately.
+  useEffect(() => {
+    const element = container.current;
+    if (!active || !element) return;
+    let frame = 0;
+    const follow = () => {
+      frame = 0;
+      if (!anchoredRef.current) return;
+      element.scrollTop = element.scrollHeight;
+    };
+    const requestFollow = () => {
+      if (frame) return;
+      frame = window.requestAnimationFrame(follow);
+    };
+    requestFollow();
+    if (typeof ResizeObserver === "undefined") {
+      return () => {
+        if (frame) window.cancelAnimationFrame(frame);
+      };
+    }
+    const sizes = new ResizeObserver(requestFollow);
+    const observeChildren = () => {
+      sizes.disconnect();
+      for (const child of Array.from(element.children)) sizes.observe(child);
+    };
+    observeChildren();
+    const children = typeof MutationObserver === "undefined"
+      ? null
+      : new MutationObserver(() => {
+        observeChildren();
+        requestFollow();
+      });
+    children?.observe(element, { childList: true });
+    return () => {
+      sizes.disconnect();
+      children?.disconnect();
+      if (frame) window.cancelAnimationFrame(frame);
+    };
+  }, [active, container, resetKey]);
+
   return {
     anchored,
     anchorToLatest: () => {

frontend/src/lib/rectification-sticky-scroll.ts

@@ -1,43 +0,0 @@
-/**
- * Sticky follow for a streaming message viewport.
- *
- * Auto-follow only when the user is already near the bottom. Streaming
- * updates must not steal scrollTop after the user moves upward.
- */
-
-export const RECTIFICATION_NEAR_BOTTOM_PX = 96;
-/** Keep the jump chip hidden while a choice card still occupies the composer overlay band. */
-export const RECTIFICATION_CHOICE_NEAR_BOTTOM_PX = 360;
-
-export function distanceFromBottom(
-  scrollHeight: number,
-  scrollTop: number,
-  clientHeight: number,
-): number {
-  return scrollHeight - scrollTop - clientHeight;
-}
-
-export function isNearBottom(
-  scrollHeight: number,
-  scrollTop: number,
-  clientHeight: number,
-  thresholdPx = RECTIFICATION_NEAR_BOTTOM_PX,
-): boolean {
-  return distanceFromBottom(scrollHeight, scrollTop, clientHeight) <= thresholdPx;
-}
-
-export function shouldShowJumpToLatest(
-  scrollHeight: number,
-  scrollTop: number,
-  clientHeight: number,
-  choiceCardOpen = false,
-): boolean {
-  const distance = distanceFromBottom(scrollHeight, scrollTop, clientHeight);
-  if (distance <= RECTIFICATION_NEAR_BOTTOM_PX) return false;
-  if (choiceCardOpen && distance <= RECTIFICATION_CHOICE_NEAR_BOTTOM_PX) return false;
-  return true;
-}
-
-export function shouldFollowLatest(followTail: boolean): boolean {
-  return followTail === true;
-}