From 2798c0894fe15a5a7ebcf4f1aa3e4164d5aaf8d2 Mon Sep 17 00:00:00 2001
From: Echo <ChaosExAnima@users.noreply.github.com>
Date: Thu, 27 Aug 2026 13:51:51 +0000
Subject: [PATCH] Composer redesign: Autocomplete (#40276)

---
 .../autosuggest/autosuggest.stories.tsx       | 119 +++++++++
 .../mastodon/components/autosuggest/hooks.tsx | 233 ++++++++++++++++++
 .../mastodon/components/autosuggest/items.tsx |  97 ++++++++
 .../mastodon/components/autosuggest/list.tsx  | 114 +++++++++
 .../components/autosuggest/styles.module.scss |  59 +++++
 .../mastodon/components/autosuggest/types.ts  |  35 +++
 .../mastodon/components/autosuggest/utils.ts  |  79 +++++-
 .../features/compose/redesign/selectors.ts    |   9 +
 .../compose/redesign/styles.module.scss       |  39 ++-
 .../features/compose/redesign/textarea.tsx    | 154 ++++++------
 10 files changed, 853 insertions(+), 85 deletions(-)
 create mode 100644 app/javascript/mastodon/components/autosuggest/autosuggest.stories.tsx
 create mode 100644 app/javascript/mastodon/components/autosuggest/hooks.tsx
 create mode 100644 app/javascript/mastodon/components/autosuggest/items.tsx
 create mode 100644 app/javascript/mastodon/components/autosuggest/list.tsx
 create mode 100644 app/javascript/mastodon/components/autosuggest/styles.module.scss
 create mode 100644 app/javascript/mastodon/components/autosuggest/types.ts

diff --git a/app/javascript/mastodon/components/autosuggest/autosuggest.stories.tsx b/app/javascript/mastodon/components/autosuggest/autosuggest.stories.tsx
new file mode 100644
index 00000000000..f2d47bfb0d0
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/autosuggest.stories.tsx
@@ -0,0 +1,119 @@
+import { useRef, useState } from 'react';
+
+import type { Meta, StoryObj } from '@storybook/react-vite';
+import { fn } from 'storybook/test';
+
+import { accountFactoryImmutable } from '@/testing/factories';
+
+import { TextArea } from '../form_fields';
+import menuClasses from '../menu/styles.module.scss';
+
+import { useAutosuggestMenu } from './hooks';
+import { AutosuggestItem } from './items';
+import { AutosuggestMenu } from './list';
+import type {
+  AccountSuggestion,
+  EmojiSuggestion,
+  HashtagSuggestion,
+  Suggestion,
+} from './types';
+
+type SuggestTypes = Suggestion['type'];
+
+const suggestionsMap = {
+  account: [{ type: 'account', id: '1' }] satisfies AccountSuggestion[],
+  emoji: [
+    { type: 'emoji', id: '+1', native: '👍' },
+    { type: 'emoji', id: '-1', native: '👎' },
+    { type: 'emoji', id: 'smile', native: '🙂' },
+  ] satisfies EmojiSuggestion[],
+  hashtag: [
+    { type: 'hashtag', name: 'Testing', id: '1', totalUses: 0 },
+    { type: 'hashtag', name: 'Test', id: '2', totalUses: 10 },
+  ] satisfies HashtagSuggestion[],
+} satisfies Record<SuggestTypes, Suggestion[]>;
+
+const fetchCb = fn().mockName('fetching token');
+const selectCb = fn().mockName('selected item');
+const clearCb = fn().mockName('cleared suggestions');
+
+const meta = {
+  title: 'Redesign/Autosuggest',
+  render() {
+    const [suggestions, setSuggestions] = useState<Suggestion[]>([]);
+    const textareaRef = useRef<HTMLTextAreaElement>(null);
+
+    const { onTextChange, suggestProps, sourceProps } = useAutosuggestMenu({
+      suggestions,
+      onSelect: selectCb,
+      onFetch(token) {
+        const newSuggestions = tokenToSuggestions(token);
+
+        fetchCb(token, newSuggestions);
+        setSuggestions(newSuggestions);
+      },
+      onClear() {
+        clearCb();
+        setSuggestions([]);
+      },
+    });
+
+    return (
+      <div>
+        <TextArea {...sourceProps} onChange={onTextChange} ref={textareaRef} />
+        <AutosuggestMenu
+          {...suggestProps}
+          reference={textareaRef.current}
+          maxWidth={200}
+        />
+      </div>
+    );
+  },
+  parameters: {
+    state: {
+      accounts: {
+        '1': accountFactoryImmutable(),
+      },
+    },
+    redesign: true,
+  },
+} satisfies Meta;
+
+function tokenToSuggestions(token: string) {
+  let suggestions: Suggestion[] = [];
+  switch (token.charAt(0)) {
+    case '@':
+      suggestions = suggestionsMap.account;
+      break;
+    case ':':
+      suggestions = suggestionsMap.emoji;
+      break;
+    case '#':
+      suggestions = suggestionsMap.hashtag;
+  }
+  return suggestions;
+}
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+export const Textarea: Story = {};
+
+export const Static: Story = {
+  render() {
+    return (
+      <div className={menuClasses.card} style={{ width: '300px' }}>
+        {Object.values(suggestionsMap)
+          .flat()
+          .map((suggestion) => (
+            <AutosuggestItem
+              suggestion={suggestion}
+              key={suggestion.id}
+              className={menuClasses.item}
+            />
+          ))}
+      </div>
+    );
+  },
+};
diff --git a/app/javascript/mastodon/components/autosuggest/hooks.tsx b/app/javascript/mastodon/components/autosuggest/hooks.tsx
new file mode 100644
index 00000000000..fa9f9bba19d
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/hooks.tsx
@@ -0,0 +1,233 @@
+import { useCallback, useRef, useState } from 'react';
+
+import classNames from 'classnames';
+
+import type { Simplify } from 'type-fest';
+import { useThrottledCallback } from 'use-debounce';
+
+import { getAllMenuItems } from '../menu';
+
+import type { AutosuggestMenuProps } from './list';
+import classes from './styles.module.scss';
+import type { AutosuggestSourceElements, Source, Suggestion } from './types';
+import { sourceToElement, textAtCursorMatchesToken } from './utils';
+
+export type OnSuggestionSelect = (
+  start: number,
+  token: string,
+  suggestion: Suggestion,
+) => void;
+
+interface UseAutosuggestMenuOptions {
+  suggestions: Suggestion[];
+  onSelect: OnSuggestionSelect;
+  onFetch?: (token: string) => void;
+  onClear?: () => void;
+}
+
+type SourceProps = React.DetailedHTMLProps<
+  React.HTMLAttributes<AutosuggestSourceElements>,
+  AutosuggestSourceElements
+>;
+
+interface UseAutosuggestReturn {
+  onTextChange: React.ChangeEventHandler<AutosuggestSourceElements>;
+  focus: (event?: React.SyntheticEvent) => void;
+  getToken: () => { token: string | null; startPosition: number };
+
+  mirror?: React.JSX.Element;
+
+  suggestProps: Simplify<Omit<AutosuggestMenuProps, 'children'>>;
+
+  sourceProps: Simplify<
+    Pick<SourceProps, 'onSelect' | 'onScroll' | 'aria-autocomplete'>
+  >;
+}
+
+export function useAutosuggestMenu({
+  suggestions,
+  onSelect,
+  onFetch,
+  onClear,
+}: UseAutosuggestMenuOptions): UseAutosuggestReturn {
+  const lastTokenRef = useRef<string | null>(null); // The last suggestion token encountered.
+  const tokenStartRef = useRef(0); // Character location of the token start.
+  const listRef = useRef<HTMLDivElement>(null);
+
+  const onTextChange: React.ChangeEventHandler<AutosuggestSourceElements> =
+    useCallback(
+      (event) => {
+        // Detect a token, and if so fetch suggestions, or dismiss them if not.
+        const [tokenStart, token] = textAtCursorMatchesToken(
+          event.target.value,
+          event.target.selectionStart ?? 0,
+          ['@', '＠', ':', '#', '＃'],
+        );
+
+        if (token !== null && lastTokenRef.current !== token) {
+          tokenStartRef.current = tokenStart;
+          lastTokenRef.current = token;
+          onFetch?.(token);
+        } else if (token === null) {
+          lastTokenRef.current = null;
+          onClear?.();
+        }
+      },
+      [onClear, onFetch],
+    );
+
+  const focus = useCallback(
+    (event?: React.SyntheticEvent) => {
+      if (suggestions.length > 0 && listRef.current) {
+        event?.preventDefault();
+        (getAllMenuItems(listRef.current).at(0) ?? listRef.current).focus();
+      }
+    },
+    [suggestions.length],
+  );
+
+  const getToken = useCallback(
+    () => ({
+      token: lastTokenRef.current,
+      startPosition: tokenStartRef.current,
+    }),
+    [],
+  );
+  const tokenCb = useCallback(() => lastTokenRef.current, []);
+
+  const onSuggestionClick: React.MouseEventHandler<HTMLButtonElement> =
+    useCallback(
+      (event) => {
+        const { id, index, type } = event.currentTarget.dataset;
+        const suggestion = suggestions.find((suggestion, i) =>
+          suggestion.type === type && suggestion.id
+            ? suggestion.id === id
+            : index && Number.parseInt(index) === i,
+        );
+        if (!suggestion || !lastTokenRef.current) {
+          return;
+        }
+
+        onSelect(tokenStartRef.current, lastTokenRef.current, suggestion);
+      },
+      [onSelect, suggestions],
+    );
+
+  return {
+    // Used by the parent.
+    onTextChange,
+    focus,
+    getToken,
+
+    // For the component below.
+    suggestProps: {
+      suggestions,
+      onSuggestionClick,
+      listRef,
+      tokenCb,
+    } satisfies AutosuggestMenuProps,
+
+    sourceProps: {
+      'aria-autocomplete': 'list',
+    } satisfies SourceProps,
+  };
+}
+
+interface UseAutosuggestFloatingMenuOptions extends UseAutosuggestMenuOptions {
+  text?: string;
+  sourceRef: Source;
+  className?: string;
+}
+
+export function useAutosuggestFloatingMenu({
+  text,
+  sourceRef,
+  className,
+  ...suggestOptions
+}: UseAutosuggestFloatingMenuOptions): UseAutosuggestReturn {
+  const [mirrorElement, setMirrorElement] = useState<HTMLElement | null>(null); // Reference to the mirror element.
+  const [selectedText, setSelectedText] = useState(text ?? ''); // The actual selected text inside the mirror.
+  const updatePopover = useRef<() => void>(null); // Reference to the popover update callback.
+
+  const { getToken, ...autosuggestProps } = useAutosuggestMenu(suggestOptions);
+
+  const { onClear } = suggestOptions;
+
+  const source = sourceToElement(sourceRef);
+
+  // Update the popover on scroll or select.
+  const onUpdate = useCallback(() => {
+    // Call the popover update callback. This enables the popover to adjust position with scroll.
+    updatePopover.current?.();
+
+    if (source && mirrorElement) {
+      // Set top to scroll offset so bottom edge looks right.
+      mirrorElement.style.setProperty('top', `${-1 * source.scrollTop}px`);
+
+      const { height } = source.getBoundingClientRect();
+      const offset = mirrorElement.offsetHeight - source.scrollTop;
+      if (offset < 0 || offset > height) {
+        onClear?.();
+      }
+    }
+  }, [mirrorElement, onClear, source, updatePopover]);
+
+  // When the caret or selection changes, update the selected text and clear the composer if it doesn't include a token.
+  const onSelect: React.ReactEventHandler<AutosuggestSourceElements> =
+    useCallback(
+      (event) => {
+        const { token, startPosition } = getToken();
+        if (token === null) {
+          return;
+        }
+
+        onUpdate();
+
+        const { selectionStart: rawStart, value } = event.currentTarget;
+        const selectionStart = rawStart ?? 0;
+        const tokenEnd = startPosition + token.length;
+        setSelectedText(value.slice(0, tokenEnd)); // Only set the text up to the selected end point.
+
+        if (selectionStart < startPosition || selectionStart > tokenEnd) {
+          onClear?.();
+        }
+      },
+      [getToken, onClear, onUpdate],
+    );
+
+  const onScroll = useThrottledCallback(onUpdate, 0);
+  const updatePopoverCb = useCallback((update: () => void) => {
+    updatePopover.current = () => update;
+  }, []);
+
+  const mirror = (
+    <div
+      className={classNames(
+        classes.mirror,
+        source instanceof HTMLTextAreaElement && classes.textAreaMirror,
+        className,
+      )}
+      ref={setMirrorElement}
+    >
+      {selectedText}
+    </div>
+  );
+
+  return {
+    mirror,
+    getToken,
+    ...autosuggestProps,
+
+    sourceProps: {
+      ...autosuggestProps.sourceProps,
+      onScroll,
+      onSelect,
+    } satisfies SourceProps,
+
+    suggestProps: {
+      ...autosuggestProps.suggestProps,
+      reference: mirrorElement,
+      updatePopoverCb,
+    } satisfies AutosuggestMenuProps,
+  };
+}
diff --git a/app/javascript/mastodon/components/autosuggest/items.tsx b/app/javascript/mastodon/components/autosuggest/items.tsx
new file mode 100644
index 00000000000..1e293f0454d
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/items.tsx
@@ -0,0 +1,97 @@
+import type React from 'react';
+
+import classNames from 'classnames';
+
+import { selectPlainAccount } from '@/mastodon/selectors/accounts';
+import { useAppSelector } from '@/mastodon/store';
+
+import { Avatar } from '../avatar';
+import { DisplayName } from '../display_name';
+import { Emoji } from '../emoji';
+import { MenuItem } from '../menu';
+import { ShortNumber } from '../short_number';
+
+import classes from './styles.module.scss';
+import type {
+  EmojiSuggestion,
+  HashtagSuggestion,
+  LocalHashtagSuggestion,
+  Suggestion,
+} from './types';
+
+export const AutosuggestItem: React.FC<
+  {
+    suggestion: Suggestion;
+    className?: string;
+  } & React.ComponentPropsWithoutRef<'button'>
+> = ({ suggestion, className, ...props }) => {
+  let suggestComp: React.ReactNode = null;
+  if (suggestion.type === 'account') {
+    suggestComp = <AutosuggestAccount {...suggestion} />;
+  } else if (suggestion.type === 'hashtag') {
+    suggestComp = <AutosuggestHashtag {...suggestion} />;
+  } else {
+    suggestComp = <AutosuggestEmoji {...suggestion} />;
+  }
+
+  return (
+    <MenuItem
+      {...props}
+      className={classNames(classes.item, className)}
+      data-id={suggestion.id}
+      data-type={suggestion.type}
+    >
+      {suggestComp}
+    </MenuItem>
+  );
+};
+
+const AutosuggestAccount: React.FC<{ id: string }> = ({ id }) => {
+  const account = useAppSelector((state) => selectPlainAccount(state, id));
+
+  if (!account) {
+    return null;
+  }
+
+  return (
+    <>
+      <Avatar account={account} className={classes.itemIcon} size={32} />
+      <div>
+        <DisplayName
+          account={account}
+          variant='noDomain'
+          className={classes.itemAccountName}
+        />
+        <span className={classes.itemAccountHandle}>{account.acct}</span>
+      </div>
+    </>
+  );
+};
+
+const AutosuggestEmoji: React.FC<EmojiSuggestion> = ({ id, native }) => {
+  const colons = `:${id}:`;
+  return (
+    <>
+      <span className={classes.itemIcon}>
+        <Emoji code={native ?? colons} />
+      </span>
+
+      <span>{colons}</span>
+    </>
+  );
+};
+
+const AutosuggestHashtag: React.FC<
+  HashtagSuggestion | LocalHashtagSuggestion
+> = ({ name, ...props }) => {
+  return (
+    <>
+      #{name}
+      {'totalUses' in props ? (
+        <span className={classes.itemHashUses}>
+          <ShortNumber value={props.totalUses} />
+        </span>
+      ) : null}{' '}
+    </>
+  );
+};
diff --git a/app/javascript/mastodon/components/autosuggest/list.tsx b/app/javascript/mastodon/components/autosuggest/list.tsx
new file mode 100644
index 00000000000..6c3d03592e3
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/list.tsx
@@ -0,0 +1,114 @@
+import { useEffect } from 'react';
+
+import classNames from 'classnames';
+
+import { useMergedRefs } from '@/mastodon/hooks/useMergedRefs';
+import { usePrevious } from '@/mastodon/hooks/usePrevious';
+
+import { LocalCustomEmojiProvider } from '../emoji/context';
+import { Menu, useMenuContext } from '../menu';
+import { MenuCard } from '../menu/card';
+import { Popover } from '../popover';
+
+import { AutosuggestItem } from './items';
+import classes from './styles.module.scss';
+import type { Suggestion } from './types';
+
+export interface AutosuggestMenuProps {
+  suggestions: Suggestion[];
+  tokenCb: () => string | null;
+  onSuggestionClick: React.MouseEventHandler;
+  children?: React.ReactNode;
+  listRef?: React.Ref<HTMLDivElement>;
+  reference?: HTMLElement | null;
+  updatePopoverCb?: (update: () => void) => void;
+  maxWidth?: number | string;
+}
+
+export const AutosuggestMenu: React.FC<AutosuggestMenuProps> = ({
+  suggestions,
+  onSuggestionClick,
+  children,
+  ...menuProps
+}) => {
+  return (
+    <Menu noFocus>
+      {suggestions.length > 0 && (
+        <AutosuggestMenuList {...menuProps} suggestions={suggestions}>
+          {children ??
+            suggestions.map((suggestion, index) => (
+              <AutosuggestItem
+                key={`${suggestion.type}:${suggestion.id}`}
+                onClick={onSuggestionClick}
+                suggestion={suggestion}
+                data-index={index}
+              />
+            ))}
+        </AutosuggestMenuList>
+      )}
+    </Menu>
+  );
+};
+
+type AutosuggestMenuListProps = Omit<
+  AutosuggestMenuProps,
+  'onSuggestionClick'
+> & {
+  children: React.ReactNode;
+};
+
+const AutosuggestMenuList: React.FC<AutosuggestMenuListProps> = ({
+  children,
+  listRef,
+  tokenCb,
+  suggestions,
+  reference,
+  updatePopoverCb,
+  maxWidth,
+}) => {
+  const token = tokenCb();
+  const lastToken = usePrevious(token);
+
+  const { popover, menuListProps } = useMenuContext();
+
+  useEffect(() => {
+    if (!popover.isMenuOpen && token !== lastToken && suggestions.length > 0) {
+      popover.openMenu();
+    }
+  }, [lastToken, popover, suggestions.length, token]);
+
+  const mergedRef = useMergedRefs(menuListProps.ref, listRef);
+
+  return (
+    <Popover
+      isOpen={popover.isMenuOpen}
+      onClose={popover.closeMenu}
+      reference={reference ?? null}
+      popoverElement={popover.popover}
+      container={null}
+      placement='bottom-start'
+    >
+      {({ props: popoverChildProps, update }) => {
+        updatePopoverCb?.(update);
+
+        return (
+          <MenuCard
+            {...popoverChildProps}
+            {...menuListProps}
+            style={
+              {
+                '--_max-card-width':
+                  typeof maxWidth === 'number' ? `${maxWidth}px` : maxWidth,
+                ...popoverChildProps.style,
+              } as React.CSSProperties
+            }
+            ref={mergedRef}
+            className={classNames(maxWidth && classes.menuWidth)}
+          >
+            <LocalCustomEmojiProvider>{children}</LocalCustomEmojiProvider>
+          </MenuCard>
+        );
+      }}
+    </Popover>
+  );
+};
diff --git a/app/javascript/mastodon/components/autosuggest/styles.module.scss b/app/javascript/mastodon/components/autosuggest/styles.module.scss
new file mode 100644
index 00000000000..81a78d46de3
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/styles.module.scss
@@ -0,0 +1,59 @@
+@use '@/styles/mastodon/mixins';
+
+.mirror {
+  visibility: hidden;
+  pointer-events: none;
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+}
+
+.textAreaMirror {
+  white-space: pre-wrap; // This makes the formatting match the text area.
+}
+
+.debug.mirror {
+  visibility: visible;
+  opacity: 0.2;
+  background-color: red;
+  color: white;
+}
+
+.menuWidth {
+  width: 100%;
+  max-width: var(--_max-card-width);
+}
+
+.item {
+  display: flex;
+  gap: var(--space-xs);
+  min-height: var(--space-3xl);
+}
+
+.itemIcon {
+  width: var(--space-3xl);
+  height: var(--space-3xl);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  border-radius: var(--radius-round);
+  overflow: hidden;
+  background-color: var(--color-bg-highlight);
+}
+
+.itemHashUses {
+  color: var(--color-text-tertiary);
+  margin-inline-start: auto;
+  font-size: var(--fs-xs);
+}
+
+.itemAccountName {
+  @include mixins.type-label-lg;
+}
+
+.itemAccountHandle {
+  @include mixins.type-label-sm;
+
+  color: var(--color-text-tertiary);
+}
diff --git a/app/javascript/mastodon/components/autosuggest/types.ts b/app/javascript/mastodon/components/autosuggest/types.ts
new file mode 100644
index 00000000000..befdb5b766e
--- /dev/null
+++ b/app/javascript/mastodon/components/autosuggest/types.ts
@@ -0,0 +1,35 @@
+export interface AccountSuggestion {
+  type: 'account';
+  id: string;
+}
+export interface EmojiSuggestion {
+  type: 'emoji';
+  id: string;
+  custom?: boolean;
+  native?: string;
+  imageUrl?: string;
+}
+export interface LocalHashtagSuggestion {
+  type: 'hashtag';
+  id?: string;
+  name: string;
+}
+export interface HashtagSuggestion {
+  type: 'hashtag';
+  id: string;
+  name: string;
+  totalUses: number;
+}
+
+export type Suggestion =
+  | AccountSuggestion
+  | EmojiSuggestion
+  | LocalHashtagSuggestion
+  | HashtagSuggestion;
+
+export type AutosuggestSourceElements = HTMLInputElement | HTMLTextAreaElement;
+
+export type Source =
+  | React.RefObject<AutosuggestSourceElements | null>
+  | AutosuggestSourceElements
+  | null;
diff --git a/app/javascript/mastodon/components/autosuggest/utils.ts b/app/javascript/mastodon/components/autosuggest/utils.ts
index 5744a773017..9899017a2d3 100644
--- a/app/javascript/mastodon/components/autosuggest/utils.ts
+++ b/app/javascript/mastodon/components/autosuggest/utils.ts
@@ -1,10 +1,15 @@
+import { isRecordObject } from '@/mastodon/utils/objects';
+import { stringOrUndefined } from '@/mastodon/utils/strings';
+
 import { WORD } from '../../utils/hashtags';
 
-export const textAtCursorMatchesToken = (
+import type { Source, Suggestion } from './types';
+
+export function textAtCursorMatchesToken(
   str: string,
   caretPosition: number,
   searchTokens: string[],
-) => {
+) {
   let word: string;
 
   const regex = new RegExp(
@@ -31,4 +36,72 @@ export const textAtCursorMatchesToken = (
   } else {
     return [null, null] as const;
   }
-};
+}
+
+export function immutableListToSuggestions(list: Immutable.List<unknown>) {
+  const suggestions: Suggestion[] = [];
+  const hashtagSet = new Set<string>();
+
+  let fakeId = 0;
+
+  for (const suggestion of list.toArray()) {
+    if (!isRecordObject(suggestion)) {
+      continue;
+    }
+    const type = suggestion.type;
+    const id = stringOrUndefined(suggestion.id) ?? `fake-${fakeId++}`; // Fake ID so we don't have React key issues.
+
+    switch (type) {
+      case 'account':
+        suggestions.push({
+          type,
+          id,
+        });
+        break;
+      case 'emoji':
+        suggestions.push({
+          type,
+          id,
+          custom: !!suggestion.custom,
+          native: stringOrUndefined(suggestion.native),
+          imageUrl: stringOrUndefined(suggestion.imageUrl),
+        });
+        break;
+      case 'hashtag': {
+        const name = stringOrUndefined(suggestion.name);
+        if (!name || hashtagSet.has(name)) {
+          continue;
+        }
+
+        hashtagSet.add(name);
+
+        suggestions.push({
+          type,
+          name,
+          id,
+          totalUses: tagHistoryToUses(suggestion.history),
+        });
+      }
+    }
+  }
+
+  return suggestions;
+}
+
+export function tagHistoryToUses(history: unknown) {
+  if (!Array.isArray(history)) {
+    return 0;
+  }
+
+  return history.reduce<number>(
+    (total, current) =>
+      isRecordObject(current) && typeof current.uses === 'number'
+        ? total + current.uses
+        : total,
+    0,
+  );
+}
+
+export function sourceToElement(source: Source) {
+  return !source || source instanceof HTMLElement ? source : source.current;
+}
diff --git a/app/javascript/mastodon/features/compose/redesign/selectors.ts b/app/javascript/mastodon/features/compose/redesign/selectors.ts
index 8fe1f23e4d3..0b9f6da112f 100644
--- a/app/javascript/mastodon/features/compose/redesign/selectors.ts
+++ b/app/javascript/mastodon/features/compose/redesign/selectors.ts
@@ -1,6 +1,7 @@
 import { length } from 'stringz';
 
 import type { ApiMediaAttachmentJSON } from '@/mastodon/api_types/media_attachments';
+import { immutableListToSuggestions } from '@/mastodon/components/autosuggest/utils';
 import type { StatusVisibility } from '@/mastodon/models/status';
 import type { ComposeType } from '@/mastodon/reducers/slices/composer';
 import { createAppSelector } from '@/mastodon/store';
@@ -239,3 +240,11 @@ export const selectComposePoll = createAppSelector(
     };
   },
 );
+
+export const selectSuggestions = createAppSelector(
+  [
+    (state) =>
+      state.compose.get('suggestions') as unknown as Immutable.List<unknown>,
+  ],
+  (list) => immutableListToSuggestions(list),
+);
diff --git a/app/javascript/mastodon/features/compose/redesign/styles.module.scss b/app/javascript/mastodon/features/compose/redesign/styles.module.scss
index fd31930eec3..90c3299b1d2 100644
--- a/app/javascript/mastodon/features/compose/redesign/styles.module.scss
+++ b/app/javascript/mastodon/features/compose/redesign/styles.module.scss
@@ -114,27 +114,50 @@
 
 .textareaWrapper {
   flex-grow: 1;
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.textarea,
+.textareaMirror {
+  @include mixins.type-body-lg;
+
   padding: var(--space-xs);
+}
+
+.textarea {
+  flex-grow: 1;
   border-radius: var(--radius-xs);
   transition: border 200ms;
   cursor: text;
+  border: none;
+  width: 100%;
+  outline: none;
 
-  &:focus-within {
+  &:focus {
     outline: 2px solid var(--color-border-brand);
     outline-offset: -2px;
 
-    textarea::placeholder {
+    &::placeholder {
       color: transparent;
     }
   }
+}
 
-  textarea {
-    @include mixins.type-body-lg;
+textarea.textarea {
+  resize: none;
+}
 
-    border: none;
-    width: 100%;
-    outline: none;
-  }
+.textareaMirror {
+  visibility: hidden;
+  pointer-events: none;
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  white-space: pre-wrap; // This makes the formatting match the text area.
 }
 
 .attachments {
diff --git a/app/javascript/mastodon/features/compose/redesign/textarea.tsx b/app/javascript/mastodon/features/compose/redesign/textarea.tsx
index 58240fe154e..c960da0d322 100644
--- a/app/javascript/mastodon/features/compose/redesign/textarea.tsx
+++ b/app/javascript/mastodon/features/compose/redesign/textarea.tsx
@@ -1,12 +1,9 @@
-import type React from 'react';
 import { useCallback, useRef } from 'react';
 
 import { defineMessages, useIntl } from 'react-intl';
 
 import classNames from 'classnames';
 
-import type { TextareaAutosizeProps } from 'react-textarea-autosize';
-
 import {
   changeCompose,
   fetchComposeSuggestions,
@@ -14,15 +11,22 @@ import {
   selectComposeSuggestion,
 } from '@/mastodon/actions/compose';
 import { processPasteOrDrop } from '@/mastodon/actions/compose_typed';
-import AutosuggestTextareaOriginal from '@/mastodon/components/autosuggest_textarea';
-import { COMPOSER_TEXTAREA_ID } from '@/mastodon/reducers/slices/composer';
+import type { OnSuggestionSelect } from '@/mastodon/components/autosuggest/hooks';
+import { useAutosuggestFloatingMenu } from '@/mastodon/components/autosuggest/hooks';
+import { AutosuggestMenu } from '@/mastodon/components/autosuggest/list';
+import { TextArea } from '@/mastodon/components/form_fields';
+import { normalizeKey } from '@/mastodon/components/hotkeys/utils';
+import {
+  COMPOSER_TEXTAREA_ID,
+  focusComposerTextarea,
+} from '@/mastodon/reducers/slices/composer';
 import {
   createAppSelector,
   useAppDispatch,
   useAppSelector,
 } from '@/mastodon/store';
 
-import { selectComposeType } from './selectors';
+import { selectComposeType, selectSuggestions } from './selectors';
 import classes from './styles.module.scss';
 
 const messages = defineMessages({
@@ -38,25 +42,8 @@ const messages = defineMessages({
   },
 });
 
-type SuggestSelectedHandler = (
-  position: number,
-  token: string,
-  suggestion: unknown,
-) => void;
-
-const AutosuggestTextarea =
-  AutosuggestTextareaOriginal as React.ForwardRefExoticComponent<
-    {
-      suggestions: Immutable.List<unknown>;
-      onSuggestionSelected: SuggestSelectedHandler;
-      onSuggestionsClearRequested: () => void;
-      onSuggestionsFetchRequested: (token: string) => void;
-    } & TextareaAutosizeProps &
-      React.RefAttributes<HTMLTextAreaElement>
-  >;
-
 type ComposeTextareaProps = Omit<
-  TextareaAutosizeProps,
+  React.ComponentPropsWithoutRef<'textarea'>,
   | 'placeholder'
   | 'onFocus'
   | 'onBlur'
@@ -71,9 +58,6 @@ const selectComposeTextState = createAppSelector(
   (compose) => ({
     text: compose.get('text') as string,
     lang: compose.get('language') as string,
-    suggestions: compose.get(
-      'suggestions',
-    ) as unknown as Immutable.List<unknown>,
     isSubmitting: !!compose.get('is_submitting'),
   }),
 );
@@ -86,38 +70,78 @@ export const ComposeTextarea: React.FC<ComposeTextareaProps> = ({
 }) => {
   const intl = useIntl();
 
+  // Selectors
   const type = useAppSelector(selectComposeType);
-  const { suggestions, text, lang, isSubmitting } = useAppSelector(
-    selectComposeTextState,
-  );
-
+  const { text, lang, isSubmitting } = useAppSelector(selectComposeTextState);
   const dispatch = useAppDispatch();
-  const onClickWrapper: React.MouseEventHandler<HTMLDivElement> = useCallback(
-    (event) => {
-      if (event.target instanceof HTMLDivElement) {
-        event.target.querySelector('textarea')?.focus();
-      }
-    },
-    [],
-  );
-  const onChange: React.ChangeEventHandler<HTMLTextAreaElement> = useCallback(
-    (event) => {
-      dispatch(changeCompose(event.target.value));
+
+  // Suggestion logic
+  const onSuggestionFetch = useCallback(
+    (token: string) => {
+      dispatch(fetchComposeSuggestions(token));
     },
     [dispatch],
   );
+
+  const onSuggestion: OnSuggestionSelect = useCallback(
+    (tokenStart, token, suggestion) => {
+      dispatch(
+        selectComposeSuggestion(tokenStart, token, suggestion, ['text']),
+      );
+      focusComposerTextarea(true);
+    },
+    [dispatch],
+  );
+
+  const onSuggestionClear = useCallback(() => {
+    dispatch(clearComposeSuggestions());
+  }, [dispatch]);
+
+  const suggestions = useAppSelector(selectSuggestions);
+  const textAreaRef = useRef<HTMLTextAreaElement>(null);
+
+  const { onTextChange, focus, mirror, sourceProps, suggestProps } =
+    useAutosuggestFloatingMenu({
+      suggestions,
+      text,
+      className: classes.textareaMirror,
+      sourceRef: textAreaRef,
+      onSelect: onSuggestion,
+      onFetch: onSuggestionFetch,
+      onClear: onSuggestionClear,
+    });
+
+  // Update the composer text and trigger suggestions.
+  const onChange: React.ChangeEventHandler<HTMLTextAreaElement> = useCallback(
+    (event) => {
+      dispatch(changeCompose(event.target.value));
+      onTextChange(event);
+    },
+    [dispatch, onTextChange],
+  );
+
   const onKeyDown: React.KeyboardEventHandler<HTMLTextAreaElement> =
     useCallback(
       (event) => {
-        const key = event.key.toLowerCase();
+        const key = normalizeKey(event.key);
+
         if (key === 'enter' && (event.ctrlKey || event.metaKey)) {
           onSubmit();
           event.preventDefault();
-        } else if (['esc', 'escape'].includes(key)) {
-          event.currentTarget.blur();
+          onSuggestionClear();
+        } else if (key === 'escape') {
+          // Dismiss the suggestions if we're displaying any.
+          if (suggestions.length > 0) {
+            onSuggestionClear();
+          } else {
+            // Otherwise lose focus on the textarea.
+            event.currentTarget.blur();
+          }
+        } else if (key === 'down') {
+          focus(event);
         }
       },
-      [onSubmit],
+      [onSubmit, onSuggestionClear, suggestions.length, focus],
     );
 
   const onPasteOrDrop = useCallback(
@@ -131,34 +155,15 @@ export const ComposeTextarea: React.FC<ComposeTextareaProps> = ({
     },
     [dispatch],
   );
-  const onSuggestionsFetchRequested = useCallback(
-    (token: string) => {
-      dispatch(fetchComposeSuggestions(token));
-    },
-    [dispatch],
-  );
-  const onSuggestionsClearRequested = useCallback(() => {
-    dispatch(clearComposeSuggestions());
-  }, [dispatch]);
-  const onSuggestionSelected: SuggestSelectedHandler = useCallback(
-    (position, token, suggestion) => {
-      dispatch(selectComposeSuggestion(position, token, suggestion, ['text']));
-    },
-    [dispatch],
-  );
-
-  const textareaRef = useRef<HTMLTextAreaElement>(null);
 
   return (
-    // eslint-disable-next-line jsx-a11y/click-events-have-key-events, jsx-a11y/no-static-element-interactions -- This just moves focus to the textarea.
-    <div
-      onClick={onClickWrapper}
-      className={classNames(className, classes.textareaWrapper)}
-    >
-      <AutosuggestTextarea
+    <div className={classes.textareaWrapper}>
+      <TextArea
         {...props}
+        dir='auto'
         id={COMPOSER_TEXTAREA_ID}
-        ref={textareaRef}
+        className={classNames(className, classes.textarea)}
+        ref={textAreaRef}
         value={text}
         lang={lang}
         placeholder={intl.formatMessage(
@@ -167,15 +172,16 @@ export const ComposeTextarea: React.FC<ComposeTextareaProps> = ({
             : messages.placeholder,
         )}
         disabled={disabled || isSubmitting}
-        suggestions={suggestions}
-        onSuggestionsFetchRequested={onSuggestionsFetchRequested}
-        onSuggestionsClearRequested={onSuggestionsClearRequested}
-        onSuggestionSelected={onSuggestionSelected}
         onKeyDown={onKeyDown}
         onDrop={onPasteOrDrop}
         onPaste={onPasteOrDrop}
         onChange={onChange}
+        {...sourceProps}
       />
+
+      {mirror}
+
+      <AutosuggestMenu {...suggestProps} maxWidth={280} />
     </div>
   );
 };