♻️ refactor: Replace fontSize Recoil atom with Jotai (#10171)

* fix: reapply chat font size on load

* refactor: streamline font size handling in localStorage

* fix: update matchMedia mock to accurately reflect desktop and touchscreen capabilities

* refactor: implement Jotai for font size management and initialize on app load

- Replaced Recoil with Jotai for font size state management across components.
- Added a new `fontSize` atom to handle font size changes and persist them in localStorage.
- Implemented `initializeFontSize` function to apply saved font size on app load.
- Updated relevant components to utilize the new font size atom.

---------

Co-authored-by: ddooochii <ddooochii@gmail.com>
Co-authored-by: Danny Avila <danny@librechat.ai>

client/src/App.jsx

@@ -1,3 +1,4 @@
+import { useEffect } from 'react';
 import { RecoilRoot } from 'recoil';
 import { DndProvider } from 'react-dnd';
 import { RouterProvider } from 'react-router-dom';
@@ -8,6 +9,7 @@ import { Toast, ThemeProvider, ToastProvider } from '@librechat/client';
 import { QueryClient, QueryClientProvider, QueryCache } from '@tanstack/react-query';
 import { ScreenshotProvider, useApiErrorBoundary } from './hooks';
 import { getThemeFromEnv } from './utils/getThemeFromEnv';
+import { initializeFontSize } from '~/store/fontSize';
 import { LiveAnnouncer } from '~/a11y';
 import { router } from './routes';
 
@@ -24,6 +26,10 @@ const App = () => {
     }),
   });
 
+  useEffect(() => {
+    initializeFontSize();
+  }, []);
+
   // Load theme from environment variables if available
   const envTheme = getThemeFromEnv();
 

client/src/components/Chat/Messages/MessageParts.tsx

@@ -1,10 +1,12 @@
 import React, { useMemo } from 'react';
+import { useAtomValue } from 'jotai';
 import { useRecoilValue } from 'recoil';
 import type { TMessageContentParts } from 'librechat-data-provider';
 import type { TMessageProps, TMessageIcon } from '~/common';
 import { useMessageHelpers, useLocalize, useAttachments } from '~/hooks';
 import MessageIcon from '~/components/Chat/Messages/MessageIcon';
 import ContentParts from './Content/ContentParts';
+import { fontSizeAtom } from '~/store/fontSize';
 import SiblingSwitch from './SiblingSwitch';
 import MultiMessage from './MultiMessage';
 import HoverButtons from './HoverButtons';
@@ -36,7 +38,7 @@ export default function Message(props: TMessageProps) {
     regenerateMessage,
   } = useMessageHelpers(props);
 
-  const fontSize = useRecoilValue(store.fontSize);
+  const fontSize = useAtomValue(fontSizeAtom);
   const maximizeChatSpace = useRecoilValue(store.maximizeChatSpace);
   const { children, messageId = null, isCreatedByUser } = message ?? {};
 

client/src/components/Chat/Messages/MessagesView.tsx

@@ -1,10 +1,12 @@
 import { useState } from 'react';
+import { useAtomValue } from 'jotai';
 import { useRecoilValue } from 'recoil';
 import { CSSTransition } from 'react-transition-group';
 import type { TMessage } from 'librechat-data-provider';
 import { useScreenshot, useMessageScrolling, useLocalize } from '~/hooks';
 import ScrollToBottom from '~/components/Messages/ScrollToBottom';
 import { MessagesViewProvider } from '~/Providers';
+import { fontSizeAtom } from '~/store/fontSize';
 import MultiMessage from './MultiMessage';
 import { cn } from '~/utils';
 import store from '~/store';
@@ -15,7 +17,7 @@ function MessagesViewContent({
   messagesTree?: TMessage[] | null;
 }) {
   const localize = useLocalize();
-  const fontSize = useRecoilValue(store.fontSize);
+  const fontSize = useAtomValue(fontSizeAtom);
   const { screenshotTargetRef } = useScreenshot();
   const scrollButtonPreference = useRecoilValue(store.showScrollButton);
   const [currentEditId, setCurrentEditId] = useState<number | string | null>(-1);

client/src/components/Chat/Messages/SearchMessage.tsx

@@ -1,10 +1,12 @@
 import { useMemo } from 'react';
+import { useAtomValue } from 'jotai';
 import { useRecoilValue } from 'recoil';
 import { useAuthContext, useLocalize } from '~/hooks';
 import type { TMessageProps, TMessageIcon } from '~/common';
 import MinimalHoverButtons from '~/components/Chat/Messages/MinimalHoverButtons';
 import Icon from '~/components/Chat/Messages/MessageIcon';
 import SearchContent from './Content/SearchContent';
+import { fontSizeAtom } from '~/store/fontSize';
 import SearchButtons from './SearchButtons';
 import SubRow from './SubRow';
 import { cn } from '~/utils';
@@ -34,8 +36,8 @@ const MessageBody = ({ message, messageLabel, fontSize }) => (
 );
 
 export default function SearchMessage({ message }: Pick<TMessageProps, 'message'>) {
+  const fontSize = useAtomValue(fontSizeAtom);
   const UsernameDisplay = useRecoilValue<boolean>(store.UsernameDisplay);
-  const fontSize = useRecoilValue(store.fontSize);
   const { user } = useAuthContext();
   const localize = useLocalize();
 

client/src/components/Chat/Messages/ui/MessageRender.tsx

@@ -1,4 +1,5 @@
 import React, { useCallback, useMemo, memo } from 'react';
+import { useAtomValue } from 'jotai';
 import { useRecoilValue } from 'recoil';
 import { type TMessage } from 'librechat-data-provider';
 import type { TMessageProps, TMessageIcon } from '~/common';
@@ -9,6 +10,7 @@ import HoverButtons from '~/components/Chat/Messages/HoverButtons';
 import MessageIcon from '~/components/Chat/Messages/MessageIcon';
 import { Plugin } from '~/components/Messages/Content';
 import SubRow from '~/components/Chat/Messages/SubRow';
+import { fontSizeAtom } from '~/store/fontSize';
 import { MessageContext } from '~/Providers';
 import { useMessageActions } from '~/hooks';
 import { cn, logger } from '~/utils';
@@ -58,8 +60,8 @@ const MessageRender = memo(
       isMultiMessage,
       setCurrentEditId,
     });
+    const fontSize = useAtomValue(fontSizeAtom);
     const maximizeChatSpace = useRecoilValue(store.maximizeChatSpace);
-    const fontSize = useRecoilValue(store.fontSize);
 
     const handleRegenerateMessage = useCallback(() => regenerateMessage(), [regenerateMessage]);
     const hasNoChildren = !(msg?.children?.length ?? 0);

client/src/components/Messages/ContentRender.tsx

@@ -1,5 +1,6 @@
-import { useRecoilValue } from 'recoil';
 import { useCallback, useMemo, memo } from 'react';
+import { useAtomValue } from 'jotai';
+import { useRecoilValue } from 'recoil';
 import type { TMessage, TMessageContentParts } from 'librechat-data-provider';
 import type { TMessageProps, TMessageIcon } from '~/common';
 import ContentParts from '~/components/Chat/Messages/Content/ContentParts';
@@ -9,6 +10,7 @@ import HoverButtons from '~/components/Chat/Messages/HoverButtons';
 import MessageIcon from '~/components/Chat/Messages/MessageIcon';
 import { useAttachments, useMessageActions } from '~/hooks';
 import SubRow from '~/components/Chat/Messages/SubRow';
+import { fontSizeAtom } from '~/store/fontSize';
 import { cn, logger } from '~/utils';
 import store from '~/store';
 
@@ -60,8 +62,8 @@ const ContentRender = memo(
       isMultiMessage,
       setCurrentEditId,
     });
+    const fontSize = useAtomValue(fontSizeAtom);
     const maximizeChatSpace = useRecoilValue(store.maximizeChatSpace);
-    const fontSize = useRecoilValue(store.fontSize);
 
     const handleRegenerateMessage = useCallback(() => regenerateMessage(), [regenerateMessage]);
     const isLast = useMemo(

client/src/components/Nav/SettingsTabs/Chat/FontSizeSelector.tsx

@@ -1,15 +1,14 @@
-import { useRecoilState } from 'recoil';
+import { useAtom } from 'jotai';
-import { Dropdown, applyFontSize } from '@librechat/client';
+import { Dropdown } from '@librechat/client';
+import { fontSizeAtom } from '~/store/fontSize';
 import { useLocalize } from '~/hooks';
-import store from '~/store';
 
 export default function FontSizeSelector() {
-  const [fontSize, setFontSize] = useRecoilState(store.fontSize);
   const localize = useLocalize();
+  const [fontSize, setFontSize] = useAtom(fontSizeAtom);
 
   const handleChange = (val: string) => {
     setFontSize(val);
-    applyFontSize(val);
   };
 
   const options = [

client/src/components/Share/Message.tsx

@@ -1,4 +1,4 @@
-import { useRecoilValue } from 'recoil';
+import { useAtomValue } from 'jotai';
 import type { TMessageProps } from '~/common';
 import MinimalHoverButtons from '~/components/Chat/Messages/MinimalHoverButtons';
 import MessageContent from '~/components/Chat/Messages/Content/MessageContent';
@@ -6,16 +6,16 @@ import SearchContent from '~/components/Chat/Messages/Content/SearchContent';
 import SiblingSwitch from '~/components/Chat/Messages/SiblingSwitch';
 import { Plugin } from '~/components/Messages/Content';
 import SubRow from '~/components/Chat/Messages/SubRow';
+import { fontSizeAtom } from '~/store/fontSize';
 import { MessageContext } from '~/Providers';
 import { useAttachments } from '~/hooks';
 
 import MultiMessage from './MultiMessage';
 import { cn } from '~/utils';
-import store from '~/store';
 
 import Icon from './MessageIcon';
 export default function Message(props: TMessageProps) {
-  const fontSize = useRecoilValue(store.fontSize);
+  const fontSize = useAtomValue(fontSizeAtom);
   const {
     message,
     siblingIdx,

client/src/hooks/Chat/__tests__/useFocusChatEffect.spec.tsx

@@ -21,8 +21,8 @@ describe('useFocusChatEffect', () => {
     (useNavigate as jest.Mock).mockReturnValue(mockNavigate);
 
     // Mock window.matchMedia
-    window.matchMedia = jest.fn().mockImplementation(() => ({
+    window.matchMedia = jest.fn().mockImplementation((query) => ({
-      matches: false,
+      matches: query === '(hover: hover)', // Desktop has hover capability
       media: '',
       onchange: null,
       addListener: jest.fn(),
@@ -83,8 +83,8 @@ describe('useFocusChatEffect', () => {
     });
 
     test('should not focus textarea on touchscreen devices', () => {
-      window.matchMedia = jest.fn().mockImplementation(() => ({
+      window.matchMedia = jest.fn().mockImplementation((query) => ({
-        matches: true, // This indicates a touchscreen
+        matches: query === '(pointer: coarse)', // Touchscreen has coarse pointer
         media: '',
         onchange: null,
         addListener: jest.fn(),

client/src/store/fontSize.ts

@@ -0,0 +1,54 @@
+import { atom } from 'jotai';
+import { atomWithStorage } from 'jotai/utils';
+import { applyFontSize } from '@librechat/client';
+
+const DEFAULT_FONT_SIZE = 'text-base';
+
+/**
+ * Base storage atom for font size
+ */
+const fontSizeStorageAtom = atomWithStorage<string>('fontSize', DEFAULT_FONT_SIZE, undefined, {
+  getOnInit: true,
+});
+
+/**
+ * Derived atom that applies font size changes to the DOM
+ * Read: returns the current font size
+ * Write: updates storage and applies the font size to the DOM
+ */
+export const fontSizeAtom = atom(
+  (get) => get(fontSizeStorageAtom),
+  (get, set, newValue: string) => {
+    set(fontSizeStorageAtom, newValue);
+    if (typeof window !== 'undefined' && typeof document !== 'undefined') {
+      applyFontSize(newValue);
+    }
+  },
+);
+
+/**
+ * Initialize font size on app load
+ */
+export const initializeFontSize = () => {
+  if (typeof window === 'undefined' || typeof document === 'undefined') {
+    return;
+  }
+
+  const savedValue = localStorage.getItem('fontSize');
+
+  if (savedValue !== null) {
+    try {
+      const parsedValue = JSON.parse(savedValue);
+      applyFontSize(parsedValue);
+    } catch (error) {
+      console.error(
+        'Error parsing localStorage key "fontSize", resetting to default. Error:',
+        error,
+      );
+      localStorage.setItem('fontSize', JSON.stringify(DEFAULT_FONT_SIZE));
+      applyFontSize(DEFAULT_FONT_SIZE);
+    }
+  } else {
+    applyFontSize(DEFAULT_FONT_SIZE);
+  }
+};

client/src/store/settings.ts

@@ -21,7 +21,6 @@ const localStorageAtoms = {
   // General settings
   autoScroll: atomWithLocalStorage('autoScroll', false),
   hideSidePanel: atomWithLocalStorage('hideSidePanel', false),
-  fontSize: atomWithLocalStorage('fontSize', 'text-base'),
   enableUserMsgMarkdown: atomWithLocalStorage<boolean>(
     LocalStorageKeys.ENABLE_USER_MSG_MARKDOWN,
     true,