♿️(frontend) fine grained accessibility for right panel

- improve semantics and aria attributes
- gives the focus to the panel when open or switching panels
- gives back the focus to the trigger element when closing the panel

src/frontend/apps/e2e/__tests__/app-impress/doc-comments.spec.ts

@@ -547,4 +547,47 @@ test.describe('Doc Comments Side Panel', () => {
       'bn-thread-mark-selected',
     );
   });
+
+  test('it checks comments accessibility', async ({ page, browserName }) => {
+    await createDoc(page, 'comment-doc-panel', browserName, 1);
+
+    // Create comment thread
+    const editor = await writeInEditor({ page, text: 'Hello World' });
+    await editor.getByText('Hello').selectText();
+    await page.getByRole('button', { name: 'Add comment' }).click();
+
+    const thread = page.locator('.bn-thread');
+    await thread.getByRole('paragraph').first().fill('This is a comment');
+    await thread.locator('[data-test="save"]').click();
+
+    // Open comment side panel and check aria attributes
+    await page
+      .getByRole('button', { name: 'Show the comments sidebar' })
+      .click();
+
+    const elCommentsSidePanel = page.getByLabel('Comments side panel');
+    await expect(elCommentsSidePanel).not.toHaveAttribute('inert');
+
+    // Check panel get the focus when opening
+    await page.keyboard.press('Tab');
+    await expect(
+      elCommentsSidePanel.getByRole('button', { name: 'Filter comments' }),
+    ).toBeFocused();
+    await page.keyboard.press('Tab');
+
+    // Check the focus goes back to the button that open the side panel
+    await expect(
+      elCommentsSidePanel.getByRole('button', {
+        name: 'Close the comments sidebar',
+      }),
+    ).toBeFocused();
+    await page.keyboard.press('Enter');
+    await expect(elCommentsSidePanel).toBeHidden();
+    await expect(
+      page.getByRole('complementary', { name: 'Side panel' }),
+    ).toHaveAttribute('inert');
+    await expect(
+      page.getByRole('button', { name: 'Show the comments sidebar' }),
+    ).toBeFocused();
+  });
 });

src/frontend/apps/impress/src/features/docs/doc-editor/components/comments/CommentSideBar.tsx

@@ -1,4 +1,8 @@
-import { Button, Tooltip } from '@gouvfr-lasuite/cunningham-react';
+import {
+  Button,
+  ButtonElement,
+  Tooltip,
+} from '@gouvfr-lasuite/cunningham-react';
 import { DropdownMenu } from '@gouvfr-lasuite/ui-kit';
 import { useEffect, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
@@ -9,6 +13,7 @@ import SortingResolvedSVG from '@/assets/icons/ui-kit/filter-notification.svg';
 import SortingOpenSVG from '@/assets/icons/ui-kit/filter_list.svg';
 import { Box, ButtonCloseModal, Text } from '@/components/';
 import { useRightPanelStore } from '@/features/right-panel/stores/useRightPanelStore';
+import { useFocusStore } from '@/stores';
 
 import { useCommentSidebarStore } from './useCommentSidebarStore';
 
@@ -43,7 +48,9 @@ export const CommentSideBar = ({ onClose }: CommentSideBarProps) => {
       >
         <Box $direction="row" $align="center" $justify="space-between">
           <Box $direction="row" $align="center" $gap="2xs">
-            <Text $weight="bold">{t('Comments')}</Text>
+            <Text as="h2" $weight="bold" $size="16px" $margin="0">
+              {t('Comments')}
+            </Text>
 
             <DropdownMenu
               options={[
@@ -88,7 +95,6 @@ export const CommentSideBar = ({ onClose }: CommentSideBarProps) => {
                     e.preventDefault();
                     setOpen((o) => !o);
                   }}
-                  tabIndex={-1}
                 />
               </Tooltip>
             </DropdownMenu>
@@ -112,6 +118,8 @@ export const CommentSideBarButton = () => {
   const { t } = useTranslation();
   const { isPanelOpen, activePanel, setActivePanel, setIsPanelOpen } =
     useRightPanelStore();
+  const buttonRef = useRef<ButtonElement>(null);
+  const { addLastFocus } = useFocusStore();
 
   const isActive = isPanelOpen && activePanel === 'comments';
   const ariaLabel = isActive
@@ -120,12 +128,14 @@ export const CommentSideBarButton = () => {
 
   return (
     <Button
+      ref={buttonRef}
       size="small"
       onClick={() => {
         if (isActive) {
           setIsPanelOpen(false);
         } else {
           setActivePanel('comments');
+          addLastFocus(buttonRef.current);
         }
       }}
       aria-label={ariaLabel}

src/frontend/apps/impress/src/features/docs/doc-editor/components/comments/styles.tsx

@@ -310,6 +310,13 @@ export const DocsCommentsStyle = createGlobalStyle<{
     min-height: 0;
     overflow: auto;
 
+    .bn-editor[contenteditable="false"]{
+      &:focus-visible {
+        outline: 2px solid var(--c--globals--colors--brand-400);
+        outline-offset: -2px;
+      }
+    }
+
     .bn-threads-sidebar {
       gap: 0;
       border-radius: 0;

src/frontend/apps/impress/src/features/docs/doc-table-content/components/TableContentSideBar.tsx

@@ -1,5 +1,5 @@
-import { Button } from '@gouvfr-lasuite/cunningham-react';
-import { useEffect, useState } from 'react';
+import { Button, ButtonElement } from '@gouvfr-lasuite/cunningham-react';
+import { useEffect, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { css } from 'styled-components';
 
@@ -10,6 +10,7 @@ import { useEditorStore } from '@/docs/doc-editor/stores/useEditorStore';
 import { useHeadingStore } from '@/docs/doc-editor/stores/useHeadingStore';
 import { useRightPanelStore } from '@/features/right-panel/stores/useRightPanelStore';
 import { MAIN_LAYOUT_ID } from '@/layouts/conf';
+import { useFocusStore } from '@/stores/useFocusStore';
 
 import { Heading } from './Heading';
 
@@ -94,7 +95,9 @@ export const TableContentSideBar = ({ onClose }: TableContentSideBarProps) => {
         `}
       >
         <Box $direction="row" $align="center" $justify="space-between">
-          <Text $weight="bold">{t('Table of Contents')}</Text>
+          <Text as="h2" $weight="bold" $size="16px" $margin="0">
+            {t('Table of Contents')}
+          </Text>
           <ButtonCloseModal
             aria-label={t('Close the table of contents sidebar')}
             onClick={onClose}
@@ -140,6 +143,8 @@ export const TableContentSideBarButton = () => {
   const { t } = useTranslation();
   const { isPanelOpen, activePanel, setActivePanel, setIsPanelOpen } =
     useRightPanelStore();
+  const buttonRef = useRef<ButtonElement>(null);
+  const { addLastFocus } = useFocusStore();
 
   const isActive = isPanelOpen && activePanel === 'tableContent';
   const ariaLabel = isActive
@@ -148,12 +153,14 @@ export const TableContentSideBarButton = () => {
 
   return (
     <Button
+      ref={buttonRef}
       size="small"
       onClick={() => {
         if (isActive) {
           setIsPanelOpen(false);
         } else {
           setActivePanel('tableContent');
+          addLastFocus(buttonRef.current);
         }
       }}
       aria-label={ariaLabel}

src/frontend/apps/impress/src/features/left-panel/components/ResizableLeftPanel.tsx

@@ -148,6 +148,7 @@ export const ResizableLeftPanel = ({
       <Panel
         ref={ref}
         className="--docs--resizable-left-panel"
+        inert={!isPanelOpen}
         collapsible={!isPanelOpen}
         collapsedSize={0}
         style={{

src/frontend/apps/impress/src/features/right-panel/components/RightPanel.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react';
+import { useEffect, useLayoutEffect, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { css } from 'styled-components';
 
@@ -7,7 +7,7 @@ import { CommentSideBar } from '@/features/docs/doc-editor/components/comments/C
 import { useDocStore, useProviderStore } from '@/features/docs/doc-management';
 import { TableContentSideBar } from '@/features/docs/doc-table-content/components/TableContentSideBar';
 import { HEADER_HEIGHT } from '@/features/header';
-import { useResponsiveStore } from '@/stores';
+import { useFocusStore, useResponsiveStore } from '@/stores';
 
 import {
   RightPanelView,
@@ -22,6 +22,7 @@ export const RightPanel = () => {
   const { provider, isReady } = useProviderStore();
   const isProviderReady =
     isReady && provider && provider?.configuration.name === doc?.id;
+  const { restoreFocus } = useFocusStore();
 
   /**
    * Keep rendering the last active panel during the close animation,
@@ -40,21 +41,41 @@ export const RightPanel = () => {
     }
   }, [activePanel]);
 
+  /**
+   * Focus the panel when it opens or when the rendered panel changes,
+   * so that keyboard users are placed in the panel content immediately.
+   */
+  const panelRef = useRef<HTMLElement>(null);
+  useLayoutEffect(() => {
+    if (isPanelOpen) {
+      panelRef.current?.focus();
+    }
+  }, [isPanelOpen, renderedPanel]);
+
   if (!doc || !isProviderReady) {
     return null;
   }
 
-  const ariaLabel = isPanelOpen
-    ? t('Right panel, currently open')
-    : t('Right panel, currently closed');
+  const panelLabel =
+    renderedPanel === 'comments'
+      ? t('Comments side panel')
+      : renderedPanel === 'tableContent'
+        ? t('Table of contents side panel')
+        : t('Side panel');
 
-  const handleClose = () => setIsPanelOpen(false);
+  const handleClose = () => {
+    setIsPanelOpen(false);
+    restoreFocus();
+  };
 
   return (
     <Box
+      as="aside"
+      ref={panelRef}
+      tabIndex={-1}
       className="--docs--right-panel"
-      aria-label={ariaLabel}
-      aria-expanded={isPanelOpen}
+      aria-label={panelLabel}
+      inert={!isPanelOpen}
       $width="300px"
       $height={`calc(100dvh - ${HEADER_HEIGHT}px)`}
       $position={isMobile ? 'absolute' : 'sticky'}
@@ -76,6 +97,10 @@ export const RightPanel = () => {
           margin-left: 0rem;
           width: 0;
         `}
+
+        &:focus {
+          outline: none;
+        }
       `}
     >
       {renderedPanel === 'tableContent' && (