## Problem/Motivation The markdown editor that the AI module provides (library `ai/mdx_editor`, source in `ui/mdxeditor`) traps keyboard focus. When the caret is in the editable area, Tab inserts indentation and Shift+Tab moves inside the editor. Focus cannot leave the editor with the keyboard. A keyboard-only user cannot reach the form controls after the editor, so they cannot complete the form. This fails WCAG 2.2 SC 2.1.2 No Keyboard Trap (Level A). The editor is added to any textarea with the `data-mdxeditor` attribute (`src/Hook/FormElement.php`, `addMdxEditor()`), and to field widgets with the `use_mdx_editor` third-party setting. Forms that use it include: - the AI prompt subform (`src/Form/AiPromptSubform.php`); - the AI Agents agent form (`ai_agents`, `src/Form/AiAgentForm.php`); - the Context Control Center item form (`ai_context`, Content field). An accessibility audit of Context Control Center found this (project/ai_context#3586434+s, report by @kati.vera at Mearra, 2026-09-11, finding F2). The tester reproduced it in Firefox, Safari and Brave/Chromium, with and without VoiceOver. With VoiceOver, choosing a block type moves focus directly into the trapped area. ## Steps to reproduce 1. Open a form that uses the editor, for example `/admin/config/ai/context/items/add` with ai_context installed, or an AI Agents agent form. 2. Use Tab to move to the editor, and place the caret in the editable area. 3. Press Tab, then Shift+Tab. Expected: Tab moves focus to the next control after the editor, and Shift+Tab moves to the control before it. Or the editor documents a standard keyboard method to leave it, and the method works. Actual: Focus stays in the editor. Tab and Shift+Tab change the content or the caret position. ## Proposed resolution Options: 1. Let Tab and Shift+Tab move focus out of the editor. Keep indentation on the toolbar list buttons and on a shortcut that is not Tab. 2. Keep Tab for indentation, but add a documented way to leave the editor, for example Escape followed by Tab (the same pattern as CodeMirror). Show this in the field description and in the editor's accessible description. Option 1 is simpler for users. Option 2 keeps list indentation with Tab. Inside code blocks, the code editor can keep Tab if the same Escape method also works there. Unverified: which plugin captures Tab. The editor uses `@mdxeditor/editor` 3.52.3 with `listsPlugin`, `codeBlockPlugin`, `codeMirrorPlugin` and `diffSourcePlugin` (`ui/mdxeditor/src/components/Editor.jsx`). Check whether the Markdown source mode (the diff/source toggle) also traps Tab. ## Other findings in the same editor The same report found these in the editor. Each one is a different success criterion. Split them into separate issues if you prefer. - F3, 2.4.3 Focus Order: after Escape closes the Block type popup, focus goes to the page skip link, not back to the Block type control. VoiceOver announces "Empty group". - F7, 1.4.11 Non-text Contrast: the selected Block type option uses #F0F0F3 on #FFFFFF (about 1.14:1). - F10 and F11: at 200% text-only zoom, editor and dropdown content is clipped. At 400% zoom (about 320 CSS pixels wide), toolbar controls overlap. ## Remaining tasks - [ ] Find which plugin captures Tab. - [ ] Choose option 1 or 2. - [ ] FunctionalJavascript test: focus the editor, press Tab, and assert that focus is on the next focusable element. Press Shift+Tab and assert that focus is on the previous one. - [ ] Retest with VoiceOver, and with keyboard only, in Firefox, Safari and Chromium. - [ ] Address other findings or create follow-up issues. ## Environment - AI module 1.5.0-rc2 (the tester's site and the local check); 1.5.x branch - `@mdxeditor/editor` 3.52.3 - Drupal 11.4.5, Gin 5.0.15 - macOS 26, Firefox, Safari, Brave/Chromium, VoiceOver > [!note] > Check the one that best describes your usage, or leave all unchecked if AI was not significantly used. > > * [ ] AI **Assisted Issue** \ > _Mainly written by a human; AI used for partial generation under full human supervision._ > > * [x] AI **Generated Issue** \ > _Mainly generated by AI, reviewed and approved by a human before this issue was created._