name: typo3-ckeditor5
description: "Agent Skill: CKEditor 5 development for TYPO3 v12+. Use when developing custom plugins, configuring RTE presets, or migrating from CKEditor 4. By Netresearch."

TYPO3 CKEditor 5 Skill

CKEditor 5 integration patterns for TYPO3: custom plugins, configuration, and migration.

Expertise Areas

• Architecture: Plugin system, schema/conversion, commands, UI components
• TYPO3 Integration: YAML configuration, plugin registration, content elements
• Migration: CKEditor 4→5, plugin conversion, data migration

Reference Files

• references/ckeditor5-architecture.md - Core concepts
• references/typo3-integration.md - TYPO3-specific patterns
• references/plugin-development.md - Custom plugin guide
• references/migration-guide.md - CKEditor 4→5 migration

Quick Reference

Plugin Registration (ext_localconf.php)

$GLOBALS['TYPO3_CONF_VARS']['RTE']['Presets']['my_preset'] = 'EXT:my_ext/Configuration/RTE/MyPreset.yaml';
$GLOBALS['TYPO3_CONF_VARS']['SYS']['ckeditor5']['plugins']['my-plugin'] = [
    'entryPoint' => 'EXT:my_ext/Resources/Public/JavaScript/Ckeditor/my-plugin.js',
];

Plugin Structure

packages/my-plugin/src/
├── myplugin.js           # Main plugin (requires Editing + UI)
├── mypluginediting.js    # Schema, converters, commands
├── mypluginui.js         # Toolbar buttons, dropdowns
└── myplugincommand.js    # Command implementation

Backend Integration (nr-llm)

When integrating CKEditor plugins with TYPO3 backend services (like nr-llm for AI features):

Response Property Names

CRITICAL: Frontend JavaScript must use the exact property names returned by the backend.

// Backend returns: { content: "...", model: "...", usage: {...} }

// WRONG - will be undefined
const text = result.completion;  // Backend doesn't return 'completion'

// CORRECT - matches backend response
const text = result.content;

Real-world bug from t3x-cowriter:
- Backend CompleteResponse::success() returned content property
- Frontend used result.completion (wrong property name)
- Fix: Changed to result.content

Verification Pattern

// Log response structure during development
console.log('Backend response:', JSON.stringify(result, null, 2));

// Then use correct property
const content = result.content || '';

Migration Checklist

• [ ] Audit existing CKEditor 4 plugins
• [ ] Map features to CKEditor 5 equivalents
• [ ] Convert to class-based architecture
• [ ] Update YAML config from PageTSConfig
• [ ] Test content rendering
• [ ] Verify JS property names match backend response (if using AJAX)

Verification

./scripts/verify-ckeditor5.sh /path/to/extension

Contributing: https://github.com/netresearch/typo3-ckeditor5-skill