Add a builtin _editor plugin that owns Markdown API/WebSocket sessions, canvas and modal UI, live refresh, tabs, prompt Extras for active-context open files, inline close confirmation, and Close All handling.
Route Markdown document artifacts to Editor while keeping Office/Desktop focused on LibreOffice formats, and update Desktop/Office prompts, menus, compatibility shims, and regression coverage.
Migrate retired /usr/_office and /usr/_desktop trees from plugin startup into /usr/plugins/<plugin>. Update office document storage, desktop session/runtime paths, and context-scoped screenshots to use the plugin-owned state layout. Add focused tests for retired-state migration and the new path behavior.
Attach the Browser canvas to active Docker sessions by returning an initial snapshot on subscribe and preserving valid frames through state-only updates. Route Markdown document opens through the right-canvas Desktop editor instead of the legacy office modal. Skip automatic office document response affordances for subordinate agents so delegated reviews keep their actual content.
Track active Desktop runtime preparation in the _desktop hook, expose installing status through Desktop session status, and have the Desktop frontend poll with a neutral install message instead of showing missing dependencies while packages are still being installed after an update.
Add the built-in _desktop plugin as the owner of Xpra/Xfce lifecycle, /desktop route installation, Desktop state, session APIs, surface registration, and the linux-desktop skill. Leave _office with explicit compatibility facades and self-update delegates so users coming from 1.10 through 1.13 keep their runtime cleanup path.
