Custom SCM panel with user-friendly "save" workflow that abstracts away VCS concepts. Uses @theia/scm for gutter dirty-diff decorations and file explorer badges. - Backend (Node): jj CLI wrapper over RPC, handles status, diff, describe, save (describe + new + push), fetch, file show - SCM provider: registers into ScmService for dirty-diff and badges, uses jj: scheme ResourceResolver for base content - Panel: three-part ViewContainer with save section (message + button), changed files list, and expandable changelog - Changelog entries expand to show changed files, clicking opens read-only diff editors via DiffUris - Auto-fetches from remote on startup and every 60s - Push errors shown as dismissable warning, not blocking - Hides default Theia SCM panel and hijacks its keybinding - Uses latest(@-) revset to handle merge commits with multiple parents