The right-click menu is already a command list with a header, groups, and drill-downs — it is a minibuffer that forgot how to be typed into. This makes them the same widget: right-click sets the scope, the command-line does the rest. Nothing is disabled; the menu just stops being a popup.
esc closesWhat changed in B: the popup's header line becomes the scope chip, its groups stay groups, its submenus (Add block…, Dates…, Tags…) become → drill-downs that push another chip, and the same list is what : already opens — only unscoped. One list, one renderer, one keymap, no overflow math.
more… ⇥ dropping into the same scoped minibuffer.
copy, cut, summon selection at the top of the scoped list rather than forking a surface.