Expand description
Applying one Action to the session.
The document-scoped arms live in commands::apply_scripted, shared with
the script engine so a scripted session and a live one cannot drift. What
this adds is the arms that also move the editor: the clipboard, the
history walk, navigation, the lens, the camera, and the palette.
Action is exactly what the core executes. A file dialog, a picker
window, a document door belong to the shell, which performs them itself and
never asks the core about one — so no action is handed back here. What an
action produces — the bytes of an export, the text of a copy — is left in
the session’s Handoff list for the host to take.