Function apply_scripted 

pub fn apply_scripted(act: Act, drawing: &mut Drawing<'_>) -> ScriptedApply

Apply the document-scoped subset of Act — the arms that write nothing but the drawing. The app’s dispatcher routes these same arms here, so a scripted session and a live one cannot drift. The gesture the caller opened owns the sealing: every write lands in its sink, and the solve rider re-routes what these arms disturbed.