Function make_handler 

pub fn make_handler(
    cache: EditorStateHandle,
) -> impl FnMut(EditorWriteRequest) -> Vec<Effect> + Send + 'static

Build the per-item handler for the generic inbound primitive (SubsystemBoot::inbound). Maps one request to its Effect (or none, on ok=false), resolves the oneshot, and returns the effect(s) for the host to apply. The generic bus owns the channel, the per-tick try_recv loop, and the off-keystroke wake.