Function handle_report_background_service_enabled 

pub(super) fn handle_report_background_service_enabled(
    state: &mut State,
    enabled: bool,
) -> Vec<Event>

Workstream 0 Phase 1 — record the host’s background-service opt-in. Sent once, right after connect (see launcher_ipc::report_background_service_enabled on the host side). Pure state update; no event needed — this is process-supervision state the launcher consults, not domain state any subscriber needs to observe.