Function deliver_broadcast_turn 

async fn deliver_broadcast_turn(
    deps: &AgentTurnDeps,
    block_id: String,
    text: String,
    origin: TurnOrigin,
) -> Result<(), String>

Delivers one broadcast text to one block the way an inter-agent message reaches it (route_agent_message_from): structured controllers (persistent, ACP, App Server) take it on their own channel, which also steers a turn already running; a subprocess or not-yet-spawned persistent agent gets a turn started with origin. Either way the turn is labelled with origin where the controller tracks provenance at all (persistent and subprocess, the same agents a typed message can authorize a self-quit on).