agent conversation fix

crates/domain/src/input.rs

@@ -164,6 +164,21 @@ pub trait InputMediator: Send + Sync {
     /// authority of the FIFO/busy state and correlation only.
     fn enqueue(&self, agent: AgentId, ticket: Ticket) -> PendingReply;
 
+    /// Headless/system enqueue: appends `ticket` to the same FIFO and marks the agent
+    /// busy, but does **not** deliver any text to the human terminal surface.
+    ///
+    /// This is for inter-agent structured/headless turns where the real transport is
+    /// [`crate::ports::AgentSession::send`] and the answer is its final response. The
+    /// mailbox ticket remains useful for queue/workstate accounting and cancellation,
+    /// but publishing [`crate::events::DomainEvent::DelegationReady`] here would leak
+    /// the same task into the user's CLI cell.
+    ///
+    /// Default keeps compatibility for simple mediators; production overrides it to
+    /// suppress delivery.
+    fn enqueue_silent(&self, agent: AgentId, ticket: Ticket) -> PendingReply {
+        self.enqueue(agent, ticket)
+    }
+
     /// Registers (or refreshes) the live input [`PtyHandle`] of `agent` so a later
     /// [`InputMediator::enqueue`] delivers the turn through it (cadrage C3 §5.2).
     ///