feat: new op type for sub-agents communication (#15556)

Add `InterAgentCommunication` for v2 agent communication

codex-rs/core/src/thread_manager.rs

@@ -3,8 +3,6 @@ use crate::CodexAuth;
 use crate::ModelProviderInfo;
 use crate::OPENAI_PROVIDER_ID;
 use crate::agent::AgentControl;
-use crate::agent::inter_agent_instruction::InterAgentDelivery;
-use crate::agent::inter_agent_instruction::InterAgentInstruction;
 use crate::codex::Codex;
 use crate::codex::CodexSpawnArgs;
 use crate::codex::CodexSpawnOk;
@@ -621,18 +619,6 @@ impl ThreadManagerState {
         thread.append_message(message).await
     }
 
-    pub(crate) async fn deliver_inter_agent_instruction(
-        &self,
-        thread_id: ThreadId,
-        instruction: InterAgentInstruction,
-        delivery: InterAgentDelivery,
-    ) -> CodexResult<String> {
-        let thread = self.get_thread(thread_id).await?;
-        thread
-            .deliver_inter_agent_instruction(instruction, delivery)
-            .await
-    }
-
     /// Remove a thread from the manager by ID, returning it when present.
     pub(crate) async fn remove_thread(&self, thread_id: &ThreadId) -> Option<Arc<CodexThread>> {
         self.threads.write().await.remove(thread_id)