fix: one shot end of turn (#16308)

Fix the death of the end of turn watcher

codex-rs/core/src/codex.rs

@@ -14,6 +14,7 @@ use crate::agent::AgentStatus;
 use crate::agent::Mailbox;
 use crate::agent::MailboxReceiver;
 use crate::agent::agent_status_from_event;
+use crate::agent::status::is_final;
 use crate::apps::render_apps_section;
 use crate::auth_env_telemetry::collect_auth_env_telemetry;
 use crate::commit_attribution::commit_message_trailer_instruction;
@@ -39,6 +40,7 @@ use crate::realtime_conversation::handle_start as handle_realtime_conversation_s
 use crate::realtime_conversation::handle_text as handle_realtime_conversation_text;
 use crate::render_skills_section;
 use crate::rollout::session_index;
+use crate::session_prefix::format_subagent_notification_message;
 use crate::skills_load_input_from_config;
 use crate::stream_events_utils::HandleOutputCtx;
 use crate::stream_events_utils::handle_non_tool_response_item;
@@ -2638,6 +2640,8 @@ impl Session {
             msg,
         };
         self.send_event_raw(event).await;
+        self.maybe_notify_parent_of_terminal_turn(turn_context, &legacy_source)
+            .await;
         self.maybe_mirror_event_text_to_realtime(&legacy_source)
             .await;
         self.maybe_clear_realtime_handoff_for_event(&legacy_source)
@@ -2653,6 +2657,73 @@ impl Session {
         }
     }
 
+    /// Forwards terminal turn events from spawned MultiAgentV2 children to their direct parent.
+    async fn maybe_notify_parent_of_terminal_turn(
+        &self,
+        turn_context: &TurnContext,
+        msg: &EventMsg,
+    ) {
+        if !self.enabled(Feature::MultiAgentV2) {
+            return;
+        }
+
+        if !matches!(msg, EventMsg::TurnComplete(_) | EventMsg::TurnAborted(_)) {
+            return;
+        }
+
+        let SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
+            parent_thread_id,
+            agent_path: Some(child_agent_path),
+            ..
+        }) = &turn_context.session_source
+        else {
+            return;
+        };
+
+        let Some(status) = agent_status_from_event(msg) else {
+            return;
+        };
+        if !is_final(&status) {
+            return;
+        }
+
+        self.forward_child_completion_to_parent(*parent_thread_id, child_agent_path, status)
+            .await;
+    }
+
+    /// Sends the standard completion envelope from a spawned MultiAgentV2 child to its parent.
+    async fn forward_child_completion_to_parent(
+        &self,
+        parent_thread_id: ThreadId,
+        child_agent_path: &codex_protocol::AgentPath,
+        status: AgentStatus,
+    ) {
+        let Some(parent_agent_path) = child_agent_path
+            .as_str()
+            .rsplit_once('/')
+            .and_then(|(parent, _)| codex_protocol::AgentPath::try_from(parent).ok())
+        else {
+            return;
+        };
+
+        let message = format_subagent_notification_message(child_agent_path.as_str(), &status);
+        let communication = InterAgentCommunication::new(
+            child_agent_path.clone(),
+            parent_agent_path,
+            Vec::new(),
+            message,
+            /*trigger_turn*/ false,
+        );
+        if let Err(err) = self
+            .services
+            .agent_control
+            .send_inter_agent_communication(parent_thread_id, communication)
+            .await
+        {
+            debug!("failed to notify parent thread {parent_thread_id}: {err}");
+        }
+    }
+
     async fn maybe_mirror_event_text_to_realtime(&self, msg: &EventMsg) {
         let Some(text) = realtime_text_for_event(msg) else {
             return;