feat: drop agent ID from v2 (#17005)

codex-rs/core/src/tools/handlers/multi_agents_tests.rs

@@ -1554,7 +1554,7 @@ async fn multi_agent_v2_interrupted_turn_does_not_notify_parent() {
 }
 
 #[tokio::test]
-async fn multi_agent_v2_spawn_includes_agent_id_key_when_named() {
+async fn multi_agent_v2_spawn_omits_agent_id_when_named() {
     let (mut session, mut turn) = make_session_and_context().await;
     let manager = thread_manager();
     let root = manager
@@ -1586,7 +1586,7 @@ async fn multi_agent_v2_spawn_includes_agent_id_key_when_named() {
     let result: serde_json::Value =
         serde_json::from_str(&content).expect("spawn_agent result should be json");
 
-    assert_eq!(result["agent_id"], serde_json::Value::Null);
+    assert!(result.get("agent_id").is_none());
     assert_eq!(result["task_name"], "/root/test_process");
     assert!(result.get("nickname").is_some());
     assert_eq!(success, Some(true));

codex-rs/core/src/tools/handlers/multi_agents_v2/spawn.rs

@@ -209,7 +209,6 @@ impl ToolHandler for Handler {
         })?;
 
         Ok(SpawnAgentResult {
-            agent_id: None,
             task_name,
             nickname,
         })
@@ -269,7 +268,6 @@ impl SpawnAgentArgs {
 
 #[derive(Debug, Serialize)]
 pub(crate) struct SpawnAgentResult {
-    agent_id: Option<String>,
     task_name: String,
     nickname: Option<String>,
 }