Wake sleeping threads for queued agent mail (#34852)

## Why

An idle thread with an outstanding durable sleep must resume when agent work
arrives, even when that message would normally remain queued without triggering a
turn.

## What changed

- Treat any pending mailbox message as wake-up work while a durable sleep is
  attached to the thread.
- Keep requiring `trigger_turn` for idle threads that are not durably asleep.
- Cover waking a sleeping root thread from queue-only agent mail and persisting
  the message in thread history.

GitOrigin-RevId: e361ac1b104436d4d63aebfe5e2422691a1cc139

codex-rs/core/src/session/handlers.rs

@@ -280,7 +280,7 @@ pub async fn inter_agent_communication(
         .enqueue_mailbox_communication(communication)
         .await;
     crate::agent_communication::emit_agent_communication_receive(&sub_id);
-    if trigger_turn {
+    if trigger_turn || sess.has_outstanding_durable_sleep() {
         sess.maybe_start_turn_for_pending_work_with_sub_id(sub_id)
             .await;
     }

codex-rs/core/src/tasks/mod.rs

@@ -451,9 +451,18 @@ impl Session {
         turn.task = Some(running_task);
     }
 
+    /// Returns whether an extension has marked this thread as durably asleep.
+    pub(crate) fn has_outstanding_durable_sleep(&self) -> bool {
+        self.services
+            .thread_extension_data
+            .get::<codex_extension_items::sleep::SleepItem>()
+            .is_some()
+    }
+
     /// Starts a regular turn when the session is idle and pending work is waiting.
     ///
-    /// Pending work currently includes mailbox mail marked with `trigger_turn`.
+    /// Pending work includes mailbox mail marked with `trigger_turn`, or any mailbox mail while
+    /// an outstanding durable sleep is attached to the thread.
     ///
     /// This helper generates a fresh sub-id for the synthetic turn before delegating to the
     /// explicit-sub-id variant.
@@ -469,13 +478,16 @@ impl Session {
     /// Starts a regular turn with the provided sub-id when pending work should wake an idle
     /// session.
     ///
-    /// The turn is created only when there is mailbox mail marked with `trigger_turn`, and only
-    /// if the session is currently idle.
+    /// The turn is created only when the session is idle and mailbox mail either requests a turn
+    /// or can wake an outstanding durable sleep.
     pub(crate) async fn maybe_start_turn_for_pending_work_with_sub_id(
         self: &Arc<Self>,
         sub_id: String,
     ) {
-        if !self.input_queue.has_trigger_turn_mailbox_items().await {
+        if !self.input_queue.has_pending_mailbox_items().await
+            || (!self.input_queue.has_trigger_turn_mailbox_items().await
+                && !self.has_outstanding_durable_sleep())
+        {
             return;
         }
 

codex-rs/core/tests/suite/pending_input.rs

@@ -193,7 +193,7 @@ async fn steer_user_input(codex: &CodexThread, text: &str) {
         .expect("steer user input");
 }
 
-async fn submit_queue_only_agent_mail(codex: &CodexThread, text: &str) {
+async fn enqueue_queue_only_agent_mail(codex: &CodexThread, text: &str) {
     codex
         .submit(Op::InterAgentCommunication {
             communication: InterAgentCommunication::new(
@@ -206,6 +206,10 @@ async fn submit_queue_only_agent_mail(codex: &CodexThread, text: &str) {
         })
         .await
         .expect("submit queue-only agent mail");
+}
+
+async fn submit_queue_only_agent_mail(codex: &CodexThread, text: &str) {
+    enqueue_queue_only_agent_mail(codex, text).await;
     codex
         .submit(Op::RealtimeConversationListVoices)
         .await
@@ -294,6 +298,64 @@ async fn wait_for_sleep_item_completed(codex: &CodexThread, call_id: &str, durat
     );
 }
 
+struct SleepingRootExtension;
+
+impl codex_extension_api::ThreadLifecycleContributor<codex_core::config::Config>
+    for SleepingRootExtension
+{
+    fn on_thread_start<'a>(
+        &'a self,
+        input: codex_extension_api::ThreadStartInput<'a, codex_core::config::Config>,
+    ) -> codex_extension_api::ExtensionFuture<'a, ()> {
+        Box::pin(async move {
+            input.thread_store.insert(SleepItem {
+                id: "clock-wait-1".to_string(),
+                duration_ms: 60_000,
+            });
+        })
+    }
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn queue_only_agent_mail_wakes_sleeping_root_and_persists_message() {
+    const CHILD_MESSAGE: &str = "worker completed";
+
+    let (server, _completions) =
+        start_streaming_sse_server(vec![response_completed_chunks("resp-1")]).await;
+    let mut extensions =
+        codex_extension_api::ExtensionRegistryBuilder::<codex_core::config::Config>::new();
+    extensions.thread_lifecycle_contributor(Arc::new(SleepingRootExtension));
+    let codex = test_codex()
+        .with_model("gpt-5.4")
+        .with_extensions(Arc::new(extensions.build()))
+        .build_with_streaming_server(&server)
+        .await
+        .expect("build Codex test session")
+        .codex;
+
+    enqueue_queue_only_agent_mail(&codex, CHILD_MESSAGE).await;
+    wait_for_turn_complete(&codex).await;
+
+    assert_eq!(server.requests().await.len(), 1);
+    let history = codex
+        .load_history(/*include_archived*/ true)
+        .await
+        .expect("load persisted thread history");
+    assert!(history.items.iter().any(|item| {
+        matches!(
+            item,
+            RolloutItem::ResponseItem(codex_protocol::models::ResponseItem::AgentMessage {
+                content,
+                ..
+            }) if content.iter().any(|content| matches!(
+                content,
+                codex_protocol::models::AgentMessageInputContent::InputText { text }
+                    if text == CHILD_MESSAGE
+            ))
+        )
+    }));
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn steer_interrupts_wait_agent_and_is_sent_in_follow_up_request() {
     const WAIT_CALL_ID: &str = "wait-call";