[core] add optional status_code to error events (#6865)

We want to better uncover error status code for clients. Add an optional
status_code to error events (thread error, error, stream error) so app
server could uncover the status code from the client side later.

in event log:
```
< {
<   "method": "codex/event/stream_error",
<   "params": {
<     "conversationId": "019a9a32-f576-7292-9711-8e57e8063536",
<     "id": "0",
<     "msg": {
<       "message": "Reconnecting... 5/5",
<       "status_code": 401,
<       "type": "stream_error"
<     }
<   }
< }
< {
<   "method": "codex/event/error",
<   "params": {
<     "conversationId": "019a9a32-f576-7292-9711-8e57e8063536",
<     "id": "0",
<     "msg": {
<       "message": "exceeded retry limit, last status: 401 Unauthorized, request id: 9a0cb03a485067f7-SJC",
<       "status_code": 401,
<       "type": "error"
<     }
<   }
< }
```

codex-rs/core/src/codex.rs

@@ -66,6 +66,7 @@ use crate::context_manager::ContextManager;
 use crate::environment_context::EnvironmentContext;
 use crate::error::CodexErr;
 use crate::error::Result as CodexResult;
+use crate::error::http_status_code_value;
 #[cfg(test)]
 use crate::exec::StreamOutput;
 use crate::mcp::auth::compute_auth_statuses;
@@ -79,7 +80,6 @@ use crate::protocol::ApplyPatchApprovalRequestEvent;
 use crate::protocol::AskForApproval;
 use crate::protocol::BackgroundEventEvent;
 use crate::protocol::DeprecationNoticeEvent;
-use crate::protocol::ErrorEvent;
 use crate::protocol::Event;
 use crate::protocol::EventMsg;
 use crate::protocol::ExecApprovalRequestEvent;
@@ -133,6 +133,7 @@ use codex_protocol::user_input::UserInput;
 use codex_utils_readiness::Readiness;
 use codex_utils_readiness::ReadinessFlag;
 use codex_utils_tokenizer::warm_model_cache;
+use reqwest::StatusCode;
 
 /// The high-level interface to the Codex system.
 /// It operates as a queue pair where you send submissions and receive events.
@@ -1186,9 +1187,11 @@ impl Session {
         &self,
         turn_context: &TurnContext,
         message: impl Into<String>,
+        http_status_code: Option<StatusCode>,
     ) {
         let event = EventMsg::StreamError(StreamErrorEvent {
             message: message.into(),
+            http_status_code: http_status_code_value(http_status_code),
         });
         self.send_event(turn_context, event).await;
     }
@@ -1680,6 +1683,7 @@ mod handlers {
                 id: sub_id.clone(),
                 msg: EventMsg::Error(ErrorEvent {
                     message: "Failed to shutdown rollout recorder".to_string(),
+                    http_status_code: None,
                 }),
             };
             sess.send_event_raw(event).await;
@@ -1933,10 +1937,8 @@ pub(crate) async fn run_task(
             }
             Err(e) => {
                 info!("Turn error: {e:#}");
-                let event = EventMsg::Error(ErrorEvent {
-                    message: e.to_string(),
-                });
-                sess.send_event(&turn_context, event).await;
+                sess.send_event(&turn_context, EventMsg::Error(e.to_error_event(None)))
+                    .await;
                 // let the user continue the conversation
                 break;
             }
@@ -2060,6 +2062,7 @@ async fn run_turn(
                     sess.notify_stream_error(
                         &turn_context,
                         format!("Reconnecting... {retries}/{max_retries}"),
+                        e.http_status_code(),
                     )
                     .await;
 

codex-rs/core/src/compact.rs

@@ -10,7 +10,6 @@ use crate::error::Result as CodexResult;
 use crate::features::Feature;
 use crate::protocol::AgentMessageEvent;
 use crate::protocol::CompactedItem;
-use crate::protocol::ErrorEvent;
 use crate::protocol::EventMsg;
 use crate::protocol::TaskStartedEvent;
 use crate::protocol::TurnContextItem;
@@ -128,10 +127,8 @@ async fn run_compact_task_inner(
                     continue;
                 }
                 sess.set_total_tokens_full(turn_context.as_ref()).await;
-                let event = EventMsg::Error(ErrorEvent {
-                    message: e.to_string(),
-                });
-                sess.send_event(&turn_context, event).await;
+                sess.send_event(&turn_context, EventMsg::Error(e.to_error_event(None)))
+                    .await;
                 return;
             }
             Err(e) => {
@@ -141,15 +138,14 @@ async fn run_compact_task_inner(
                     sess.notify_stream_error(
                         turn_context.as_ref(),
                         format!("Reconnecting... {retries}/{max_retries}"),
+                        e.http_status_code(),
                     )
                     .await;
                     tokio::time::sleep(delay).await;
                     continue;
                 } else {
-                    let event = EventMsg::Error(ErrorEvent {
-                        message: e.to_string(),
-                    });
-                    sess.send_event(&turn_context, event).await;
+                    sess.send_event(&turn_context, EventMsg::Error(e.to_error_event(None)))
+                        .await;
                     return;
                 }
             }

codex-rs/core/src/compact_remote.rs

@@ -6,7 +6,6 @@ use crate::codex::TurnContext;
 use crate::error::Result as CodexResult;
 use crate::protocol::AgentMessageEvent;
 use crate::protocol::CompactedItem;
-use crate::protocol::ErrorEvent;
 use crate::protocol::EventMsg;
 use crate::protocol::RolloutItem;
 use crate::protocol::TaskStartedEvent;
@@ -30,10 +29,8 @@ pub(crate) async fn run_remote_compact_task(sess: Arc<Session>, turn_context: Ar
 
 async fn run_remote_compact_task_inner(sess: &Arc<Session>, turn_context: &Arc<TurnContext>) {
     if let Err(err) = run_remote_compact_task_inner_impl(sess, turn_context).await {
-        let event = EventMsg::Error(ErrorEvent {
-            message: format!("Error running remote compact task: {err}"),
-        });
-        sess.send_event(turn_context, event).await;
+        let event = err.to_error_event(Some("Error running remote compact task".to_string()));
+        sess.send_event(turn_context, EventMsg::Error(event)).await;
     }
 }
 

codex-rs/core/src/error.rs

@@ -10,6 +10,7 @@ use chrono::Local;
 use chrono::Utc;
 use codex_async_utils::CancelErr;
 use codex_protocol::ConversationId;
+use codex_protocol::protocol::ErrorEvent;
 use codex_protocol::protocol::RateLimitSnapshot;
 use reqwest::StatusCode;
 use serde_json;
@@ -430,6 +431,37 @@ impl CodexErr {
     pub fn downcast_ref<T: std::any::Any>(&self) -> Option<&T> {
         (self as &dyn std::any::Any).downcast_ref::<T>()
     }
+
+    pub fn http_status_code(&self) -> Option<StatusCode> {
+        match self {
+            CodexErr::UnexpectedStatus(err) => Some(err.status),
+            CodexErr::RetryLimit(err) => Some(err.status),
+            CodexErr::UsageLimitReached(_) | CodexErr::UsageNotIncluded => {
+                Some(StatusCode::TOO_MANY_REQUESTS)
+            }
+            CodexErr::InternalServerError => Some(StatusCode::INTERNAL_SERVER_ERROR),
+            CodexErr::ResponseStreamFailed(err) => err.source.status(),
+            CodexErr::ConnectionFailed(err) => err.source.status(),
+            _ => None,
+        }
+    }
+
+    pub fn to_error_event(&self, message_prefix: Option<String>) -> ErrorEvent {
+        let error_message = self.to_string();
+        let message: String = match message_prefix {
+            Some(prefix) => format!("{prefix}: {error_message}"),
+            None => error_message,
+        };
+
+        ErrorEvent {
+            message,
+            http_status_code: http_status_code_value(self.http_status_code()),
+        }
+    }
+}
+
+pub fn http_status_code_value(http_status_code: Option<StatusCode>) -> Option<u16> {
+    http_status_code.as_ref().map(StatusCode::as_u16)
 }
 
 pub fn get_error_message_ui(e: &CodexErr) -> String {
@@ -775,4 +807,43 @@ mod tests {
             assert_eq!(err.to_string(), expected);
         });
     }
+
+    #[test]
+    fn error_event_includes_http_status_code_when_available() {
+        let err = CodexErr::UnexpectedStatus(UnexpectedResponseError {
+            status: StatusCode::BAD_REQUEST,
+            body: "oops".to_string(),
+            request_id: Some("req-1".to_string()),
+        });
+        let event = err.to_error_event(None);
+
+        assert_eq!(
+            event.message,
+            "unexpected status 400 Bad Request: oops, request id: req-1"
+        );
+        assert_eq!(
+            event.http_status_code,
+            Some(StatusCode::BAD_REQUEST.as_u16())
+        );
+    }
+
+    #[test]
+    fn error_event_omits_http_status_code_when_unknown() {
+        let event = CodexErr::Fatal("boom".to_string()).to_error_event(None);
+
+        assert_eq!(event.message, "Fatal error: boom");
+        assert_eq!(event.http_status_code, None);
+    }
+
+    #[test]
+    fn error_event_applies_message_wrapper() {
+        let event = CodexErr::Fatal("boom".to_string())
+            .to_error_event(Some("Error running remote compact task".to_string()));
+
+        assert_eq!(
+            event.message,
+            "Error running remote compact task: Fatal error: boom"
+        );
+        assert_eq!(event.http_status_code, None);
+    }
 }