surface responses websocket close details

Author: i69699

codex-rs/codex-api/src/endpoint/responses_websocket.rs

@@ -806,10 +806,8 @@ async fn run_websocket_response_stream(
             Message::Binary(_) => {
                 return Err(ApiError::Stream("unexpected binary websocket event".into()));
             }
-            Message::Close(_) => {
-                return Err(ApiError::Stream(
-                    "websocket closed by server before response.completed".into(),
-                ));
+            Message::Close(frame) => {
+                return Err(responses_websocket_close_error(frame));
             }
             Message::Frame(_) => {}
             Message::Ping(_) | Message::Pong(_) => {}
@@ -819,6 +817,17 @@ async fn run_websocket_response_stream(
     Ok(())
 }
 
+fn responses_websocket_close_error(frame: Option<CloseFrame>) -> ApiError {
+    let message = match frame {
+        Some(frame) => format!(
+            "websocket closed by server before response.completed: code={} reason={}",
+            frame.code, frame.reason
+        ),
+        None => "websocket closed by server before response.completed".to_string(),
+    };
+    ApiError::Stream(message)
+}
+
 fn emit_responses_websocket_timing_event(
     kind: &str,
     payload: &str,
@@ -911,6 +920,36 @@ mod tests {
     use serde_json::value::to_raw_value;
     use std::collections::HashMap;
     use std::sync::Arc;
+    use tungstenite::protocol::frame::coding::CloseCode;
+
+    #[test]
+    fn websocket_close_error_preserves_code_and_reason() {
+        let error = responses_websocket_close_error(Some(CloseFrame {
+            code: CloseCode::Size,
+            reason: "Message Too Big".into(),
+        }));
+
+        let ApiError::Stream(message) = error else {
+            panic!("expected stream error");
+        };
+        assert_eq!(
+            message,
+            "websocket closed by server before response.completed: code=1009 reason=Message Too Big"
+        );
+    }
+
+    #[test]
+    fn websocket_close_error_without_frame_preserves_generic_message() {
+        let error = responses_websocket_close_error(None);
+
+        let ApiError::Stream(message) = error else {
+            panic!("expected stream error");
+        };
+        assert_eq!(
+            message,
+            "websocket closed by server before response.completed"
+        );
+    }
 
     #[test]
     fn direct_serialization_preserves_websocket_request_payload() {