Handle context length errors consistently across response transports (#60482)

## Why

HTTP 400 responses with `context_length_exceeded` need to reach context-window recovery so manual compaction can retry with less history. Streaming context-window failures should end the stream immediately.

## What changed

- Map `context_length_exceeded` through the shared terminal provider error parser for HTTP 400 responses and events without an HTTP status.
- Return SSE context-window failures immediately.
- Preserve retryable handling for WebSocket errors carrying HTTP 503, even when their code is `context_length_exceeded`.

## Testing

Add coverage for WebSocket status handling and immediate SSE termination with retry headers. Update the manual compaction test to verify recovery from an HTTP 400 context-window error by dropping one history item and retrying.

GitOrigin-RevId: 56d8c831c2fad2ca1318318a3b4258fcc516d689

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

@@ -1326,6 +1326,32 @@ mod tests {
         assert!(body.contains("Model does not support image inputs"));
     }
 
+    #[test]
+    fn wrapped_context_length_error_respects_http_status() {
+        for status in [400, 503] {
+            let payload = json!({
+                "type": "error",
+                "status": status,
+                "error": {"code": "context_length_exceeded"}
+            })
+            .to_string();
+            let event = parse_wrapped_websocket_error_event(&payload).unwrap();
+            let error = map_wrapped_websocket_error_event(event, payload).unwrap();
+            let error = crate::api_bridge::map_api_error(error);
+            assert_eq!(
+                matches!(
+                    error.details(),
+                    codex_protocol::error::CodexErrorDetails::ContextWindowExceeded
+                ),
+                status == 400
+            );
+            assert_eq!(
+                error.retry_delay(/*retry_count*/ 1).is_some(),
+                status == 503
+            );
+        }
+    }
+
     #[test]
     fn parse_wrapped_websocket_error_event_with_connection_limit_maps_retryable() {
         let payload = json!({