fix(ai): allow null OpenAI Responses error fields

apps/aether-gateway/src/ai_pipeline/finalize/tests_sync.rs

@@ -1250,6 +1250,63 @@ fn local_finalize_handles_openai_responses_openai_family_sync_response_even_when
     );
 }
 
+#[tokio::test]
+async fn local_finalize_converts_openai_responses_null_error_to_claude_cli() {
+    let payload = GatewaySyncReportRequest {
+        trace_id: "trace-openai-responses-to-claude-cli-success".to_string(),
+        report_kind: "claude_cli_sync_finalize".to_string(),
+        report_context: Some(json!({
+            "client_api_format": "claude:messages",
+            "provider_api_format": "openai:responses",
+            "model": "claude-sonnet-4-5",
+            "mapped_model": "gpt-5",
+            "needs_conversion": true,
+            "has_envelope": false,
+        })),
+        status_code: 200,
+        headers: BTreeMap::from([("content-type".to_string(), "application/json".to_string())]),
+        body_json: Some(json!({
+            "id": "resp_completed_cli_123",
+            "object": "response",
+            "model": "gpt-5",
+            "status": "completed",
+            "error": null,
+            "output": [{
+                "type": "message",
+                "id": "msg_completed_cli_123",
+                "role": "assistant",
+                "status": "completed",
+                "content": [{
+                    "type": "output_text",
+                    "text": "Done",
+                    "annotations": []
+                }]
+            }]
+        })),
+        client_body_json: None,
+        body_base64: None,
+        telemetry: None,
+    };
+
+    let outcome = maybe_build_local_core_sync_finalize_response(
+        "trace-openai-responses-to-claude-cli-success",
+        &test_decision(),
+        &payload,
+    )
+    .expect("local finalize should succeed")
+    .expect("local finalize should convert the response");
+
+    assert_eq!(outcome.response.status(), 200);
+    let response_body = to_bytes(outcome.response.into_body(), usize::MAX)
+        .await
+        .expect("response body should read");
+    let body: serde_json::Value =
+        serde_json::from_slice(&response_body).expect("response should be json");
+    assert_eq!(body["type"], "message");
+    assert_eq!(body["content"][0]["text"], "Done");
+    assert_eq!(body["stop_reason"], "end_turn");
+}
+
 #[test]
 fn local_finalize_handles_openai_chat_stream_response_from_openai_chat() {
     let body = concat!(

apps/aether-gateway/src/execution_runtime/submission.rs

@@ -483,7 +483,7 @@ pub(crate) fn has_nested_error(value: &serde_json::Value) -> bool {
         return false;
     };
 
-    if object.contains_key("error") {
+    if object.get("error").is_some_and(|error| !error.is_null()) {
         return true;
     }
     if object
@@ -500,7 +500,9 @@ pub(crate) fn has_nested_error(value: &serde_json::Value) -> bool {
         .is_some_and(|chunks| {
             chunks.iter().any(|chunk| {
                 chunk.as_object().is_some_and(|chunk_object| {
-                    chunk_object.contains_key("error")
+                    chunk_object
+                        .get("error")
+                        .is_some_and(|error| !error.is_null())
                         || chunk_object
                             .get("type")
                             .and_then(|value| value.as_str())

apps/aether-gateway/src/execution_runtime/tests.rs

@@ -11,8 +11,9 @@ use crate::ai_pipeline_api::{
     GatewayControlSyncDecisionResponse,
 };
 use crate::execution_runtime::submission::{
-    build_best_effort_local_core_error_body, resolve_core_error_background_report_kind,
-    resolve_core_success_background_report_kind, resolve_local_core_error_response_body_json,
+    build_best_effort_local_core_error_body, has_nested_error,
+    resolve_core_error_background_report_kind, resolve_core_success_background_report_kind,
+    resolve_local_core_error_response_body_json,
 };
 use crate::execution_runtime::{
     resolve_local_sync_error_background_report_kind,
@@ -251,6 +252,23 @@ fn build_best_effort_local_core_error_body_converts_claude_cli_error_to_openai_r
     );
 }
 
+#[test]
+fn has_nested_error_ignores_null_error_fields() {
+    assert!(!has_nested_error(&json!({
+        "id": "resp_completed_123",
+        "object": "response",
+        "status": "completed",
+        "error": null,
+        "output": []
+    })));
+    assert!(has_nested_error(&json!({
+        "id": "resp_failed_123",
+        "object": "response",
+        "status": "failed",
+        "error": {"message": "quota reached"}
+    })));
+}
+
 #[test]
 fn build_best_effort_local_core_error_body_converts_sync_errors_across_standard_families() {
     let cases = vec![