preserve artifact request contract in native traces

src/clean_agent_preview.py

@@ -4438,7 +4438,10 @@ async def stream_preview(*, endpoint_url, model, messages, headers, turn_contrac
                 request = provider_compatible_tool_choice_request(request, model)
                 if artifact_write_phase and not successful_artifact_write:
                     yield event({
-                        'type': 'provider_request_contract',
+                        # Reuse the native runner's preserved step event family
+                        # so request-boundary diagnostics survive normalization.
+                        'type': 'agent_step',
+                        'stage': 'provider_request',
                         'round': round_number,
                         'artifact_write_phase': True,
                         'offered_tools': [

tests/test_clean_agent_preview.py

@@ -4705,7 +4705,8 @@ async def test_native_stream_reserves_remaining_budget_for_required_artifact(mon
     assert recovery["calls_used"] == module.NATIVE_ARTIFACT_RESEARCH_LIMIT
     request_contract = next(
         event for event in events
-        if event.get("type") == "provider_request_contract"
+        if event.get("type") == "agent_step"
+        and event.get("stage") == "provider_request"
         and event.get("artifact_write_phase") is True
     )
     assert "write_file" in request_contract["offered_tools"]