expose required artifacts in turn audit

src/clean_agent_preview.py

@@ -4212,6 +4212,7 @@ async def stream_preview(*, endpoint_url, model, messages, headers, turn_contrac
     ) if native_workspace_enabled else tuple()
     yield event({'type': 'turn_contract', **turn_contract.audit(), 'schema_mode': 'compact_contract_v5',
                  'native_workspace': native_workspace_enabled,
+                 'required_artifacts': list(required_artifacts),
                  'multimodal_image_count': image_context_count,
                  'attachment_reference_count': attachment_refs,
                  'image_rehydration': conversation_diagnostics.get('image_rehydration')})

tests/test_clean_agent_preview.py

@@ -4688,6 +4688,8 @@ async def test_native_stream_reserves_remaining_budget_for_required_artifact(mon
     )]
 
     events = [json.loads(chunk[6:]) for chunk in raw if "[DONE]" not in chunk]
+    turn_contract = next(event for event in events if event.get("type") == "turn_contract")
+    assert turn_contract["required_artifacts"] == ["/tmp_workspace/results"]
     recovery = next(
         event for event in events
         if event.get("type") == "completion_recovery"