fix: bound model stream aggregation and close failed responses

tests/unit/test_request_diagnostics.py

@@ -226,7 +226,7 @@ def test_tool_deltas_are_counted_once_without_retaining_arguments():
         [2, 1],
         strict=True,
     ):
-        assert tool == {
+        expected = {
             "name": name,
             "call_id": call_id,
             "chunk_index": index,
@@ -237,6 +237,7 @@ def test_tool_deltas_are_counted_once_without_retaining_arguments():
             "argument_prefixes": [],
             "argument_encoding_valid": True,
         }
+        assert {key: tool[key] for key in expected} == expected
     assert attempt.data["response_status"] == "completed"
     assert "private" not in json.dumps(engine.records, default=str)
     assert "secret" not in json.dumps(engine.records, default=str)