Hash nested model fields by immutable value

tests/test_output_hashing.py

@@ -0,0 +1,26 @@
+from great_ai import ClassificationOutput, MultiLabelClassificationOutput, Trace
+
+
+def test_output_models_hash_nested_mutable_fields_by_value() -> None:
+    first = MultiLabelClassificationOutput(
+        labels=[
+            ClassificationOutput(
+                label="a", confidence=0.5, explanation={"tokens": ["a", "b"]}
+            )
+        ]
+    )
+    second = first.model_copy(deep=True)
+    assert hash(first) == hash(second)
+    assert len({first, second}) == 1
+
+
+def test_trace_hash_supports_its_dictionary_and_list_fields() -> None:
+    trace: Trace = Trace(
+        trace_id="id",
+        created="2026-01-01",
+        original_execution_time_ms=0,
+        logged_values={"x": [1, 2]},
+        models=[],
+        tags=["online"],
+    )
+    assert hash(trace) == hash(trace.model_copy(deep=True))