From fc1bc011ada6b3f16da58566dc8c1a4d730cf905 Mon Sep 17 00:00:00 2001
From: Brad Hilton <brad.hilton.nw@gmail.com>
Date: Sat, 26 Sep 2026 04:51:24 +0000
Subject: [PATCH] Avoid per-node numeric type tuples in compact decoding

---
 src/art/trajectories/_compact.py              |   2 +-
 .../test_compact_decode_values.py             | 108 ++++++++++++++++++
 2 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit/trajectories/test_compact_decode_values.py

diff --git a/src/art/trajectories/_compact.py b/src/art/trajectories/_compact.py
index f6524677b..6c2965082 100644
--- a/src/art/trajectories/_compact.py
+++ b/src/art/trajectories/_compact.py
@@ -717,7 +717,7 @@ def _decode(
 
 
 def _decode_value(value: object, strings: dict[str, str]) -> pydantic.JsonValue:
-    if value is None or isinstance(value, (bool, int, float)):
+    if value is None or isinstance(value, int) or isinstance(value, float):
         return value
     if isinstance(value, str):
         return strings.get(value, value)
diff --git a/tests/unit/trajectories/test_compact_decode_values.py b/tests/unit/trajectories/test_compact_decode_values.py
new file mode 100644
index 000000000..e531da06f
--- /dev/null
+++ b/tests/unit/trajectories/test_compact_decode_values.py
@@ -0,0 +1,108 @@
+from __future__ import annotations
+
+import copy
+import random
+
+import pytest
+
+from art.trajectories import Trajectory, compact_dump, compact_validate
+from art.trajectories._compact import _decode_value
+
+
+class Integer(int):
+    pass
+
+
+class Floating(float):
+    pass
+
+
+class String(str):
+    pass
+
+
+@pytest.mark.parametrize(
+    "value",
+    [
+        None,
+        False,
+        True,
+        0,
+        -1,
+        2**200,
+        0.0,
+        -0.0,
+        float("inf"),
+        float("-inf"),
+        float("nan"),
+        Integer(3),
+        Floating(4.5),
+        String("literal"),
+        "$0",
+        "ordinary",
+    ],
+)
+def test_compact_scalar_decode_preserves_identity(value: object) -> None:
+    assert _decode_value(value, {}) is value
+
+
+def test_compact_nested_numeric_decode_preserves_values_and_container_ownership() -> (
+    None
+):
+    rng = random.Random(148)
+    scalars = [None, False, True, 0, -1, 2**200, 0.0, -0.0, 1.25, "$0", "text"]
+
+    def tree(depth: int) -> object:
+        if not depth or rng.random() < 0.45:
+            return rng.choice(scalars)
+        if rng.random() < 0.5:
+            return [tree(depth - 1) for _ in range(rng.randrange(6))]
+        return {f"key{i}": tree(depth - 1) for i in range(rng.randrange(6))}
+
+    for _ in range(150):
+        value = tree(5)
+        original = copy.deepcopy(value)
+        decoded = _decode_value(value, {})
+        assert decoded == original
+        assert value == original
+        if isinstance(value, (list, dict)):
+            assert decoded is not value
+
+    shared = {"numbers": [False, True, None, 1, 2.5]}
+    value = [shared, shared]
+    first = _decode_value(value, {})
+    second = _decode_value(value, {})
+    assert isinstance(first, list) and isinstance(second, list)
+    assert first[0] is not first[1] and first[0] is not second[0]
+    first_item = first[0]
+    assert isinstance(first_item, dict)
+    numbers = first_item["numbers"]
+    assert isinstance(numbers, list)
+    numbers.append(7)
+    assert second == value
+    assert first[1] == shared
+
+
+@pytest.mark.parametrize("value", [b"invalid", (1, 2), {1}, 1j, {1: "bad key"}])
+def test_compact_decode_still_rejects_non_json_values(value: object) -> None:
+    with pytest.raises(ValueError):
+        _decode_value(value, {})
+
+
+def test_compact_validation_keeps_repeated_decodes_independent() -> None:
+    trajectory = Trajectory(
+        messages_and_choices=[
+            {"role": "user", "content": "public question"},
+            {"role": "assistant", "content": "public response"},
+        ],
+        metadata={"numbers": [None, False, True, 1, 2.5]},
+    )
+    payload = compact_dump(trajectory)
+    original = copy.deepcopy(payload)
+    first = compact_validate(payload, type=Trajectory)
+    second = compact_validate(payload, type=Trajectory)
+    assert first.model_dump() == second.model_dump() == trajectory.model_dump()
+    first.metadata["numbers"].append(6)
+    assert payload == original
+    assert second.model_dump() == trajectory.model_dump()
+    assert compact_dump(second) == original