test: reject malformed recurrence result integers

Author: morluto

src/jacobian/contracts/combinatorics.py

@@ -895,7 +895,9 @@ def require_complete_replay_prefix(self) -> Self:
             raise ValueError("the greatest requested index must bind replay_scope_end")
         if any(item.value != self.replay_prefix[item.index] for item in self.values):
             raise ValueError("indexed values must match the recurrence replay prefix")
-        if self.scope == "PREFIX" and indices != tuple(range(len(indices))):
+        if self.scope == "PREFIX" and indices != tuple(
+            range(self.replay_scope_end + 1)
+        ):
             raise ValueError(
                 "PREFIX results must contain consecutive indices from zero"
             )

src/jacobian_checkers/recurrence_series.py

@@ -162,6 +162,7 @@ def _validate_recurrence_values(
         if (
             not isinstance(item, dict)
             or set(item) != {"index", "value"}
+            or type(item["index"]) is not int
             or item["index"] != index
             or _fraction(item["value"], max_digits=32_768) != replay[index]
         ):
@@ -281,6 +282,7 @@ def _p_recursive_residuals_match(
     return all(
         isinstance(item, dict)
         and set(item) == {"index", "value"}
+        and type(item["index"]) is int
         and item["index"] == index
         and _fraction(item["value"], max_digits=32_768) == residual
         and residual == 0
@@ -354,7 +356,12 @@ def _replay_polynomial_coefficient_recurrence(
         return False
     initial = _fractions(source["initial_values"], minimum=1, maximum=16, max_digits=64)
     order = len(polynomials) - 1
-    if len(initial) != order or result["recurrence_order"] != order:
+    if (
+        len(initial) != order
+        or type(result["recurrence_order"]) is not int
+        or not 1 <= result["recurrence_order"] <= 16
+        or result["recurrence_order"] != order
+    ):
         return False
     raw_indices = source["indices"]
     if not isinstance(raw_indices, list) or len(raw_indices) > 256:

tests/component/checkers/test_recurrence_series_checker.py

@@ -224,3 +224,28 @@ def test_recurrence_series_checker_has_no_sympy_or_producer_dependency() -> None
     source = inspect.getsource(checker_module)
     assert "import sympy" not in source
     assert "domains.combinatorics" not in source
+
+
+@pytest.mark.parametrize(
+    ("path", "value"),
+    [
+        (("recurrence_order",), True),
+        (("values", 0, "index"), False),
+        (("residuals", 0, "index"), True),
+    ],
+)
+def test_polynomial_recurrence_checker_rejects_boolean_result_integers(
+    path: tuple[str | int, ...],
+    value: bool,
+) -> None:
+    forged = copy.deepcopy(_CASES[1][1])
+    target: Any = forged["candidate"]["payload"]
+    for key in path[:-1]:
+        target = target[key]
+    target[path[-1]] = value
+    forged["candidate"]["payload_digest"] = _digest(forged["candidate"]["payload"])
+
+    checked = check_polynomial_coefficient_recurrence_evaluation(forged)
+
+    assert checked["accepted"] is False
+    assert checked["conclusion"] == "UNKNOWN"

tests/unit/contracts/test_recurrence_contracts.py

@@ -51,6 +51,19 @@ def _result() -> dict[str, object]:
             {"index": 2, "value": _q(2)},
             {"index": 3, "value": _q(3)},
         ],
+        [
+            {"index": 0, "value": _q(1)},
+            {"index": 2, "value": _q(2)},
+            {"index": 1, "value": _q(1)},
+            {"index": 3, "value": _q(3)},
+        ],
+        [
+            {"index": 0, "value": _q(1)},
+            {"index": 1, "value": _q(1)},
+            {"index": 2, "value": _q(2)},
+            {"index": 3, "value": _q(3)},
+            {"index": 4, "value": _q(5)},
+        ],
     ],
 )
 def test_polynomial_recurrence_result_rejects_malformed_prefix_projection(
@@ -76,6 +89,10 @@ def test_polynomial_recurrence_result_rejects_malformed_prefix_projection(
             {"index": 2, "value": _q(0)},
             {"index": 4, "value": _q(0)},
         ],
+        [
+            {"index": 3, "value": _q(0)},
+            {"index": 2, "value": _q(0)},
+        ],
     ],
 )
 def test_polynomial_recurrence_result_requires_exact_residual_range(