feat(detection-core): anti-shortcut probes and fitted-component admission gate

tests/test_core_probes.py

@@ -0,0 +1,52 @@
+"""Anti-shortcut probe tests for detection-core tasks 5.1-5.2 (Req 8, 9)."""
+
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
+
+from collections.abc import Mapping
+from typing import Any
+
+from openultrasast.core.probes import (  # noqa: E402
+    FittedComponentBlocked,
+    ShortcutDetected,
+    assert_no_shortcut,
+    require_admission_evidence,
+    reversed_pair_probe,
+)
+
+FIX: dict[str, Any] = {"id": "fix", "files": [{"path": "a.py", "head_lines": [[1, 10]]}], "seconds": 1.0}
+REVERSED: dict[str, Any] = {"id": "reversed", "files": [{"path": "a.py", "head_lines": [[1, 50]]}], "seconds": 1.0}
+
+
+def test_reversed_pair_probe_detects_shape_shortcut() -> None:
+    # deletion-count style component: score = lines removed -> separates fix from reversed
+    def shape_score(change: Mapping[str, Any]) -> float:
+        return float(50.0 - change["files"][0]["head_lines"][0][1])
+
+    result = reversed_pair_probe(shape_score, FIX, REVERSED)
+    assert result.separated is True
+    try:
+        assert_no_shortcut(shape_score, FIX, REVERSED)
+        raise AssertionError("shape shortcut must be detected")
+    except ShortcutDetected:
+        pass
+
+
+def test_reversed_pair_probe_passes_relation_based_component() -> None:
+    def relation_score(change: Mapping[str, Any]) -> float:
+        return float(bool(change.get("has_guard")))
+
+    assert reversed_pair_probe(relation_score, {**FIX, "has_guard": True}, {**REVERSED, "has_guard": True}).separated is False
+    assert_no_shortcut(relation_score, {**FIX, "has_guard": True}, {**REVERSED, "has_guard": True})
+
+
+def test_fitted_component_requires_holdout_and_admission_go() -> None:
+    require_admission_evidence(holdout_passed=True, admission_decision="GO")
+    for holdout, decision in ((False, "GO"), (True, "NO-GO"), (False, "NO-GO")):
+        try:
+            require_admission_evidence(holdout_passed=holdout, admission_decision=decision)
+            raise AssertionError(f"holdout={holdout} decision={decision} must block the claim")
+        except FittedComponentBlocked:
+            pass