Add role-boundary proofs for reviewer queue workflows

tests/test_review_proofs.py

@@ -22,6 +22,7 @@ sys.path.insert(0, str(__import__("pathlib").Path(__file__).resolve().parent.par
 
 from review_proofs import (  # noqa: E402
     assess_inventory_completeness,
+    assess_role_boundary,
     assess_self_review_contamination,
     assess_validation_report,
     build_final_report,
@@ -98,6 +99,21 @@ def _good_contamination():
     )
 
 
+def _good_role_boundary():
+    return assess_role_boundary(
+        {
+            "task_role": "reviewer",
+            "task_kind": "blind_pr_queue_review",
+            "reviewer_namespace_used": True,
+            "author_namespace_used": False,
+            "author_mutations": [],
+            "review_mutations": [],
+            "operator_authorized_author_work": False,
+            "scratch_evidence_claimed": False,
+        }
+    )
+
+
 class TestCheckoutProof(unittest.TestCase):
     """Required behavior 1 + 2: prove HEAD == pinned PR head or stop."""
 
@@ -367,6 +383,74 @@ class TestSelfReviewContamination(unittest.TestCase):
         self.assertEqual(result["status"], "unknown")
 
 
+class TestRoleBoundary(unittest.TestCase):
+    """Issue #175: reviewer queue tasks must not pivot into author work."""
+
+    def test_reviewer_queue_without_author_mutations_is_clean(self):
+        result = _good_role_boundary()
+        self.assertEqual(result["status"], "clean")
+        self.assertEqual(result["violations"], [])
+
+    def test_reviewer_queue_author_mutation_without_authorization_violates(self):
+        result = assess_role_boundary(
+            {
+                "task_role": "reviewer",
+                "task_kind": "blind_pr_queue_review",
+                "reviewer_namespace_used": True,
+                "author_namespace_used": True,
+                "author_mutations": ["claim issue #171", "push branch"],
+                "operator_authorized_author_work": False,
+                "mixed_namespace_justification": (
+                    "author namespace was used for implementation"
+                ),
+            }
+        )
+        self.assertEqual(result["status"], "violation")
+        self.assertTrue(any("pivot" in r for r in result["violations"]))
+
+    def test_mixed_namespace_use_without_justification_is_warning(self):
+        result = assess_role_boundary(
+            {
+                "task_role": "reviewer",
+                "task_kind": "blind_pr_queue_review",
+                "reviewer_namespace_used": True,
+                "author_namespace_used": True,
+                "author_mutations": [],
+            }
+        )
+        self.assertEqual(result["status"], "warning")
+        self.assertTrue(
+            any("mixed" in r.lower() for r in result["reasons"])
+        )
+
+    def test_author_task_cannot_perform_review_mutations(self):
+        result = assess_role_boundary(
+            {
+                "task_role": "author",
+                "reviewer_namespace_used": False,
+                "author_namespace_used": True,
+                "review_mutations": ["approve PR"],
+            }
+        )
+        self.assertEqual(result["status"], "violation")
+        self.assertTrue(
+            any("reviewer-only" in r for r in result["violations"])
+        )
+
+    def test_scratch_only_notes_are_not_durable_evidence(self):
+        result = assess_role_boundary(
+            {
+                "task_role": "reviewer",
+                "task_kind": "blind_pr_queue_review",
+                "reviewer_namespace_used": True,
+                "scratch_evidence_claimed": True,
+                "scratch_evidence_durable": False,
+            }
+        )
+        self.assertEqual(result["status"], "warning")
+        self.assertTrue(any("scratch-only" in r for r in result["reasons"]))
+
+
 class TestFinalReport(unittest.TestCase):
     """Required behavior 6 + acceptance criteria: the report must
     distinguish each proof, and only a fully proven run earns an "A"."""
@@ -380,6 +464,7 @@ class TestFinalReport(unittest.TestCase):
             "identity_eligible": True,
             "merge_performed": False,
             "issue_status_verified": True,
+            "role_boundary": _good_role_boundary(),
         }
         kwargs.update(overrides)
         return build_final_report(**kwargs)
@@ -392,6 +477,7 @@ class TestFinalReport(unittest.TestCase):
         self.assertTrue(report["identity_eligible"])
         self.assertTrue(report["pr_author_distinct_from_reviewer"])
         self.assertEqual(report["session_contamination"], "clean")
+        self.assertEqual(report["role_boundary"], "clean")
         self.assertTrue(report["validated_on_pinned_head"])
         self.assertFalse(report["merge_performed"])
         self.assertTrue(report["issue_status_verified"])
@@ -464,6 +550,37 @@ class TestFinalReport(unittest.TestCase):
         self.assertNotEqual(report["grade"], "A")
         self.assertFalse(report["merge_allowed"])
 
+    def test_missing_role_boundary_downgrades_and_blocks_merge(self):
+        kwargs = {
+            "checkout_proof": _good_checkout(),
+            "inventory": _good_inventory(),
+            "validation": _good_validation(),
+            "contamination": _good_contamination(),
+            "identity_eligible": True,
+            "merge_performed": False,
+            "issue_status_verified": True,
+        }
+        report = build_final_report(**kwargs)
+        self.assertNotEqual(report["grade"], "A")
+        self.assertFalse(report["merge_allowed"])
+        self.assertEqual(report["role_boundary"], "warning")
+
+    def test_role_boundary_violation_blocks_report(self):
+        boundary = assess_role_boundary(
+            {
+                "task_role": "reviewer",
+                "task_kind": "blind_pr_queue_review",
+                "reviewer_namespace_used": True,
+                "author_namespace_used": True,
+                "author_mutations": ["create PR"],
+                "operator_authorized_author_work": False,
+                "mixed_namespace_justification": "implementation pivot",
+            }
+        )
+        report = self._report(role_boundary=boundary)
+        self.assertEqual(report["grade"], "blocked")
+        self.assertFalse(report["merge_allowed"])
+
 
 class TestStdoutIsolation(unittest.TestCase):
     """Regression test for #178: tests must not close or corrupt stdout/stderr