feat: enforce queue ordering proof in reviewer reports (Closes #321)

Add assess_queue_ordering_proof so reports cannot claim next eligible PR
without stating the queue ordering policy and proof-backed skip reasoning
for earlier actionable PRs.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

tests/test_review_proofs.py

@@ -24,6 +24,7 @@ from review_proofs import (  # noqa: E402
     ISSUE_SELECTION_CONTINUATION_EXPLICIT,
     ISSUE_SELECTION_REPRESENTED_BY_OPEN_PR,
     assess_author_pr_report,
+    assess_queue_ordering_proof,
     assess_capability_evidence,
     assess_capability_proof,
     assess_contradictory_no_pr_claim,
@@ -2160,5 +2161,111 @@ class TestCreateIssueFinalReport(unittest.TestCase):
         self.assertTrue(result["downgraded"])
 
 
+class TestQueueOrderingProof(unittest.TestCase):
+    """Issue #321: reviewer queue selection must prove ordering."""
+
+    def test_next_eligible_claim_without_policy_fails(self):
+        result = assess_queue_ordering_proof(
+            report_text="Selected the next eligible PR: PR #286.",
+        )
+        self.assertFalse(result["proven"])
+        self.assertTrue(result["claims_selection"])
+
+    def test_next_eligible_claim_with_policy_passes(self):
+        result = assess_queue_ordering_proof(
+            report_text=(
+                "Queue ordering policy: oldest PR number first\n"
+                "Selected the next eligible PR: PR #286."
+            ),
+        )
+        self.assertTrue(result["proven"])
+        self.assertEqual(result["policy"], "oldest PR number first")
+
+    def test_newest_first_api_with_oldest_first_selection_passes(self):
+        result = assess_queue_ordering_proof(
+            report_text=(
+                "Queue ordering policy: oldest PR number first\n"
+                "API order was newest-first (PR #291 before PR #286).\n"
+                "Selected the next eligible PR: PR #286."
+            ),
+            queue_ordering={
+                "policy": "oldest PR number first",
+                "selected_pr_number": 286,
+                "api_pr_numbers": [291, 286],
+            },
+        )
+        self.assertTrue(result["proven"])
+
+    def test_earlier_actionable_pr_without_skip_reason_fails(self):
+        result = assess_queue_ordering_proof(
+            report_text=(
+                "Queue ordering policy: oldest PR number first\n"
+                "Selected the next eligible PR: PR #300."
+            ),
+            queue_ordering={
+                "policy": "oldest PR number first",
+                "selected_pr_number": 300,
+                "api_pr_numbers": [300, 286],
+            },
+        )
+        self.assertFalse(result["proven"])
+        self.assertTrue(result["block"])
+
+    def test_priority_override_requires_explanation(self):
+        result = assess_queue_ordering_proof(
+            report_text="Selected the next eligible PR: PR #300.",
+            queue_ordering={
+                "policy": "priority label",
+                "selected_pr_number": 300,
+                "api_pr_numbers": [286, 300],
+            },
+        )
+        self.assertFalse(result["proven"])
+
+    def test_priority_override_with_explanation_passes(self):
+        result = assess_queue_ordering_proof(
+            report_text=(
+                "Queue ordering policy: priority label\n"
+                "Priority override: security label on PR #300.\n"
+                "Selected the next eligible PR: PR #300."
+            ),
+            queue_ordering={
+                "policy": "priority label",
+                "selected_pr_number": 300,
+                "api_pr_numbers": [286, 300],
+                "priority_override": "security label on PR #300",
+            },
+        )
+        self.assertTrue(result["proven"])
+
+    def test_build_final_report_downgrades_missing_ordering_proof(self):
+        report = build_final_report(
+            checkout_proof=_good_checkout(),
+            inventory=_good_inventory(),
+            validation=_good_validation(),
+            contamination=_good_contamination(),
+            identity_eligible=True,
+            merge_performed=False,
+            issue_status_verified=True,
+            capability_evidence=_good_capability_evidence(),
+            sweep=_good_sweep(),
+            live_state=_good_live_state(),
+            role_boundary=_good_role_boundary(),
+            review_mutation=_good_review_mutation(),
+            controller_handoff=_good_handoff(),
+            capability_proof=_good_capability_proof(),
+            sweep_proof=_good_secret_sweep(),
+            worktree_proof={
+                "worktree_path": "/repo/branches/review-feat-issue-224",
+                "porcelain_status": "",
+                "pr_scope_files": ["docs/wiki/Repositories.md"],
+                "scratch_used": True,
+            },
+            report_text="Selected the next eligible PR: PR #286.",
+        )
+        self.assertNotEqual(report["grade"], "A")
+        self.assertFalse(report["queue_ordering_proven"])
+
+
 if __name__ == "__main__":
     unittest.main()