feat: validate Selected PR: none in cleanup mode when queue is empty

pr_queue_cleanup.py

@@ -132,6 +132,13 @@ def check_cleanup_task_allowed(task: str) -> tuple[bool, list[str]]:
 _SELECTED_PR_RE = re.compile(
     r"^\s*[-*]?\s*selected pr\s*:\s*#?(\d+)", re.IGNORECASE | re.MULTILINE
 )
+_SELECTED_PR_NONE_RE = re.compile(
+    r"^\s*[-*]?\s*selected pr\s*:\s*(?:none|n/a)\b", re.IGNORECASE | re.MULTILINE
+)
+_EMPTY_QUEUE_RE = re.compile(
+    r"\b0 open pr|\bno open pr|\bno eligible pr|\bempty (?:review )?queue|\binventory empty|\btrusted_empty\b",
+    re.IGNORECASE,
+)
 _NEXT_SUGGESTED_RE = re.compile(
     r"^\s*[-*]?\s*next suggested pr\s*:", re.IGNORECASE | re.MULTILINE
 )
@@ -176,7 +183,11 @@ def assess_pr_queue_cleanup_report(report_text: str) -> dict:
 
     selected = _SELECTED_PR_RE.findall(text)
     if len(selected) == 0:
-        reasons.append("report must name exactly one Selected PR")
+        if _SELECTED_PR_NONE_RE.search(text):
+            if not _EMPTY_QUEUE_RE.search(text):
+                reasons.append("Selected PR is 'none' but no valid empty-queue claim found")
+        else:
+            reasons.append("report must name exactly one Selected PR")
     elif len(set(selected)) > 1:
         reasons.append(
             "cleanup run selected multiple PRs "
@@ -184,6 +195,9 @@ def assess_pr_queue_cleanup_report(report_text: str) -> dict:
             "PR per run"
         )
 
+    if len(selected) > 0 and _SELECTED_PR_NONE_RE.search(text):
+        reasons.append("report contains both a selected PR and a claim of none selected")
+
     terminal = _TERMINAL_MUTATION_RE.findall(text)
     if len(terminal) > 1:
         reasons.append(

tests/test_pr_queue_cleanup.py

@@ -265,5 +265,38 @@ class TestCleanupReportVerifier(unittest.TestCase):
         self.assertEqual(direct["proven"], wrapped["proven"])
 
 
+class TestCleanupEmptyQueue(unittest.TestCase):
+    def test_empty_queue_report_passes(self):
+        report = _clean_report(
+            selected="Selected PR: none",
+            decision="Review decision: comment",
+            next="Next suggested PR: approvals (queue empty)",
+            pagination="PR inventory pagination proof: inventory_complete=true, total_count 0",
+        )
+        report += "\npr_inventory_trust_gate.status: trusted_empty"
+        result = assess_pr_queue_cleanup_report(report)
+        self.assertTrue(result["proven"], result["reasons"])
+
+    def test_empty_queue_without_evidence_fails(self):
+        report = _clean_report(
+            selected="Selected PR: none",
+        )
+        result = assess_pr_queue_cleanup_report(report)
+        self.assertFalse(result["proven"])
+        self.assertTrue(
+            any("no valid empty-queue claim" in r for r in result["reasons"]),
+            result["reasons"]
+        )
+
+    def test_contradictory_selected_pr_fails(self):
+        report = _clean_report() + "\nSelected PR: none"
+        result = assess_pr_queue_cleanup_report(report)
+        self.assertFalse(result["proven"])
+        self.assertTrue(
+            any("contains both a selected PR and a claim of none selected" in r for r in result["reasons"]),
+            result["reasons"]
+        )
+
+
 if __name__ == "__main__":
     unittest.main()