feat: guard merged branch cleanup path

Closes #514

final_report_validator.py

@@ -11,6 +11,7 @@ import inspect
 import re
 from typing import Any, Callable
 
+import branch_cleanup_guard
 import issue_lock_provenance
 from post_merge_cleanup_proof import assess_post_merge_cleanup_proof
 from review_proofs import (
@@ -1024,6 +1025,19 @@ def _rule_shared_author_reviewer_same_run(report_text: str) -> list[dict[str, st
     )
 
 
+def _rule_shared_raw_branch_delete_bypass(report_text: str) -> list[dict[str, str]]:
+    result = branch_cleanup_guard.assess_raw_branch_delete_report(report_text)
+    if not result["block"]:
+        return []
+    return _findings_from_reasons(
+        "shared.raw_branch_delete_bypass",
+        result["reasons"],
+        field="Cleanup mutations",
+        severity="block",
+        safe_next_action=result["safe_next_action"],
+    )
+
+
 def _rule_reviewer_review_mutation(
     report_text: str,
     *,
@@ -1061,6 +1075,7 @@ _SHARED_ISSUE_LOCK_RULES = (
     _rule_shared_issue_lock_external_state,
     _rule_shared_manual_lock_pr_override,
     _rule_shared_author_reviewer_same_run,
+    _rule_shared_raw_branch_delete_bypass,
 )
 
 _RULES_BY_TASK: dict[str, list[Callable[..., list[dict[str, str]]]]] = {