feat: merge-report lease proof fields and handoff audit (#535)

Surface lease_proof_source / recovery reason from sanctioned session
provenance on gitea_merge_pr results, and block final reports that claim
manual/seeded/injected lease proof without MCP adoption evidence.

Closes #535

final_report_validator.py

@@ -14,6 +14,7 @@ from typing import Any, Callable
 import branch_cleanup_guard
 import issue_acceptance_gate
 import issue_lock_provenance
+import merger_lease_adoption
 import reviewer_handoff_consistency
 import thread_state_ledger_validator
 from mcp_native_cleanup_proof import assess_mcp_native_cleanup_proof
@@ -1263,6 +1264,24 @@ def _rule_shared_manual_lock_pr_override(report_text: str) -> list[dict[str, str
     )
 
 
+def _rule_shared_manual_lease_proof_handoff(report_text: str) -> list[dict[str, str]]:
+    """Block merge/review handoffs that claim unsafe lease seeding (#535)."""
+    result = merger_lease_adoption.assess_manual_lease_proof_handoff(report_text)
+    if result.get("proven"):
+        return []
+    return _findings_from_reasons(
+        "shared.manual_lease_proof_handoff",
+        result.get("reasons") or [],
+        field="Merge mutations",
+        severity="block",
+        safe_next_action=(
+            "use gitea_adopt_merger_pr_lease or gitea_acquire_reviewer_pr_lease; "
+            "cite lease_proof_source / adoption_comment_id; never claim manual "
+            "seeded/injected lease proof"
+        ),
+    )
+
+
 def _rule_shared_issue_acceptance_gate(report_text: str) -> list[dict[str, str]]:
     result = issue_acceptance_gate.validate_final_report_issue_acceptance(report_text)
     if not result.get("applicable") or result.get("valid"):
@@ -1459,6 +1478,7 @@ def _rule_shared_mcp_native_cleanup_proof(report_text: str) -> list[dict[str, st
 _SHARED_ISSUE_LOCK_RULES = (
     _rule_shared_issue_lock_external_state,
     _rule_shared_manual_lock_pr_override,
+    _rule_shared_manual_lease_proof_handoff,
     _rule_shared_author_reviewer_same_run,
     _rule_shared_raw_branch_delete_bypass,
     _rule_shared_canonical_state_update,