feat: require proof-backed claims in reviewer handoff reports (Closes #395)

review_proofs.py

@@ -1725,6 +1725,11 @@ def build_final_report(checkout_proof, inventory, validation, contamination,
         if report_text
         else {"proven": True, "block": False, "reasons": []}
     )
+    proof_backed_handoff = (
+        assess_proof_backed_handoff_report(report_text)
+        if report_text and _PROOF_BACKED_HANDOFF_HINT.search(report_text)
+        else {"proven": True, "block": False, "reasons": []}
+    )
     if baseline_validation is None and report_text:
         baseline_validation = assess_reviewer_baseline_validation_proof(
             report_text=report_text,
@@ -1911,6 +1916,11 @@ def build_final_report(checkout_proof, inventory, validation, contamination,
             "reviewer baseline validation proof missing or failed (#325)"
         )
         downgrade_reasons.extend(baseline_validation.get("reasons", []))
+    if not proof_backed_handoff.get("proven"):
+        downgrade_reasons.append(
+            "proof-sensitive handoff claims lack command/tool evidence (#395)"
+        )
+        downgrade_reasons.extend(proof_backed_handoff.get("reasons", []))
 
     merge_allowed = (
         identity_eligible
@@ -4912,6 +4922,12 @@ _PR_QUEUE_CLEANUP_REPORT_HINT = re.compile(
     re.I,
 )
 
+_PROOF_BACKED_HANDOFF_HINT = re.compile(
+    r"task:\s*review-merge-pr|task mode:\s*review-merge-pr|"
+    r"review-merge-pr|controller handoff",
+    re.I,
+)
+
 
 def assess_pr_queue_cleanup_report(report_text: str | None) -> dict:
     """#390: validate PR-only cleanup final reports (one PR per run)."""
@@ -5374,3 +5390,10 @@ def assess_worktree_ownership_report(report_text, **kwargs):
     from reviewer_worktree_ownership import assess_worktree_ownership_report as _assess
 
     return _assess(report_text, **kwargs)
+
+
+def assess_proof_backed_handoff_report(report_text, **kwargs):
+    """#395: proof-sensitive review handoff claims require explicit evidence."""
+    from reviewer_proof_backed_handoff import assess_proof_backed_handoff_report as _assess
+
+    return _assess(report_text, **kwargs)