Block author mutations from reviewer MCP namespace (Issue #209)

Add role_namespace_gate to fail closed when reviewer-bound sessions attempt
author mutations (create_pr always blocked; create_issue only when profile
explicitly grants gitea.issue.create). Extend mutation audit records with
mcp_namespace, task_role, and operation fields. Add handoff parity checks in
review_proofs for author role vs reviewer namespace mismatches.

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

review_proofs.py

@@ -1139,6 +1139,41 @@ def assess_role_route_handoff(report_text, route_result=None):
     }
 
 
+def assess_mutation_namespace_handoff(
+    *,
+    declared_role: str | None = None,
+    namespaces_used: list[str] | None = None,
+    capability_profile: str | None = None,
+):
+    """Issue #209: handoff role and capability proof must match mutation namespace."""
+    reasons = []
+    role = (declared_role or "").strip().lower()
+    namespaces = list(namespaces_used or [])
+
+    reviewer_namespaces = [
+        ns for ns in namespaces if "reviewer" in (ns or "").lower()
+    ]
+    if role == "author" and reviewer_namespaces:
+        reasons.append(
+            "author handoff reported reviewer MCP namespace for mutations")
+
+    cap = (capability_profile or "").strip().lower()
+    if cap and "author" in cap and reviewer_namespaces:
+        reasons.append(
+            "capability proof profile does not match mutation namespace "
+            f"(profile={capability_profile}, namespaces={reviewer_namespaces})")
+
+    blocked = bool(reasons)
+    return {
+        "valid": not blocked,
+        "blocked": blocked,
+        "complete": not blocked,
+        "downgraded": blocked,
+        "reasons": reasons,
+        "missing_fields": [] if not blocked else ["namespace parity"],
+    }
+
+
 def assess_capability_stop_terminal_report(
     report_text,
     *,