feat(runtime): enforce governed mutation boundaries

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a06ba0-10aa-7ea0-b20a-4f3fac39efe9

rein_aharness/cli.py

@@ -305,7 +305,10 @@ def main(argv: list[str] | None = None) -> int:
     run.add_argument(
         "--no-metrics",
         action="store_true",
-        help="Skip writing .kaizen/metrics in the target repo",
+        help=(
+            "Skip compatibility .kaizen/metrics writes "
+            "(not permitted with repository_grant)"
+        ),
     )
     run.add_argument(
         "--stream-tool-events",