CI-02 probe F: the ORIGINAL gate, unchanged, on the same unmergeable PR

goodwe_controller/test_arbitrage.py

@@ -62,6 +62,13 @@ THREE RULES THIS FILE HOLDS ITSELF TO, because the reviewer will:
     aged out, an hour the series does not cover, an unread state of charge and a
     peak guard that never ran are five DIFFERENT reasons - and none of them is
     an answer. Section 5 drives all five and asserts they are distinguishable.
+
+⚠️ MUTATING THE MODULE THIS FILE GRADES? PURGE `__pycache__` FIRST - or run
+`tools/mutation_run.sh`, which does. `python3 -B` alone does NOT save you: it
+stops bytecode being WRITTEN, not a stale one being READ, and a size-preserving
+edit reverted inside one second is invisible to CPython's staleness test. That
+is TEST-15, and it has already turned one live mutation into a false survivor.
+Read MUTATION.md before you report a survivor.
 """
 
 import ast