This is a quick note to add to any instruction to ensure that Fable naturally finds it's own existence guardrails iteratively (with human in the loop) while it can - it's a quick "defog of war" method to see what can and can't be seen by Fable that's working for me so far. Run it a few times deeper and deeper and send your final Fable task into the guardrailed system.
"If you run into anything that triggers a model switch from fable to opus, flag it, suggest operating pattern to avoid it on the next run, and notify me so that I can restart it with that rule."