One Claude agent told other Claude agent via CLAUDE.md to do things certain way.

The way Claude did it triggered the ban - i.e. it used all caps which apparently triggers some kind of internal alert, Anthropic probably has some safeguards to prevent hacking/prompt injection and what the first Claude did to CLAUDE.md triggered this safeguard.

And it doesn't look like it was a proper use of the safeguard, they banned for no good reason.