This is not what the article is talking about. Its talking about policy documents not it forgetting something 5 prompts ago. In fact you adding things to CLAUDE.md is more what its talking about.
Conceptually the same thing though. Claude.md is sourced at the beginning of the session, so will be pretty far back in context, just like user prompts from the beginning of the session.
Claude is a next-token predictor, appending to a long text document. Prompts aren't an independent kind of thing from policy documents. It's all text in the backscroll.