It's quite worrying that I have several times in the last few months had to really drive home why people should probably not be building bespoke agentic systems just to essentially act as a half baked version of an agentic coding tool when they could just go use Claude code and instead focus their efforts on creating value rather than instant technical debt.

You can pretty much completely reprogram agents just by passing them through a smart proxy. You don't need to rewrite claude/codex, just add context engineering and tool behaviors at the proxy layer.