So what exactly is the input to Claude for a multi-turn conversation? I assume delimiters are being added to distinguish the user vs Claude turns (else a prefill would be the same as just ending your input with the prefill text)?

> So what exactly is the input to Claude for a multi-turn conversation?

No one (approximately) outside of Anthropic knows since the chat template is applied on the API backend; we only known the shape of the API request. You can get a rough idea of what it might be like from the chat templates published for various open models, but the actual details are opaque.