Enum System 

pub enum System<'a> {
    Text(&'a str),
    Blocks(&'a Value),
    None,
}

System prompt input form. Anthropic accepts either a plain string or a list of content blocks; this enum mirrors that surface.

Variants

Text(&'a str)

Treated as a single {"type": "text", "text": ...} block.

Blocks(&'a Value)

Pre-built content blocks. Must be a JSON array of objects.

None

Same as passing None to the Python API.