pub fn to_parts(v: &mut Value, caches: bool)Expand description
Converts an Anthropic-layout prompt to agentplane’s shared shape (for
PromptStyle::Parts): system blocks and the first message’s content
become text parts, a cache_control breakpoint a cache mark — "1h"
for the hour, "5m" otherwise — or none when caches is off. A string
system stays as it is; a prompt without messages is left untouched.