pub fn apply_cache_control(messages: &mut [Value], config: &PromptCacheConfig)Expand description
Modify the message JSON to add cache_control markers according to
config.
For Anthropic, this adds "cache_control": {"type": "ephemeral"} (or
the 1h variant) to the last content block of cached messages. For
OpenAI and None providers this is a no-op: OpenAI performs automatic
prefix caching and needs no client-side markers.