Function render_compaction_input 

pub fn render_compaction_input(
    api_messages: &[SharedMessage],
    custom_instructions: Option<&str>,
    policy: &DisclosurePolicy,
) -> RenderedCompactionInput

Render the summarization request under a disclosure policy. Pure — no network, no provider dependence. Sentinel-tested per class: excluded classes must not appear in prompt_text.