Function compute_diff_for_response 

pub fn compute_diff_for_response(
    params: &Value,
    before: &str,
    after: &str,
) -> Value

Pick the right diff shape for a response based on request flags.

Default (include_diff): compact counts only — constant-size payload that never floods agent context. Full before/after content is returned only when the caller explicitly opts in with include_diff_content (UI metadata path).