Function compress_clean 

pub fn compress_clean(
    env: &dyn PatternEnv,
    command: &str,
    clean_output: &str,
    output: &str,
) -> Option<String>

The policy-free part of the engine’s compress_output: everything after the protected-command gate, the leading-cd unwrap, ANSI stripping and the user filter rules, which the engine applies first. clean_output is the ANSI-stripped output, output the raw one every result is measured against.