Function raw_conversion_preview_for 

pub fn raw_conversion_preview_for(
    session: &SessionRecord,
    config: &Config,
    executor: &(impl CommandExecutor + Sync),
) -> Result<RawConversionPreview>

Plan a local checkout’s conversion into an isolated workspace and describe it, without changing anything.

The resume preflight and the browser’s resume card both need this answer before a person confirms, and neither owns a Controller at that point, so it takes the record and the configuration directly.