Function read_header_ranged 

pub fn read_header_ranged(
    src: &mut dyn RangeSource,
    format: FileFormat,
    stop: &dyn Fn() -> bool,
) -> Result<Header, RangeError>

Read one model header from src with ranged requests: SafeTensors’ first FIRST_SAFETENSORS_RANGE plus any remaining JSON; GGUF in growing ranges until the tensor infos end. File-reader bounds all hold; stop is checked before each request.