Function validate_custom_arrow_schema 

pub fn validate_custom_arrow_schema(
    type_name: &str,
    schema: &Schema,
    allow_binary: bool,
) -> Result<()>

Validates that a custom Arrow write schema contains no unsupported opaque byte fields.

allow_binary is reserved for the Rust macro’s documented Vec<u8> exemption. Python schemas cannot prove that provenance and must pass false.

Errors

Returns an error naming the first opaque byte field.