Packages versions

miden-assembly: 0.20.2
miden-mast-package: 0.20.2

Bug description

Procedure attributes (e.g., @note_script) are correctly parsed and stored during library compilation, but they are lost after serialization/deserialization using Library::write_to_file() and Library::read_from_bytes().

This issue was discovered while implementing miden-base#2339, which requires finding procedures with @note_script attribute in serialized libraries.

How can this be reproduced?

1. Create a MASM file with a procedure annotation:

@note_script
pub proc main
    push.1 drop
end

2. Compile to library and check attributes:

let lib = assembler.assemble_library_from_dir(&dir, namespace)?;
for export in lib.exports() {
    if let Some(proc) = export.as_procedure() {
        println!("BEFORE: {:?}", proc.attributes);
        // Output: {"note_script": "None"}
    }
}

3. Serialize and deserialize:

lib.write_to_file(&path)?;
let lib2 = Library::read_from_bytes(&std::fs::read(&path)?)?;
for export in lib2.exports() {
    if let Some(proc) = export.as_procedure() {
        println!("AFTER: {:?}", proc.attributes);
        // Output: {} (empty)
    }
}

Expected: Attributes preserved
Actual: Attributes empty

Relevant log output