Finding References in USDA

[AMZN-Gene]

I created a car.usda. Notice it contains a reference to a separate wheel.usda file.

Can I use TinyUSDZ to discover that the Wheel_01 node references wheel.usda?
I was assuming the tinyusdz::Stage's node tree would contain reference information, but I can't seem to find it.
car_with_ref.zip

[syoyo]

You should describe your question in a clear and concise manner.

[AMZN-Gene]

I can find nodes containing references without loading geometry by using tinyusdz::LoadLayerFromFile

    tinyusdz::Layer root_layer;
    bool ret = tinyusdz::LoadLayerFromFile(filepath, &root_layer, &warn, &err);
    if (warn.size()) 
    {
        std::cout << "WARN: " << warn << "\n";
    }

    if (!ret) 
    {
        std::cerr << "Failed to read USD data as Layer: \n";
        std::cerr << err << "\n";
        return -1;
    }

    std::cout << "# input\n";
    std::cout << root_layer << "\n";

    // Try to extract references (composition arc)
    // Loop over all the primary (prim) containers in the root
    // Composition arcs (like references) can only be applied on PrimSpecs
    std::vector<const tinyusdz::PrimSpec*> searchSpecs;

    for (const auto& primSpecIter : root_layer.primspecs())
    {
        const std::string name = primSpecIter.first;
        searchSpecs.push_back(&primSpecIter.second);
    }


    for (int i = 0; i < searchSpecs.size(); ++i)
    {
        const auto* primSpec = searchSpecs[i];

        // find references
        if (primSpec->metas().references.has_value())
        {
            const tinyusdz::ListEditQual referenceQual = primSpec->metas().references->first;
            const std::vector<tinyusdz::Reference> references = primSpec->metas().references->second;

            for (const auto& reference : references)
            {
                // Reference found!
                const std::string referenceAsset = reference.asset_path.GetResolvedPath(); 
            }
        }

        // add children to searchSpecs list
        for (const auto& child : primSpec->children())
        {
            searchSpecs.push_back(&child);
        }
    }

I'm still confused why this data can't be gathered from a stage (prims), and instead requires loading layers (primspecs).

[syoyo]

You also should post a minimal reproducible code interacting with Stage