License and source checkpoint for maia3_simplified.onnx

[magicolala]

Hi,

I'm working on a chess application that uses the official Maia-3 ONNX model currently served at:

https://www.maiachess.com/maia3/maia3_simplified.onnx

Before redistributing this file to users, I'm trying to document its exact provenance and licensing.

I was able to identify the following:

• CSSLab/maia3 contains the Maia-3 inference code and model architecture.
• The repository is licensed under AGPL-3.0.
• Official Maia-3 checkpoints are available on Hugging Face under UofTCSSLab/Maia3-*.
• Those repositories contain .pt checkpoints, but I could not find an explicit license declaration for the weights.
• I could not find an ONNX export script or a reference to maia3_simplified.onnx in the CSSLab/maia3 repository.
• The ONNX file reports PyTorch as its producer and is approximately 45.7 MB.

Could you clarify two points?

1. Under which license are the Maia-3 model weights distributed?

In particular, does the AGPL-3.0 license of CSSLab/maia3 also apply to the published .pt checkpoints and to maia3_simplified.onnx?

2. What is the source checkpoint and export process for maia3_simplified.onnx?

Specifically:

• Which Maia-3 checkpoint was used to produce it?
• Is the export script/configuration publicly available?
• Are there specific conversion parameters or preprocessing steps required to reproduce the ONNX artifact?

The file I'm currently identifying has:

filename: maia3_simplified.onnx
size: 45,683,686 bytes
sha256: 405bf76c15727dad8728b352c06a8f3c1b80fb2760e8d666b32485c63d75b856

I'm not asking for legal advice - I mainly want to make sure downstream applications can accurately document the model's license, provenance, and reproducible source material.

Thanks for your work on Maia and for any clarification you can provide.