I added CONTRIBUTING.md. I also took a look at OpenFX. My current view is that supporting OFX in the browser would be hard, since the standard and its existing tooling are not designed around wgpu or browser execution. Tooscut would likely need its own plugin model rather than adopting OFX as is.

That said, I would be very interested in hearing your thoughts if you are open to contributing or discussing what a practical plugin system should look like in this environment. Please file a GitHub issue if you can