i'll have a look today.
this isn't documented anywhere yet, but we're unlikely to take a PR on the API repo before we see the corresponding SpiceDB code - any change to the API repo immediately becomes a part of our API documentation, and proto is intended to be highly backwards-compatible, but it does so in a way where making breaking changes is problematic.
the way we usually approach this is to create a branch on the API repo, then point the authzed-go repo at the branch on the API repo, then point SpiceDB at the authzed-go branch. this way, you can write a PR in SpiceDB without merging anything upstream.
does that make sense? I can see about documenting this more fully.