I am in the very early stages of building my own layout plugin for d2 and everything works mostly well, however I am forced to use build tags in order to exclude the built-in plugins. This is due to their built tags being negative instead of positive. It would probably be better to have the built-in plugins in a separate package, but changing the build tag system from //go:build !nodagre to //go:build bundledagre and then including these in your release scripting would also work. Willing to submit a PR, if needed.