At the moment all modules are overlaid with patches and those patches are hashed and tracked in source.json.

Many modules probably just need a MODULE.bazel file and some buildfiles. I think it would be nice UX improvement if those files could be put into the BCR directly and have some mechanism to "automatically" overlay these Bazel-specific files.

Since we already have MODULE.bazel in the BCR without patches, it might be viable to have some sort of overlay mechanism, maybe even an overlays directory that adds Starlark files directly on top of the external repository.

Such an approach would be somewhat similar to how it feels like to work in nixpkgs: Have the build overlays as regular source code and only use patches for things that are "true" functionality-changing patches.

I believe this could make it nicer to browse the BCR and get inspiration. It would also make it easier to spot functional changes and would potentially reduce the friction of having to generate patch files all the time.