Apron
Originally titled "Babricated Forge", Apron is a mod for Minecraft Beta 1.7.3 that adds compatibility with the mods of the era (and those that were made by some very short-sighted developers later on) to the Fabric modding environment.
Apron was originally intended to only offer a compatibility layer with API mods of the time. This would have allowed mods to interact with the APIs themselves, and nothing else! Not even the game itself would have been accessible.
Of course, this would not have helped with anything by itself.
So, soon enough, Cat Core joined the project and offered help in the form of Mod Remapping API integration.
Mod Remapping API is an API mod that can help mods that were designed for one set of mappings function under a different set of mappings by translating calls from one mapping set to another at runtime. Such as in our case: Fabric intermediary names!
Cat Core is now in charge of Apron, as I stepped down from the project when I decided to stop working on Minecraft mods.
If you'd like to chat about Apron (or indeed any other Minecraft compatibility layer), join the Fabric Compatibility Layers Discord!