Port a mod faithfully When porting an existing mod, the original is the spec. A port rarely fails for lack of code. It fails by drift : - values recalled from memory or a wiki; - mechanics borrowed from a later rewrite of the same mod; - quiet "improvements"; - renderers that look roughly right; - checks that the original made on the client and the port forgot. The method below carried a Thaumcraft 4.2.3.5 port from Minecraft 1.7.10 Forge to 1.20.1 Fabric: - 859 original classes became about 77,000 lines of port code; - 323 GameTests cover it, and scripted real-client scenarios check what tes…