We've been working recently to create a canonical specification for the JSON-RPC api in execution clients. Progress has been relatively good so far, but we're reaching the limits of what's possible without more serious testing infrastructure.
A few things that I think could be done:
- integrate the Open RPC spec into Hive and test edge cases against clients to make sure they are all in agreement and that spec is in agreement
- some sort of intelligent fuzzing of the RPCs, while validating responses against the spec
- generally improving the readability of the spec
dm me on discord or twitter for more info