What probably needs to exist is something like `llsed`.

The invocation would be like this

    llsed --host 0.0.0.0 --port 8080 --map_file claude_to_openai.json --server https://openrouter.ai/api

    { tag: ... from: ..., to: ..., params: ..., pre: ..., post: ...}

This sounds like the proper separation of concerns here... probably

The pre/post should probably be json-rpc that get lazy loaded.

Writing that now. Let's do this: https://github.com/day50-dev/llsed