At the moment, callback handlers must have *args, **kwargs in their signature because run_callbacks accepts and forwards any kind of arguments, and we do not specify any guidelines.

Within koji itself, we never actually use the *args part. We always call run_callbacks with named args. Having *args is arguably useless here anyway, since there is no standard way to unpack them.

We could just drop the *args, leaving **kwargs, but then it seems a little silly to pass only **kwargs when we could just pass the dictionary directly.

Not set on what the signature should be, but thinking something like:

@callback(...)
def handler(cbtype, data): 
    ....

I'm not sure if anything else would merit top level in the signature. Perhaps some sort of opts or flags param for future growth.

Any change to callback signature would break most numerous plugins, so this would be a koji.next item.