I'd hope we have more specific guidelines on how samplers should implement or use this API. _Originally posted by @yebai in https://github.com/TuringLang/AbstractMCMC.jl/pull/182#discussion_r2467194991_ EDIT: It may be a good idea to deprecate `getstats` in favour of [`AbstractMCMC.ParamsWithStats`](https://github.com/TuringLang/AbstractMCMC.jl/blob/a37c274342828a67d54c1d6d1f012804b339a619/src/callbacks.jl#L172-L198).