I would love a mode for conda env update -f environment.yml that functions a bit more like pip install -r requirements.txt in terms of dong less unneeded work. In particular, I would like it to avoid updating packages that don't need updating, and ideally avoid talking to the index at all if the environment.yml is already satisfied.

I think update_dependencies: False does part of this, but it doesn't apply to explicitly listed dependencies. In general, there appears to be no available operation to say "Given this environment.yml, make the fewest possible changes to satisfy its specification." My particular goals:

1. conda env update with an already satisfied environment.yml should install no packages, make no network requests, and in general complete as fast as possible.
2. if spec is partially satisfied, do not update packages that already satisfy their requirement, unless it is required to satisfy the packages that will be installed

I would like this behavior for conda install as well, such that I could call conda install notebook and it would only perform any actions if notebook is not up to date.

Are there existing combinations of flags that accomplish some or all of this?