Scope of future plan

Hi,

Is it possible to have a plan being valid in a specific scope of a R session only, i.e. to have multiple plans in the same R session?

I know it is possible to specify the workers for the plan, but is it possible to have multiple plans? future({}) does not seem to have an option for specifying a plan either.

cl <- parallel::makePSOCKcluster(1L,rscript_libs='E:/rpackages')
parallel::clusterEvalQ(cl, { .libPaths('E:/rpackages') })
plan(cluster, workers = cl)

The reason I'm asking is because I would like to have separate plans/clusters for different shiny sessions that run in the same R process. The workers of the clusters need to do some setup and I'd like that to be specific to the user session only.

The idea I would have had was to rerun the plan() command before each future call, but that could mess up the promises later in the event loop?

##

**Edit:** Attached to the same question ("linking a cluster to a session") I wanted to ask whether it is possible to keep the state of a cluster after a future. I tried to assign objects to the global environment but in the following future run they all seem gone. This makes sense in the paradigm of futures being indifferent to who calls them, but as said my goal is to link a specific cluster to a session (and e.g. keep some base data in the cluster which I don't want to re-query each time).
I potentially could re-implement it with https://cran.r-project.org/web/packages/future/vignettes/future-6-future-api-backend-specification.html but I was hoping there is some trick/setting that I'm just not aware of.

It looks like constantly using the persistent=TRUE flag works in f <- future({...},persistent=TRUE). Found it by looking at the source code. Please let me know if this is not the right way to do it / think about it.

Best regards