Hi,
often I use the command enter is order to do some action on a specific repository.

The issue that I'm facing is that - maybe due low brain's memory resources - I forget if I'm still inside the vcsh subshell or if I already quit it. Therefore at current time I've aliased the command to the following:

#!/bin/bash                                                                                                                                            

[ "$1" == "enter" ] && repo=$2 || repo=$1
PS1="($repo) $ " $SHELL /usr/bin/vcsh $@

Do you thing could make sense integrate such functionality into vcsh itself? It would be enough to patch appropriately where the variable $SHELL is used.
For bash could work something like like: bash --rcfile <(echo "PS1=\"(change) ${PS1}\"")