Hello @Sajoku, @jvanbaarsen, you are correct, most of the commands in VTR have both a normal (expects and existing, attached tmux pane), and a bang (!) version that will create a pane as needed. There is also a bit of confusion as there is a function, VtrSendCommand and commands VtrSendCommandToRunner. I need to update these to simplify, but for now, this should help:
For spec running, you can use the following (with vim-rspec):
Bundle 'thoughtbot/vim-rspec'
let g:rspec_command = "VtrSendCommandToRunner! rspec {spec}"
map <Leader>t :call RunNearestSpec()<CR>