The one that lets you hack the vendor folder

sync folders from vendor

Sometimes you'll need or want to edit files that would normally be accessible in your local
vendor folder - but you cannot with wf2 because we don't 'sync' 'vendor' by default for performance reasons.

To get around this limitiation, we can add temporary 'sync' folders

with the --sync flag

wf2 up --sync vendor/magento/framework/Acl

You can also add folders with wf2.yml or wf2.env.yml

options:
  services:
    unison:
      ignore_not:
        - vendor/wearejh

Note: If you provide both (in the yml + cli flag) then ONLY the cli flag will be used