NOTE: Cli-3 has changed since I made this. I've tried updating what I've seen here, but the link above is up to date as of February 2019.
Barebones example of Vue CLI 3 for Adobe CEP extensions with single file components
Huge thanks to Eric Robinson for all his help and replies here
# from ../appData/extensions
git clone https://github.com/Inventsable/vue-CLI-3-for-CEP.git
# Or if downloaded:
cd <path-to-template>
# launch a localhost:9000
# This must be done before CEP loads (with the app closed)
npm run dev
Open Adobe app and find panel in Window > Extensions > CLI 3
Changes to the source code are reactive without the need to refresh.
vue DevTools and pesticide or any other plugins correctly target panel in localhost:9000
.