Here’s my setup which seems to be working nicely.

Suggested tweaks welcome!

see this twitter thread https://twitter.com/josevalim/status/1437786780464463875

so basically “soon”…

Little late to this post, but it’s now part of the phoenix_live_view library, so it’s easier to setup in a existing Phoenix project. the heex formatter can be configured with the mix format task with the following config in the .formatter.exs file:

plugins: [Phoenix.LiveView.HTMLFormatter],
inputs: [
  "*.{heex,ex,exs}", # <- include heex here 
  "priv/*/seeds.exs", 
  "{config,lib,test}/**/*.{heex,ex,exs}" # <- include heex here 
],