Guidance on adding a plugin to install local firefox + arkenfox user.js

[lestephane]

Is your feature request related to a problem? Please describe

I'd like to have a project local Firefox profile, with a optional customized user.js from Arkenfox.

I know there's https://github.com/vincentvanbush/asdf-firefox but installing it using asdf direnv local fails:

asdf direnv local firefox latest
▶ asdf plugin-add firefox # ...  plugin firefox not found in repository
✔️
▶ asdf install firefox latest # ...  No such plugin: firefox
❗️ Failed with status 1

This is just about the extent of what I know about the problem, which I'm ready to solve if someone can point me in the right direction along the way. Where do I start?

Describe the proposed solution

1. Add a firefox plugin that can be used with asdf direnv local
2. Add a arkenfox plugin that can be used with asdf direnv local and injects the requested version of Arkenfox in the currently configured firefox profile
3. In 2. protect against existing user customization overrides

Describe similar asdf features and why they are not sufficient

• There is to my knowlege no firefox plugin that works out of the box with asdf direnv local.
• https://github.com/vincentvanbush/asdf-firefox does not verify any checksum or signature.

Describe other workarounds you've considered

I've tried adding a user.js directly in '$HOME/.mozilla/firefox/'
I don't like messing with this HOME directory, and the profile names look absolutely horrible.
I'd rather have a local .firefox directory in a project-local directory, with a user.js file that symlinks
to a project.local Arkenfox user.js.