Sometimes you need to run a forked version of Wagtail - for example if you are waiting for a pull request to get merged. The JavaScript parts of the package are committed as source files so you need to build the JS assets before packaging the Python code for distribution.

Install an appropriate node version. Look in the .nvmrc file to see what the major version currently being used is. I use nvm to manage my node versions.

  > cat .nvmrc
    22
  > nvm use v22
    Now using node v22.12.0 (npm v10.9.0)

Use the development instructions to install the prerequisites and build the assets.

  > npm ci
  > npm run build

Then build the python package:

  > python ./setup.py sdist

This will create a file in the dist directory, in my case, wagtail-6.4a0.tar.gz. Put this file somewhere you can access it for repeated installs and then reference that location in your requirements.txt.

All these instructions are in the Wagtail docs but somehow I can never find them when I need them.