A simple Jupyter Server extension that adds the server's User Token (if it exists) into the process's environment as JUPYTER_SERVER_USER_TOKEN.
Some frontend extensions and visualisation libraries use iframes to render documents served out on Jupyter Server Proxy.
These iframes might have an href target like: /proxy/index.html?some=query-params and work happily when used in notebooks and lab.
In the context of myst the same visualisations run into issues when connecting to remote Jupyter servers running on different origins, as the cookie-based auth in play in a same-origin lab front ends, will fail on a typlical myst website.
By exposing the user token, end user code can do something about this and supply the user token string to the library / extension code that needs it.
Add the package to your pip dependencies or install to your local environmnt
python -m pip install jupyter-extension-user-token
Verify a local installation
python -m jupyter server extension list