Resources: Sphinx and Docutils - QuantEcon/sphinxcontrib-jupyter GitHub Wiki
The main resource for writing sphinx extensions:
https://www.sphinx-doc.org/en/master/extdev/index.html#dev-extensions
The API's are also documented:
https://www.sphinx-doc.org/en/master/extdev/index.html#apis-used-for-writing-extensions
Sphinx is based on the Docutils Project:
Specific Links to Components
Environment: https://www.sphinx-doc.org/en/master/_modules/sphinx/environment.html
Is responsible for links and asset tracking and could be used for improvments in static asset management.
Transforms: http://docutils.sourceforge.net/docs/ref/transforms.html
Themes as an installable package: https://www.sphinx-doc.org/en/master/theming.html#distribute-your-theme
Other Projects
ipynb as source files to Sphinx
The nbsphinx project looks like it allows for ipynb as sources to the sphinx compilation system. It may be a useful resource when figuring out best default behaviours from rst to ipynb conversions.