Hi all,
I built a small JupyterLab 4 extension for research notebooks and just released 0.4.0.
What it does: when a notebook mentions a paper, for example arxiv:1706.03762, doi:10.1038/nature14539 or a full arXiv or DOI URL in a markdown cell or a code comment, DevScholar underlines it, and hovering shows the title, authors, year, abstract, citation count and links. From the hover card you can open the PDF inside JupyterLab, copy the citation, or export BibTeX for every paper in the notebook. There is also a Search & Cite dialog (Cmd/Ctrl+Shift+P) that searches OpenAlex and inserts a citation into the current cell.

Install:
pip install devscholar-jupyter
or search for devscholar in the Extension Manager.
Under the hood: it is a pure frontend extension, no server extension or config. Metadata comes from DataCite and OpenAlex, plus Semantic Scholar if you add a free API key in the settings.
Also: two-way Zotero and Mendeley sync for the papers in a notebook, and a “Show All Paper References” dialog.
Source and release notes: github.com/pallaprolus/devscholar-jupyter
It started as a port of my VS Code extension of the same name. Feedback on the reference formats people actually use in notebooks would be very welcome, as would ideas for other metadata sources that work from the browser.
Thanks!