Unfortunately I already ran into my first "bummer" with Mermaid.
The diagrams render nicely in the HTML version of the @ProjectJupyter#JupyterBook, but we did not get the export to PDF (via HTML and pyppeteer) to work 😩 .
@lavergnetho For me it was a game changer in gitlab (and now GitHub) issues: the ability to easily use sequence diagrams when designing software as a team is♥️
What seems to be missing ATM is the possibility to give graph names and reuse these names in other graphs (as subgraphs). That would allow graphs to be reusable across different project, without copy-paste. But most probably not easy as it sounds.