Hi everyone,

I’d like to suggest (or ask for help building) a plugin or userscript for Zotero.

Problem:
When browsing an article page, I often use the Zotero Connector to import it. Sometimes I realize later that the same article was already in my library, which creates duplicates. Zotero has a “Find Duplicates” feature, but this only works after importing.

Idea / Request:
It would be extremely helpful if the Connector (or a companion plugin) could:

Check whether the DOI (or PMID / arXiv ID) of the article is already present in my Zotero library (via the API).

Show a small notification or badge directly on the article page (before I import), saying “Already in library” or “Not in library”.

Attempts so far:
I know about DOI Manager and Better BibTeX, but these don’t give real-time feedback on article pages.

Question:
Has anyone already built something like this? Or would anyone be interested in helping me (or the community) create a small extension/userscript that does this check automatically?

Thanks in advance — I think many users could benefit from such a tool!