Unused Source Finder for NotebookLM EN

You upload twenty sources to a notebook, chat with it for an hour, and still cannot tell which of them the model ever actually used. Citations show up one answer at a time, so nothing adds up across the conversation — the PDF that has never been cited once looks exactly like the one cited forty times.

This extension keeps the running tally. As answers appear, it reads the citation chips, works out which source each one points at where it can, and adds it to a count kept per notebook that survives reloads. Chips it cannot pin to a source are reported separately rather than guessed. Then it shows you the view nobody else gives you: the sources that have not been cited yet, listed first.

Useful before a cleanup ("which of these 50 sources can go?"), and useful the moment you suspect a file you uploaded is being ignored.

How to use
1. Install it and open a notebook in NotebookLM.
2. Click the Coverage button at the bottom right of the page.
3. Chat as usual. The panel updates as answers cite sources, and the badge shows how many sources have not been cited yet.

What it does
• Counts how many times each source is cited, per notebook
• Puts the sources that have not been cited yet at the top of the list
• Keeps counting across sessions, so counts build up over the life of a notebook
• Seeds the count from the answers already on screen the first time you open a notebook
• Coverage is measured from the answers loaded in your browser after you install it, not from your notebook's full history
• Shows how many citations could not be matched to a source, so a number is never presented as more certain than it is
• Treats zero as "not cited yet", not "useless" — nothing in your notebook is edited, deleted or clicked
• Runs entirely on your device — no account, no server, no sign-in
• The popup lists every notebook with stored counts and deletes them in one click
• Available in English, Korean, Japanese, Chinese and Spanish

Counts are an estimate: they reflect the answers that were rendered in your browser, and citation chips that cannot be resolved to a source are reported separately instead of being guessed.

Independent extension, not affiliated with NotebookLM.