Lightkone Reading and highlighting
The reader
Open a paper and press Read. The PDF opens full screen, on a phone too. Pinch or use Zoom in / Zoom out, and the moon button turns the pages dark for reading at night. Esc or the close button returns to the list, where Lightkone remembers the paper in Recently read.
No PDF yet? Get free PDF looks for an open copy (arXiv, or Unpaywall with a contact email set under Settings → PDFs). Attach PDF adds a file of your own, and Replace PDF swaps it.
Highlights and notes
Select text on a page, then tap:
- Highlight to mark it;
- Highlight + note to mark it and write a note;
- Explain (with a Claude key) to have Claude explain the passage, or an equation, in the context of the whole paper. It sees the PDF and a picture of what you selected, takes follow-up questions, and can keep its answer as the highlight's note.
Tap a highlight to edit its note or delete it. Highlights are saved in
lightkone/annotations/<paper id>.json next to the library, as plain JSON,
and never inside the PDF, so the file stays as published.
The paper's own Notes box (in its details) is for notes on the whole paper. It is searched along with everything else.
Summaries and questions
With a Claude key, a paper's details offer Summarize and Ask Claude…. When the PDF is stored, Claude reads the whole paper, not only the abstract. To ask across your whole library, use Ask at the top (see Finding papers).
Export to Obsidian
Export to Obsidian (side bar, Write) writes one Markdown note per paper,
named @<citation key>.md, with the paper's details, your highlights (each
linking back to its page in Lightkone) and your notes. Choose your vault's
folder to write the notes straight into it (Chrome and Edge), or download a
.zip. Run it again later and only the part above the marker line is
rewritten: what you wrote below it in Obsidian is kept.
Reading offline
Lightkone keeps the last 25 PDFs you opened on the device. To choose more, for a flight or a trip, open Offline papers (in the side bar under Organize, or Ctrl/⌘K):
- Pick a folder, tag, Starred or a search first. The panel then offers to keep every paper in that view, and downloads their PDFs, highlights and notes.
- On a single paper, press Keep offline in its details.
- Kept papers show an Offline label in the list. They stay until you remove them, one by one or with Remove all.
- They take space on the device, within a limit you set (500 MB to 10 GB, 2 GB at first). Keeping stops at the limit and says so.
For the app itself to open with no network, install it (Install app or Add to Home Screen) and open it once before you go.
With no network you can read, highlight and take notes. Highlights are kept on the device and saved to your storage when you are back online, even if the app was closed meanwhile. Other changes (notes, stars, folders) are saved when you are back online as long as Lightkone stays open; the top bar says Offline, saves later until then.
This applies to a bucket or a GitHub repository. With This browser only, everything is on the device already.
Reading at night
With the Dullaby plugin set up (Settings → Dullaby night reading), Read at night opens a paper in Dullaby's calm, dim reading mode.