# PDF reader & reading desk

Use the PDF reader for a paper opened from disk, and the reading desk for a persistent literature-reading space. Both let you select passages, inspect references and ask focused questions while keeping the original PDF intact.

## Open a research PDF

On Home choose **Open PDF**, drop a PDF, or use the desktop file association. VersoFold keeps a reading copy, extracts text with page headings and attempts to identify bibliography entries and citation locations. It leaves the original file where it was.

Use the PDF toolbar to navigate pages, zoom, fit the page and search text. External links open their destinations; internal links move within the PDF. Imported PDFs do not have editable LaTeX source merely because they are open in VersoFold.

The reference panel shows compact cards in citation order. Inspect uncertain metadata matches and choose candidates when necessary. A downloaded/attached paper can be opened from its library record.

## Open the reading desk

Choose **Reading desk** on Home or in the research reader's header. Opening it from a PDF selects that paper. The desk places the library on the left, the paper in the center and notes or the agent on the right.

**My reading** is a personal collection that works without a manuscript. The **Reading space** selector also opens workspace collections. Choose deliberately: personal notes and a paper's project notes can be different collections.

Search the library or queue by title, author, year and tags. `#tag` queries and tag filters help narrow a topic. Mark papers To read, use reading status, and star papers you want to return to. A paper can join the reading queue before its PDF has been attached.

## Compare papers and save passages

Open a second paper for a side-by-side comparison. Search within either PDF independently. A useful comparison workflow is to read both methods sections, then compare evaluation data, assumptions and limitations rather than only abstracts.

Select text and choose **Save passage**. Add a Markdown note explaining why it matters. Notes retain page links so you can return to the passage. Keep exact quotations separate from your interpretation; an extracted phrase can lose context without the surrounding page.

**Export notes** downloads Markdown for use elsewhere. Removing a missing attachment does not erase saved notes. A paper with notes cannot be removed from the collection until those notes are removed.

## Use the reading companion

Select a passage or ask a question in the desk's agent panel. The request carries the current paper's reference identity, comparison paper and selected passage when supplied. Switching papers updates that context. The assistant can retrieve attached PDFs through its reading tools.

Starter questions prepare text for you to review and send. A model connection is required for responses. For a useful request, specify the page/passage and the question: “Explain the assumption in this paragraph, then compare it with the second paper's setup.”

The assistant should read extracted text first and use page images when equations, figures or poor extraction require visual inspection. It should distinguish what the source says from its own explanation.

## Know the extraction limits

PDF text order can be imperfect for columns, tables, ligatures and equations. Scanned pages may contain no searchable text. OCR is not included in the reading workflow; inspect the page image in those cases. Bibliography extraction and registry matching can miss or misidentify entries.

A failed search means no match was found in the available extracted text, not that a concept is absent from the paper. Check the PDF directly before making that claim.

## Preserve notes and positions

Personal notes live under `~/.versofold/reading-desk/`; workspace notes live in `.versofold.reading.json`. Saves use revision checks. If another writer changes the record, retain your draft and reload or reconcile instead of overwriting silently.

Workspace memory remembers PDF position, zoom, the comparison paper and panel arrangement on this device. Disabling position restoration does not delete saved notes. See [Home & workspaces](workspaces.md).

Related: [check the sources](evidence.md), [references](references.md), [agent](agent.md).