PDF Viewer plugin (mark up, number pages, build forms, ask, compare)

What it is

The PDF Viewer is a plugin for Omniscio. It opens a PDF file that is already on your computer, shows it page by page, and lets you mark it up and edit it.

It is a different thing from Omniscio's built-in PDF preview. That preview opens when you click a PDF in a chat or in the file list. The plugin is a separate pane you open yourself.

Three ideas explain how it behaves:

• It only adds to the end of the file. Saving never rewrites the bytes the file started with. So a save is small, and the original is always still inside the file.
• Nothing changes the file unless a person does it on purpose. An agent can ask for a change, but the change waits until a person saves.
• Your marks live beside the file. Highlights, notes, drawings and the rest are kept by the plugin. They go into the file only when you press Save marks into this PDF.

Where to find it

• Get it from the plugin Marketplace (Settings → Plugins → Browse Marketplace). Then open PDF Viewer in the sidebar and pick a file.
• The … menu at the top of the pane holds the bigger actions, in groups: Turn this page, Merge a PDF in…, Page numbers and headers…, Build a form, Highlight every mention, Save marks into this PDF, Compare with a PDF…, Print this page and Ask the document. Some rows appear only once they can act; others are greyed out and say why.
• The marking tools sit in a dock at the bottom of the page: Draw, Box a region, Place note, Text box, Picture, Stamp, Sign, Undo and Delete mark. Highlight, Underline and Strike out appear next to text when you select it.
• The Bookmarks button in the top bar opens the file's own table of contents.
• The Page Rail beside the page lists every page, each with a small picture of it.

How it behaves

Put your marks into the PDF so other apps show them

Press Save marks into this PDF in the … menu. The plugin writes a copy of every mark into the file as a real PDF annotation, then saves. Acrobat, Preview and other PDF apps can then show your marks.

• Your marks stay editable here. Change one and press again to update the file.
• Pressing again with nothing changed adds nothing.
• One Undo takes the press back.
• A mark that cannot be written is named and left out. Examples: a mark on a page you have turned since, words the built-in font cannot show, or a picture that is no longer kept.
• One press writes at most 8 MiB of new pictures. Press again to write the rest.
• Only your press does this. An agent, the AI, or an ordinary save never writes marks into the file.
• A signed PDF asks you first.
• Limit: once a mark is saved into the file, it stays in the file's history even after you remove it. Saving only ever adds to the end.
• Limit: a press from an earlier sitting cannot be undone. The plugin says so.

Add a text box, picture, stamp or signature

Pick Text box, Picture, Stamp or Sign in the dock, fill in what it carries, then tap the page.

• A text box holds your words. A picture is a PNG or JPEG of at most 4 MB. A stamp is Approved, Draft, Confidential, Received, or a short line of your own words.
• A signature is your name in a slanted typeface, or a picture of your signature. You can also draw it with the pen. It is not a digital signature and proves nothing about who placed it.
• Only you can place a signature. An agent cannot place any of these four.
• Letters the built-in font cannot show are refused by name before anything is placed.

Find your way around a long PDF

• Thumbnails: each Page Rail entry shows a small picture of its page. They draw while you scroll and never slow down reading, marking or searching.
• Bookmarks: the Bookmarks panel shows the file's own table of contents. Click an entry to jump to it. A broken entry is shown greyed, with the reason. A file with no table of contents says so.
• Keys: Cmd/Ctrl+F jumps to search. Page Up and Page Down turn the page. Home and End jump to the first and last page. The arrow keys turn the page once the page itself has focus (click it, or Tab to it). No key fires while you are typing in a box.

Open a password-protected PDF

Pick the file, type its password, and press Unlock. A wrong password says so and lets you try again. Cancel leaves the pane exactly as it was. A PDF opened with a password is read-only. A PDF that needs no password never asks for one.

Print

Print this page prints the page on screen, with its marks, through your computer's own print dialog. Only the page, its marks and its page numbers or headers print — never a menu or a panel. Printing changes nothing in the file. Printing the whole document is not offered yet.

Add page numbers, headers, footers, watermarks or Bates numbers

Choose Page numbers and headers… in the … menu. Pick what to write, where it goes, and which pages, then press the button. The button shows how many pages it will write on.

• These words become part of the page, so every PDF app shows them. The plugin calls them Imprints.
• Page numbers come in four styles, such as "3", "Page 3" and "Page 3 of 12". Bates numbers are a prefix and a counter, such as "ABC000123".
• They sit at the edge you see, even on a turned or cropped page. A watermark runs across the middle.
• One press is one change and one Undo, however many pages it covers.
• The plugin can remove its own Imprints later, even after you reopen the file. It never removes words another app wrote.
• Only Western European letters can be written. Any other letter is named and refused before anything is written.
• A signed PDF is warned about first. There is no Stop button, because one press is one change and saving is fast: about 3 seconds for 4,000 pages.

Ask about a PDF, summarize it, or translate it

Choose Ask the document in the … menu. Pick the pages, then Summarize, Ask a question, or Translate into a language you choose. This needs AI set up in Omniscio; without it the row is greyed out and says what is missing.

• The pages being sent are always shown before anything is sent.
• None of this changes the file. Closing the panel forgets the conversation.
• An answer points to the pages it used. A checked quote highlights the words when you click it. A quote the page does not carry is marked as not checked.
• Pages with no readable text, such as a scan with no text layer, are refused rather than answered.
• A long translation runs in parts, shows its progress, and can be stopped between parts.

Build a form

Choose Build a form in the … menu. Draw a box on the page, or tap for a box of the usual size. Choose the kind of field (text, check box, radio group, dropdown or signature), give it a name, and press Add field.

• The field is written into the PDF, so other PDF apps show it before anyone fills it.
• You, or your agent, can fill it straight away.
• You can move, resize or delete a field you added, by mouse, finger or keyboard. Fields the form came with are left alone.
• Two fields never share a name. A taken name is refused and a free one is offered.
• One Undo takes back one action. Undoing the first field on a PDF that had no form removes the form too.
• A signed form, or one with an extra Acrobat-only layer, asks you first. An encrypted PDF, or one opened read-only, cannot be changed.
• The page picture shows the form as it was when the file opened, so a new or moved field is drawn as an outline until you open the file again.

Compare two PDFs

Choose Compare with a PDF… and pick the second file. The plugin lists the words added, removed or changed, page by page, and draws boxes around them. Click a result to jump to its page.

• Comparing never writes to either file. To keep one difference, press its Keep as mark button. That adds an ordinary mark.
• Different page counts are lined up first, so an inserted or removed page is named.
• A page that cannot be read is listed, not skipped.
• A long comparison can be stopped at any time and keeps what it found.
• Compare page images too is an optional second pass. It finds pages that look different even when their words match. It says how long it may take before you start it.
• If you change the pages meanwhile (turn, crop, move, insert or delete a page, or write page numbers or a field), the comparison is marked out of date and offers nothing to keep. Adding a mark does not do this.

For agents

• Code and rules: the plugin is src/plugins/pdf-viewer/. What must stay true is .claude/memory/contracts/pdf-viewer-plugin-editing-contract.md; how it is built, and which test locks each rule, is .claude/memory/pdf-viewer-plugin-map.md. Decisions are the plugin's ADRs 0042 to 0049 in src/plugins/pdf-viewer/docs/adr/, and its glossary is src/plugins/pdf-viewer/CONTEXT.md.
• Agent routes: POST /plugins/pdf-viewer/cli/query reads an open Document, and POST /plugins/pdf-viewer/cli/edit asks for an Edit. Both need the pane open, which only a person can do.
• What an agent's edit can add: besides the page and mark Operations it already had, it can fill form fields, including ones a person just built, and add an Imprint with addImprint, placed by an edge. Every agent Edit waits in memory until a person saves.
• What it cannot do: save marks into the file, place a text box, picture, stamp or signature, build or delete form fields, or remove an Imprint.

Related

• Plugin Marketplace — how to find, install and update plugins such as this one.
• Peek Viewer — Omniscio's built-in preview, which also opens PDFs but is not this plugin.
• Plugin Bridge Capabilities — the host features a plugin like this one is allowed to call, including reading and saving a file you picked.