Muin

Explore a PDF’s internals in the editor — indirect objects, streams, page tree, and cross-references — as a navigable graph.

Usage

Install the Muin extension. Run Muin: Explore PDF from the Command Palette, or right-click a .pdf in the Explorer. Pick a file if one is not already selected. A tab titled Muin: <file> opens beside the editor.

The panel shows the current object’s neighborhood (incoming / current / outgoing refs), the object itself, and a command box.

• Click a neighbor, or a ref in the object pane, to cd.
• Tab / arrows / Enter / Esc move between the graph and the prompt, pick a neighbor, and complete commands.
• Any command other than cd / back (find, tree, check, help, history, cat, stream, …) opens its result in a panel over the graph. Close it with Esc or the panel’s close button.

Encrypted PDFs are not supported.

Copilot / MCP

Once the extension is installed, Copilot agent mode discovers Muin’s tools without editing mcp.json. The agent should call open on a workspace PDF (the path may be omitted to use the focused file: the active tab if it is a .pdf, otherwise the file already in the Muin panel). focused returns that path. close ends the session.

Commands

cd accepts O G R, O,G, a dictionary key (/Pages), or an array index.

Limits (defaults)

• Max input file: 200 MiB
• Max objects: 200_000
• Max structure JSON: 512 MiB (object graph only; stream bodies are not loaded at open)

License

MIT. Source: github.com/fasaled/muin