ian-q/napkin

A throwaway sketch window for showing an AI coding agent what you mean.

Press a hotkey. An Excalidraw window opens, with any images you just copied already on it. Crop them, arrange them, circle the bit you mean in red. Press Done (⌘↵): the window closes and a small, flattened JPEG is on your clipboard, ready to paste into your prompt.

Watch the 20-second video, with sound

yeah that makes sense, but for this airfoil I was thinking we have it
a bit more rounded here, kinda like this: [Image #1]

• One hotkey. Tap it for a new canvas; hold it for your history.
• What you copied is already there. Select photos in Finder (HEIC straight off AirDrop is fine), copy, tap the hotkey.
• Small on purpose. The export is at most 2000 px, Lanczos-resampled: what costs tokens is pixels, so you don’t pay for a 12 MP photo of a whiteboard.
• Your agent can draw back. Every image carries a stamp (napkin nk-0042) that points at the editable canvas. An agent that isn’t sure what you meant circles its guess on your sketch and pops the window back up for you.
• Local. A small server on 127.0.0.1 and a chromeless browser window. Nothing leaves your machine.

Install

Needs bun, ImageMagick 7 and a Chromium-family browser (Chrome, Brave, Chromium, Edge or Vivaldi). macOS is the tested platform; Linux should work with wl-clipboard or xclip installed but has not been tested.

curl -fsSL https://raw.githubusercontent.com/Ian-q/napkin/main/install.sh | bash

That clones napkin into ~/.local/share/napkin/src, offers to install bun and ImageMagick with Homebrew if they are missing, builds it, links ~/.local/bin/napkin, and asks three things:

1. The hotkey. The default on macOS is a built-in ctrl+option+n: a tiny background helper (compiled on the spot with Swift from Xcode’s command line tools; xcode-select --install if you have never needed them) that needs no Accessibility permission. Or a line in skhd, or none.
2. The Claude Code skill, which teaches agents to read napkins and draw on them.