QR code generation

Bundled script: scripts/make_qr.py. It produces one consistent style so every QR in a deck, poster, or README looks the same, and it decodes every output back to catch broken codes before they land on a slide.

First-run setup

Ask once which Python interpreter to use (any env with qrcode[pil]; pyzbar or opencv-python optional for verification). Remember it as {PY} below.

pip install "qrcode[pil]" pyzbar     # or: pip install "qrcode[pil]" opencv-python

Run

PY={PY}
S=~/.claude/skills/qr-code/scripts/make_qr.py

$PY $S "https://catbench.org/"                          # -> ./qr_catbench_org.png
$PY $S "https://github.com/JinukMoon/CatBench" -o qr_catbench_github.png
$PY $S "tel:01012345678" -o qr_phone.png                 # phone numbers use tel:
$PY $S --batch links.txt -d assets/qr/                   # many at once

links.txt for batch mode — one per line, optional name<TAB>url (name becomes the filename):

qr_leaderboard	https://catbench.org/
qr_catbench_github	https://github.com/JinukMoon/CatBench
https://github.com/JinukMoon/oh-my-mlip

Options: --box N (module px, default 20 → 860 px image; use 10 for ~430 px), --no-frame (drop the black border), -d DIR (output folder).

Why these choices (so you can deviate sensibly)

• version 5 + ERROR_CORRECT_H: H-level correction survives partial occlusion (logo overlays, glare on a projector, a phone camera at an angle) — the situation a conference QR actually lives in. Version 5 comfortably holds any URL up to ~80 chars at H.
• box 20 + black frame: the frame gives a clean quiet-zone boundary on white slides and posters. Keep it unless the user asks for a borderless one.
• Decode verification: the script re-reads each PNG (pyzbar or OpenCV, whichever is installed) and exits non-zero on mismatch. Report the [OK verified] line to the user; if it prints no decoder installed, say so — don't claim verification you didn't get.

Workflow

1. Confirm the exact target strings. URLs: include the scheme (https://); phone: tel: + digits, no hyphens; plain text is fine too. If a URL is ambiguous (repo vs. website), ask once — a QR to the wrong page is worse than no QR.
2. Pick filenames that say what they point to (qr_leaderboard.png, not qr1.png) — decks accumulate many QRs and nobody can tell them apart visually.
3. Run the script; save into the project's asset folder (e.g. assets/qr/), not /tmp.
4. Paste the verification lines back to the user. If the QR is going on a slide, mention the size: 860 px renders crisp at 1.2–1.5 in; below ~1 in the modules get too fine for phones across a room.
5. If several QRs go on one slide, a caption under each (site name / repo name) is worth more than the URL text — people scan the one they want.

Dependencies

qrcode[pil] (required). Decoding uses pyzbar or opencv-python if present; absence only disables verification, not generation.