Anti-cheat engineering beta
Start Courier Lab.
The ten-unit course runs a local Node.js server. Download and extract the beta, open a terminal in its courier-lab folder, then run npm start with Node.js 22 or later. Open the full /learn URL printed in the terminal.
Download Courier Lab beta (.zip)
Guided decisions work at phone widths. Full source editing and HTTP tests need a workstation. Human learning, duration and native accessibility remain unvalidated. This is an owned toy-game teaching system, not production security.