pi-from-scratch hit 1,057 stars in nine days teaching a 600-line coding agent line by line.

SaladDay/pi-from-scratch rebuilds the pi agent's data flow as "nano-pi," ~600 lines of TypeScript that reads files, edits code, and runs commands. The companion site pairs prose with a right-hand editor filling in source as you read, plus a pre-generated Trace view letting you step through execution without making any model calls. Runs against any OpenAI-compatible endpoint on Node 22+. Over 100 stars/day sustained for a tutorial repo says agent-harness internals are still the thing developers most want demystified.