A free, open-source textbook on building AI agents is GitHub’s #1 trending repo

“Understanding AI Agents: Design Principles and Engineering Practice” by Li Bojie topped GitHub’s trending list on July 21, 2026, adding over 4,000 stars in a day. The Apache-2.0 book ships 10 chapters and 88 runnable experiments across agent memory, retrieval, tools, coding agents, evaluation, and multi-agent systems, with PDF and EPUB editions in five languages including English.

What it means A free, code-backed curriculum for agent engineering — usable today by teams standardizing how they build and teach agents.