Building an AI Agent Harness from Scratch

Two halves of one project.

.
├── frontend/   # Nuxt 4 + Nuxt UI v4 + Nuxt Content v3 — reads the book in a browser
└── harness/    # Python 3.11+ agent harness — the code the book teaches you to build

frontend

The manuscript lives in frontend/content/2.chapters/*.md and renders as a browsable site with a sidebar nav, TOC, and prev/next surround.

cd frontend
npm install
npm run dev          # http://localhost:3000

Theme: amber primary, zinc neutral. Dark mode toggle in the header.

harness

Python scaffold mirroring the structure the book builds, chapter by chapter. Every .py file under src/harness/ is a stub pointing at the chapter that implements it; the canonical consolidated arun and async Tool.arun helpers live in Appendix F of the book.

cd harness
uv sync
uv run pytest -q

See harness/README.md for the full module map.