The Python The Jarvis Build 🤖
Build your own AI assistant from an empty folder, in 12 chapters, with every step explained. It will remember your conversations, run code you wrote, read your own notes, and refuse to spend more than you allow. About 5 hours of work, and less than the price of a coffee in API costs.
Each chapter is 150 XP. Finishing all 12 unlocks the It's Alive achievement and the Jarvis milestone.
claude-haiku-4-5, the cheapest current model, at $1 per
million tokens in and $5 out. A hundred back-and-forth messages costs about twenty
cents. Chapter 12 adds a hard daily cap so it cannot quietly become more. Prices and
model names change; the chapters say so rather than pretending otherwise.
Part 1 Get it talking chapters 1 to 4
An assistant that answers you and remembers the conversation.
What You Are Building 🗺️
Understand the whole project before writing a line of it, including what it will cost.
Setting Up the Workshop 🧰
A project folder, an isolated environment, the SDK installed, and your API key stored where it cannot leak.
Hello, Jarvis 👋
Make your first API call and understand every single line of it.
A Conversation, Not a Goldfish 🧠
Turn a single question into a real back-and-forth that remembers what was said.
Part 2 Make it feel real chapters 5 to 7
Streaming, a character of its own, and memory that survives a restart.
Words as They Arrive ⚡
Make replies appear word by word instead of after an uncomfortable silence.
Giving Jarvis a Character 🎭
Use the system prompt to set behaviour, tone and honesty rules, and keep it in a file you can edit.
Remembering Between Runs 💾
Save the conversation to disk so closing the terminal does not wipe its memory.
Part 3 Give it hands chapters 8 to 10
Tools it can call, tools you wrote safely, and your own notes.
Giving Jarvis Hands 🔧
Understand the tool-use loop completely, and get your assistant calling its first real function.
Tools You Wrote, Safely 🛡️
Build a tool registry so adding abilities is easy, and a sandbox so they cannot be turned against you.
Jarvis Reads Your Notes 📚
Let your assistant answer from your own documents, and understand why this is searching rather than teaching.
Part 4 Make it yours chapters 11 to 12
A real installed command, a spending cap, and where to go next.
Not "an AI app". A while loop, a list, a dictionary of functions, a search, and a spending cap. Every AI agent you meet from now on, however impressive the marketing, is made of those parts. That is the actual point of this project: after it, none of this is mysterious.