Agent
An AI wired up to take actions, not just produce words.
AI Conceptsadvanced
Dictionary
A working reference. Game mechanics, prompting craft, the quieter corners of how AI actually works.
Apprentice vs Builder path
Two entry points — new to AI, or already using it.
The Gamebasic
Chain of thought
Ask the model to think step by step. Accuracy goes up.
Promptingintermediate
Challenge
One screen of Mosaic — the atomic unit of progress.
The Gamebasic
Claude Code
Claude in your terminal. Reads, writes, and runs code on your actual machine.
Toolsintermediate
Claude.ai
Claude in your browser. No install, no card to start.
Toolsbasic
CLI
A program you control by typing. The opposite of a GUI.
Toolsbasic
Conditional
Code that runs only when a condition is true — the `if` statement.
Codebasic
Context
What the AI doesn't know yet but needs to. Give it that.
Promptingbasic
Context window
How much the AI can see at once. When it fills up, the early stuff gets forgotten.
AI Conceptsintermediate
Few-shot prompting
Show examples instead of explaining. The AI continues the pattern.
Promptingintermediate
Function
A reusable block of code that does a job when you call it.
Codebasic
Getting unstuck
You've hit a wall. Here's the sequence that usually works.
Guidesbasic
Git
Save points for your code. Undo, branching, collaboration.
Toolsintermediate
GitHub
Where your Git repositories live online. The social network for code.
Toolsintermediate
Hallucination
When the AI says something false with full confidence.
AI Conceptsintermediate
How Mosaic works
Three arcs, two starting paths, a real portfolio at the end.
The Gamebasic
Installing Claude Code
Getting Claude Code running on your machine. Arc II assumes this is done.
Guidesintermediate
Iteration
The AI's first answer is a draft. Treat it that way.
Promptingbasic
List
An ordered collection of values. Python's name for what some languages call an array.
Codebasic
LLM (Large Language Model)
The type of AI behind Claude, ChatGPT, and everything that feels like magic right now.
AI Conceptsintermediate
Loop
Code that runs multiple times — a `for` or `while` statement.
Codebasic
Model
A specific trained AI — like Claude Opus 4.7 or Claude Sonnet 4.6.
AI Conceptsbasic
Multimodal
An AI that can handle text plus images, audio, or video — not just typed input.
AI Conceptsintermediate
Output format
Tell the AI what shape you want. It will give you that shape.
Promptingbasic
Prompt
What you type to the AI. Everything downstream depends on it.
Promptingbasic
Python
Mosaic's language for most of Arc II. Clean syntax, widely used, beginner-friendly.
Codebasic
RAG (Retrieval-Augmented Generation)
Give the AI documents to look at before it answers. Fixes the "it doesn't know my stuff" problem.
AI Conceptsadvanced
Repository
A project folder being tracked by Git. Shortened to "repo."
Toolsintermediate
Role prompting
Give the AI a persona. It'll speak from that voice and depth.
Promptingbasic
Shell
The program inside the terminal that interprets your commands. Usually bash or zsh.
Toolsintermediate
Specificity
Saying exactly what you mean — the single biggest predictor of a useful response.
Promptingbasic
String
Text data. Anything between quotes.
Codebasic
Syntax error
Your code doesn't parse. The grammar is wrong.
Codebasic
System prompt
The invisible instruction that shapes how the AI behaves all conversation long.
Promptingintermediate
Temperature
A dial between predictable and random. 0 = rigid, 1 = creative.
AI Conceptsadvanced
Terminal
Where you type commands instead of clicking. Your computer's text interface.
Toolsbasic
The three arcs
Three stages: Foundations → Craft → Capstone.
The Gamebasic
Token
The unit the AI actually reads — roughly a word, often less.
AI Conceptsintermediate
Training data
The enormous pile of text the AI learned from — before you ever talked to it.
AI Conceptsintermediate
Variable
A named slot that holds a value. Everything else in code is built on these.
Codebasic
VS Code
Mosaic's recommended editor. Free, everywhere, works with everything.
Toolsbasic
When the AI gets it wrong
The response missed. Here's the order of operations to fix it.
Guidesbasic