# Cairo Contract Classes

> Explain Starknet contract classes vs instances, class hash, contract deployment, and upgrade patterns; use when a request involves declaring/deploying contracts or understanding class hashes in Cairo.

- Skill: `teddyjfpender/cairo-contract-classes` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add teddyjfpender/cairo-contract-classes`
- Raw SKILL.md: https://api.skillmd.com/api/skills/teddyjfpender/cairo-contract-classes/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: teddyjfpender (https://skillmd.com/u/teddyjfpender)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/teddyjfpender/cairo-contract-classes

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# Cairo Contract Classes and Instances

## Overview
Clarify what a contract class is, how instances are deployed, and how class hashes relate to code and ABI.

## Quick Use
- Read `references/contract-classes.md` before answering.
- Distinguish class (code + ABI) from instance (storage + address).
- Mention class hash and contract address derivation when deployment is discussed.

## Response Checklist
- Use "class" for the compiled contract definition and "instance" for a deployed contract.
- Note that a class is immutable; upgrades require a proxy pattern.
- Mention declare vs deploy and when each step is required.

## Example Requests
- "What is the difference between a class and a contract instance?"
- "How is a contract address computed?"
- "Why do I need to declare before deploying?"