Architecture — CodeSensei Teaching Module

What is Architecture?

• Analogy: Architecture is the floor plan of your application. Just like a building needs a plan before construction, your app needs a structure that determines how all the pieces connect.
• Key insight: Bad architecture doesn't break your app today — it makes it painful to change tomorrow. Good architecture makes change easy.

Client-Server Architecture

• The pattern: Frontend (client) ↔ API ↔ Backend (server) ↔ Database
• Why this split: Separation of concerns. The frontend handles display, the backend handles logic and data. They can change independently.
• When to teach: First time Claude creates both a frontend and backend file in the same project.

Monolith vs Microservices

• Monolith: Everything in one codebase. Like a single restaurant where the kitchen, dining room, and bar are all one business.
• Microservices: Each feature is its own mini-app. Like a food court where each stall is independent.
• Key insight for vibecoders: Start monolith. Always. Microservices are for when you have scaling problems, not before.

MVC Pattern

• Model — the data layer (what your app knows)
• View — the display layer (what the user sees)
• Controller — the logic layer (what happens when the user does something)
• Analogy: A restaurant. The menu (model) has the dishes. The table presentation (view) is what the customer sees. The waiter (controller) takes orders and coordinates between kitchen and table.

State Management

• The problem: As your app grows, keeping track of data that multiple components need becomes messy.
• Analogy: In a small office, everyone shouts across the room. In a big company, you need an organized messaging system (Slack, email).
• Solutions: React Context, Redux, Zustand — all solve the same problem differently.

Caching

• Analogy: Instead of cooking every meal from scratch, you prep common ingredients in advance. Caching stores frequently-used data closer to where it's needed so you don't have to fetch it every time.

Authentication vs Authorization

• Authentication: "Who are you?" (login)
• Authorization: "What are you allowed to do?" (permissions)
• Analogy: Authentication is the bouncer checking your ID. Authorization is the VIP list determining which areas you can access.

When to Teach Architecture

• Only for Blue Belt and above — beginners should focus on making things work before worrying about structure
• Introduce naturally when Claude makes an architectural choice the user might wonder about