Architecture¶

Moo is one Spring Boot application organized by responsibility. Controllers own HTTP contracts, services own behavior, repositories own persistence, and model records define the public API.

flowchart TD
    Request --> Chain
    subgraph Chain[SecurityFilterChain]
        JwtRequestFilter --> UsernamePasswordAuthenticationFilter
    end
    Chain --> Controllers
    Controllers --> Services
    Services --> Repositories
    Repositories --> Entities
    Entities --> DB[(Database)]
    Controllers -. errors .-> Advice[ControllerExceptionHandler]

Package responsibilities¶

Package	Responsibility
`controller`	Versioned HTTP endpoints and validation
`service`	Business contracts and implementations
`repository`	Spring Data database access
`entity`	Internal JPA persistence state
`model`	Request and response records
`security`	JWT authentication and CSRF configuration
`config`	Framework integration and fallback errors
`exception`	API exception mapping

Authenticated operations derive the current user from Principal; callers cannot substitute another user ID. State-changing requests also pass Spring Security CSRF validation.

In this section¶

Page	Focus
Technology choices	Runtime, frameworks, persistence, observability, and quality tools
Data model	Users, posts, follows, likes, hashtags, and refresh tokens
API architecture	Versioned HTTP contracts, authentication, and response models