SOLID Java - Modular Architecture
Agent Workflow (MANDATORY)
Before ANY implementation, use TeamCreate to spawn 3 agents:
- fuse-ai-pilot:explore-codebase - Analyze existing architecture
- fuse-ai-pilot:research-expert - Verify Java docs via Context7
- fuse-ai-pilot:sniper - Post-implementation validation
DRY - Reuse Before Creating (MANDATORY)
Before writing ANY new code:
- Grep the codebase for similar interfaces, services, or logic
- Check shared locations:
modules/core/services/,modules/core/interfaces/ - If similar code exists -> extend/reuse instead of duplicate
- If code will be used by 2+ features -> create it in
modules/core/
Architecture (Modules MANDATORY)
| Layer | Location | Max Lines | |-------|----------|-----------| | Controllers | modules/[feature]/controllers/ | 50 | | Services | modules/[feature]/services/ | 100 | | Repositories | modules/[feature]/repositories/ | 100 | | Interfaces | modules/[feature]/interfaces/ | 30 | | Models/DTOs | modules/[feature]/models/ | 50 | | Shared | modules/core/{services,interfaces,models}/ | - |
NEVER use flat src/ structure - always modules/[feature]/
Critical Rules (MANDATORY)
| Rule | Value | |------|-------| | File limit | 100 lines (split at 90) | | Controllers | < 50 lines, delegate to services | | Interfaces | modules/[feature]/interfaces/ ONLY | | Javadoc | Every public method documented | | Records | Use for DTOs (Java 16+) | | Sealed | Use for restricted hierarchies (Java 17+) |
Reference Guide
Concepts
| Topic | Reference | When to consult | |-------|-----------|-----------------| | SOLID Overview | [solid-principles.md](references/solid-principles.md) | Quick reference | | SRP | [single-responsibility.md](references/single-responsibility.md) | Fat classes | | OCP | [open-closed.md](references/open-closed.md) | Adding providers | | LSP | [liskov-substitution.md](references/liskov-substitution.md) | Contracts | | ISP | [interface-segregation.md](references/interface-segregation.md) | Fat interfaces | | DIP | [dependency-inversion.md](references/dependency-inversion.md) | Injection | | Architecture | [architecture-patterns.md](references/architecture-patterns.md) | Modular patterns |
Templates
| Template | When to use | |----------|-------------| | [module.md](references/templates/module.md) | Feature module structure | | [service.md](references/templates/service.md) | Business logic service | | [interface.md](references/templates/interface.md) | Contract definition | | [repository.md](references/templates/repository.md) | Data access layer | | [error.md](references/templates/error.md) | Custom exceptions | | [test.md](references/templates/test.md) | Unit tests with mocks |
Forbidden
| Anti-Pattern | Fix | |--------------|-----| | Files > 100 lines | Split at 90 | | Interfaces in impl files | Move to interfaces/ directory | | new ConcreteClass() in services | Use dependency injection | | Flat src/ structure | Use modules/[feature]/ | | God classes | Split by responsibility |