solid-java ยท diff
git:20260927.43a351c to git:20261012.499a4d1
13 added, 13 removed. Audit A to A.
---
name: solid-java
- description: "Use when writing or refactoring Java code, structuring modules/[feature]/ layers, or defining interfaces/ contracts (SOLID, files < 100 lines)."
+ description: "Use when writing or refactoring Java code, structuring modules/[feature]/ layers, or defining interfaces/ contracts (SOLID, files within FUSE_SOLID_MAX_LINES)."
versions:
java: "25"
user-invocable: true
references: references/solid-principles.md, references/single-responsibility.md, references/open-closed.md, references/liskov-substitution.md, references/interface-segregation.md, references/dependency-inversion.md, references/architecture-patterns.md, references/templates/module.md, references/templates/service.md, references/templates/interface.md, references/templates/repository.md, references/templates/error.md, references/templates/test.md
related-skills: solid-detection
---
<objective>
- SOLID Java enforces a modular architecture for Java 25+ (current LTS): every feature lives under `modules/[feature]/` (controllers, services, repositories, interfaces, models/DTOs) with shared code in `modules/core/`, interfaces live only in `modules/[feature]/interfaces/`, controllers stay under 50 lines and delegate to services, records are used for DTOs and sealed types for restricted hierarchies, and every public method carries Javadoc.
+ SOLID Java enforces a modular architecture for Java 25+ (current LTS): every feature lives under `modules/[feature]/` (controllers, services, repositories, interfaces, models/DTOs) with shared code in `modules/core/`, interfaces live only in `modules/[feature]/interfaces/`, controllers stay thin and delegate to services, with files within `FUSE_SOLID_MAX_LINES`, records are used for DTOs and sealed types for restricted hierarchies, and every public method carries Javadoc.
Before writing any new code it requires a DRY check against `modules/core/services` and `modules/core/interfaces`. See `solid-principles.md` for the overview, the per-principle references for SRP/OCP/LSP/ISP/DIP detail, and the templates for module/service/interface/repository/error/test scaffolding.
</objective>
# SOLID Java - Modular Architecture
## Agent Workflow (MANDATORY)
Before ANY implementation, spawn 3 agents in parallel, one `Agent` call each with a `name`:
1. **fuse-ai-pilot:explore-codebase** - Analyze existing architecture
2. **fuse-ai-pilot:research-expert** - Verify Java docs via Context7
3. **fuse-ai-pilot:sniper** - Post-implementation validation
---
## DRY - Reuse Before Creating (MANDATORY)
**Before writing ANY new code:**
1. **Grep the codebase** for similar interfaces, services, or logic
2. Check shared locations: `modules/core/services/`, `modules/core/interfaces/`
3. If similar code exists -> extend/reuse instead of duplicate
4. 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}/` | - |
+ | Layer | Location |
+ |-------|----------|
+ | Controllers | `modules/[feature]/controllers/` |
+ | Services | `modules/[feature]/services/` |
+ | Repositories | `modules/[feature]/repositories/` |
+ | Interfaces | `modules/[feature]/interfaces/` |
+ | Models/DTOs | `modules/[feature]/models/` |
+ | 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 |
+ | File limit | `FUSE_SOLID_MAX_LINES` |
+ | Controllers | Thin, 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 |
+ | Files over `FUSE_SOLID_MAX_LINES` | Split by responsibility |
| 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 |