/solid-go

name: solid-go
description: "Use when writing or refactoring Go code, structuring internal/modules/[feature]/ layers, or defining ports/ interfaces (SOLID, files within FUSE_SOLID_MAX_LINES)."
versions:
  go: "1.27"
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/handler.md, references/templates/error.md, references/templates/test.md
related-skills: solid-detection

<objective> SOLID Go enforces a modular architecture for Go 1.27+: every feature lives under `internal/modules/[feature]/` (handlers, services, repositories, ports, models) with shared code in `internal/core/`, interfaces (ports) live only in `ports/` directories and stay small (1-3 methods, the Go idiom), functions accept interfaces but return structs, and every exported function carries a godoc comment.

Before writing any new code it requires a DRY check against `internal/core/services` and `internal/core/ports`. See `solid-principles.md` for the overview, the per-principle references for SRP/OCP/LSP/ISP/DIP detail, `architecture-patterns.md` for hexagonal/modular layout, and the templates for module/service/interface/handler/error/test scaffolding. </objective>

SOLID Go - 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 Go docs via Context7 3. **fuse-ai-pilot:sniper** - Post-implementation validation

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DRY - Reuse Before Creating (MANDATORY)

**Before writing ANY new code:** 1. **Grep the codebase** for similar interfaces, services, or logic 2. Check shared locations: `internal/core/services/`, `internal/core/ports/` 3. If similar code exists -> extend/reuse instead of duplicate 4. If code will be used by 2+ features -> create it in `internal/core/`

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Architecture (Modules MANDATORY)

| Layer | Location | |-------|----------| | Handlers | `internal/modules/[feature]/handlers/` | | Services | `internal/modules/[feature]/services/` | | Repositories | `internal/modules/[feature]/repositories/` | | Ports (interfaces) | `internal/modules/[feature]/ports/` | | Models | `internal/modules/[feature]/models/` | | Shared | `internal/core/{services,ports,models}/` |

**NEVER use flat `internal/` structure - always `internal/modules/[feature]/`**

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Critical Rules (MANDATORY)

| Rule | Value | |------|-------| | File limit | `FUSE_SOLID_MAX_LINES` | | Handlers | Thin, delegate to services | | Interfaces | `ports/` directory ONLY | | Godoc | Every exported function documented | | Accept interfaces | Return structs | | Small interfaces | 1-3 methods max (Go idiom) |

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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 structs | | **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) | Hex/modular |

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) | Port definition | | [handler.md](references/templates/handler.md) | HTTP handler | | [error.md](references/templates/error.md) | Custom errors | | [test.md](references/templates/test.md) | Table-driven tests |

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Forbidden

| Anti-Pattern | Fix | |--------------|-----| | Files over `FUSE_SOLID_MAX_LINES` | Split by responsibility | | Interfaces in impl files | Move to `ports/` directory | | Fat interfaces (4+ methods) | Split into small interfaces | | Flat `internal/` structure | Use `internal/modules/[feature]/` | | `init()` for dependency wiring | Use constructor injection |