Go Project

Purpose

Provide comprehensive analysis of Go projects to help new team members understand the codebase quickly. This skill leverages the go-specialist agent to analyze Go-specific patterns, idioms, and best practices.

When to Use

Use this skill when you need to:

• Onboard to a new Go project - Get a complete overview of the codebase structure
• Understand project architecture - Identify Clean Architecture, DDD, or hexagonal patterns
• Analyze dependencies - Review go.mod and understand external package usage
• Find entry points - Locate main.go files and cmd/ directory structure
• Review package organization - Understand internal/, pkg/, and module boundaries
• Examine test coverage - Analyze test file organization and testing patterns
• Generate dependency graphs - Create Mermaid diagrams showing package relationships
• Document the codebase - Generate onboarding documentation

Key Information

Go Project Structure Patterns

Standard Go Project Layout

project/
├── cmd/                    # Main applications (entry points)
│   ├── api/
│   │   └── main.go
│   └── worker/
│       └── main.go
├── internal/               # Private application code
│   ├── domain/            # Business logic
│   ├── repository/        # Data access
│   ├── service/           # Application services
│   └── handler/           # HTTP/gRPC handlers
├── pkg/                    # Public library code
├── api/                    # API definitions (OpenAPI, proto)
├── configs/               # Configuration files
├── scripts/               # Build and deployment scripts
├── test/                  # Additional test data
├── go.mod                 # Module definition
├── go.sum                 # Dependency checksums
└── Makefile              # Build commands

Analysis Checklist

When analyzing a Go project, examine:

1. Entry Points

   • cmd/ directory structure
   • main.go files and their initialization
   • Build tags and conditional compilation

2. Module Structure

   • go.mod - module path, Go version, dependencies
   • go.sum - verify dependency integrity
   • Replace directives for local development

3. Package Organization

   • internal/ - private packages not importable externally
   • pkg/ - public reusable packages
   • Package naming conventions and cohesion

4. Architecture Patterns

   • Clean Architecture layers (domain, usecase, interface, infrastructure)
   • DDD patterns (entities, value objects, aggregates, repositories)
   • Hexagonal/Ports & Adapters pattern

5. Code Quality

   • Concise and non-redundant implementation
   • Consistent coding conventions
   • Error handling patterns
   • Linting configuration (golangci-lint)

Analysis Commands

# Find all main.go files (entry points)
find . -name "main.go" -type f

# List all packages
go list ./...

# Show module dependencies
go mod graph

# Check for outdated dependencies
go list -u -m all

# Analyze test coverage
go test -cover ./...

# Find interfaces
grep -r "type.*interface" --include="*.go"

# Find structs
grep -r "type.*struct" --include="*.go"

Package Dependency Graph (Mermaid)

Generate a visual dependency graph in Mermaid format to understand package relationships.

Generating the Dependency Graph

# Get all package dependencies in graph format
go mod graph

# List internal package imports
go list -f '{{.ImportPath}} -> {{join .Imports ", "}}' ./...

Mermaid Output Format

Create a dependency-graph.md file with Mermaid diagrams. Use the reference templates in the reference/ folder:

• Internal Dependencies: See reference/internal-dependencies.mmd
• External Dependencies: See reference/external-dependencies.mmd
• Layer Architecture: See reference/layer-architecture.mmd

Example output structure:

# Package Dependency Graph

## Internal Package Dependencies

\`\`\`mermaid
<!-- Copy and adapt from reference/internal-dependencies.mmd -->
\`\`\`

## External Dependencies

\`\`\`mermaid
<!-- Copy and adapt from reference/external-dependencies.mmd -->
\`\`\`

Analysis Script

Use this bash script to extract package dependencies:

# Extract internal package dependencies
go list -f '{{.ImportPath}}|{{range .Imports}}{{.}}|{{end}}' ./... 2>/dev/null | while IFS='|' read -r pkg imports; do
  # Filter to show only internal imports
  module=$(go list -m)
  echo "$imports" | tr '|' '\n' | grep "^$module" | while read -r imp; do
    echo "    $(basename $pkg) --> $(basename $imp)"
  done
done

Output File Structure

When generating the dependency graph, create:

1. docs/dependency-graph.md - Main Mermaid diagram file
2. Include sections for:
   • Internal package dependencies (flowchart)
   • External dependencies (list with versions)
   • Layer/architecture visualization
   • Circular dependency warnings (if any)

Layer-based Visualization

For Clean Architecture or layered projects, use the template in reference/layer-architecture.mmd.

This template visualizes:

• Presentation Layer (HTTP Handlers, Middleware)
• Application Layer (Use Cases, Services)
• Domain Layer (Entities, Repository Interfaces)
• Infrastructure Layer (Database, Cache, External APIs)

Output Format

Generate an onboarding report with:

1. Project Overview

   • Module name and Go version
   • Purpose and main functionality
   • Key entry points

2. Architecture Summary

   • Identified patterns
   • Layer organization
   • Key abstractions

3. Dependency Analysis

   • Critical external dependencies
   • Internal package graph
   • Third-party framework usage

4. Package Dependency Graph (Mermaid file output)

   • Generate docs/dependency-graph.md with Mermaid diagrams
   • Internal package relationships
   • External dependency visualization
   • Architecture layer diagram

5. Development Guide

   • How to build and run
   • Testing approach
   • Configuration requirements

6. Key Files to Read

   • Recommended reading order
   • Critical files for understanding the system

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