Claude Code Go Module Development (2026)

Last updated: April 17, 2026

Go modules have become the standard for dependency management in Go projects. When paired with Claude Code’s AI capabilities, you can accelerate module development while maintaining code quality through automated testing and documentation workflows. This guide walks you through building production-ready Go modules with Claude Code, from initial setup through versioning, using specialized skills for testing, documentation, and project management.

Initializing Your Go Module

Start by creating a new Go module with proper initialization. The foundation of any Go module begins with a well-structured go.mod file:

mkdir myproject && cd myproject
go mod init github.com/yourusername/myproject

For projects requiring external dependencies, use semantic versioning in your go.mod:

module github.com/yourusername/myproject
go 1.21
require (
 github.com/stretchr/testify v1.8.4
 gopkg.in/yaml.v3 v3.0.1
)

Claude Code can help generate module structures automatically. When working on larger projects, consider using the tdd skill to establish test-driven development workflows from the start. Rather than asking Claude to “write a Go project,” be specific: describe the domain, the expected consumers of the module, and whether it’s a library, a CLI tool, or a service. This precision leads to better scaffold generation.

A note on Go workspace mode: if you’re developing multiple interdependent modules simultaneously, initialize a Go workspace to avoid replace directives in go.mod:

go work init ./moduleA ./moduleB

This is especially useful when you’re developing a shared library alongside the application that consumes it.

Structuring Your Module Architecture

A well-organized Go module follows Go conventions while maintaining clear separation of concerns. Here’s a practical project structure for a service-style module:

myproject/
 cmd/
 myproject/
 main.go
 internal/
 handlers/
 handler.go
 models/
 model.go
 services/
 service.go
 pkg/
 utils/
 utils.go
 go.mod
 go.sum
 Makefile

The cmd/ directory houses your application entry points, internal/ contains private application code that other modules cannot import, and pkg/ holds reusable packages others can import. This structure scales well for modules of any size.

The distinction between internal/ and pkg/ matters a great deal. Anything under internal/ is protected by Go’s toolchain, only code within the parent of the internal/ directory can import it. Use this to enforce architectural boundaries. For example, your HTTP handlers should not directly instantiate database connections; route that through a service layer in internal/services/.

When designing module APIs, think about backward compatibility. Use interfaces to define contracts between components, allowing internal implementations to change without breaking external consumers:

// OrderRepository defines the persistence contract for orders.
// Internal implementations can swap databases without changing callers.
type OrderRepository interface {
 Create(ctx context.Context, order Order) (string, error)
 FindByID(ctx context.Context, id string) (Order, error)
 ListByCustomer(ctx context.Context, customerID string, limit int) ([]Order, error)
}

Keep interfaces small and focused. The Go community idiom, accept interfaces, return structs, means your public functions should accept interface parameters but return concrete types. This keeps code flexible for callers without hiding useful type information.

Writing Testable Code

Go’s testing package provides everything needed for unit testing. Write tests alongside your code using table-driven patterns:

package services
import (
 "testing"
 "github.com/stretchr/testify/assert"
)
func TestCalculateTotal(t *testing.T) {
 tests := []struct {
 name string
 prices []float64
 expected float64
 }{
 {"empty slice", []float64{}, 0},
 {"single item", []float64{10.50}, 10.50},
 {"multiple items", []float64{10.00, 20.00, 30.00}, 60.00},
 {"with zero values", []float64{0.00, 5.00}, 5.00},
 {"negative values", []float64{-10.00, 20.00}, 10.00},
 }
 for _, tt := range tests {
 t.Run(tt.name, func(t *testing.T) {
 result := CalculateTotal(tt.prices)
 assert.Equal(t, tt.expected, result)
 })
 }
}

The tdd skill enhances this workflow by suggesting test cases, generating assertions, and identifying edge cases you might miss. It integrates smoothly with table-driven testing patterns common in Go projects. Ask Claude to review your test coverage by describing your function’s behavior and edge cases, and it will suggest additional rows for your test tables.

For code that depends on external systems, use mock interfaces rather than real connections in unit tests. The testify/mock package works well for this:

type MockOrderRepository struct {
 mock.Mock
}
func (m *MockOrderRepository) FindByID(ctx context.Context, id string) (Order, error) {
 args := m.Called(ctx, id)
 return args.Get(0).(Order), args.Error(1)
}
func TestOrderService_GetOrder(t *testing.T) {
 repo := new(MockOrderRepository)
 svc := NewOrderService(repo)
 expected := Order{ID: "123", Total: 99.99}
 repo.On("FindByID", mock.Anything, "123").Return(expected, nil)
 result, err := svc.GetOrder(context.Background(), "123")
 assert.NoError(t, err)
 assert.Equal(t, expected, result)
 repo.AssertExpectations(t)
}

For integration testing, use build tags to separate fast unit tests from slower integration suites:

//go:build integration
package services_test
import (
 "testing"
)
func TestOrderService_Integration(t *testing.T) {
 // Tests against a real database
}

Run integration tests explicitly with go test -tags integration ./... so they don’t slow down normal development cycles.

Documenting Your Module

Good documentation makes your module usable by others, and by your future self. Go provides documentation tooling built directly into the language through godoc:

// Package mathutil provides arithmetic utilities for financial calculations.
//
// The functions in this package handle precision-aware decimal
// arithmetic to avoid floating-point errors common in currency
// calculations.
//
// Example usage:
//
//	total := mathutil.Sum([]float64{10.00, 20.50, 5.25})
//	fmt.Printf("Total: %.2f\n", total) // Total: 35.75
package mathutil
// Sum returns the total of all values in the slice.
// Returns 0.0 for empty or nil slices. The function handles
// negative values correctly and is safe for concurrent use.
func Sum(values []float64) float64 {
 total := 0.0
 for _, v := range values {
 total += v
 }
 return total
}

Notice the example in the package doc comment, Go’s go test tool will execute any Example functions you write in test files and verify their output, making examples a form of tested documentation:

func ExampleSum() {
 total := Sum([]float64{10.00, 20.50, 5.25})
 fmt.Printf("%.2f", total)
 // Output: 35.75
}

Run go doc ./... to see rendered documentation for all packages. For more comprehensive documentation, the pdf skill can help generate formatted documentation files for distribution to teams that prefer static documents over browsing pkg.go.dev.

Managing Dependencies Effectively

Go modules handle dependency versions through go.mod and go.sum. Keep dependencies minimal and audit them regularly:

Check for outdated dependencies
go list -m -u all
Remove unused dependencies
go mod tidy
Verify checksums match the go.sum file
go mod verify
View the dependency graph
go mod graph | head -20

A common mistake is accumulating dependencies without justification. Before adding a new package, ask: could this be solved with the standard library? Go’s standard library is comprehensive, net/http, encoding/json, database/sql, crypto, and sync cover a significant percentage of real-world needs without pulling in external dependencies.

When you do need external packages, prefer modules that themselves have minimal transitive dependencies. Use go mod graph to understand the full closure of what you’re importing.

The supermemory skill can help track dependency decisions across multiple modules, making it easier to maintain consistency in larger projects. Store context about why you chose specific libraries and what alternatives you evaluated, so future team members understand the reasoning.

For vendoring dependencies (useful in air-gapped environments or for build reproducibility):

go mod vendor
go build -mod=vendor ./...

Building CLI Tools

Many Go modules expose command-line interfaces. Use the standard library’s flag package for simple CLIs or spf13/cobra for more complex multi-command tools:

package main
import (
 "flag"
 "fmt"
 "os"
)
func main() {
 verbose := flag.Bool("v", false, "verbose output")
 config := flag.String("c", "config.yaml", "config file path")
 output := flag.String("o", "stdout", "output destination: stdout, file, or s3://bucket/key")
 flag.Parse()
 if *verbose {
 fmt.Println("Running in verbose mode")
 }
 if err := run(*config, *output, *verbose); err != nil {
 fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 os.Exit(1)
 }
}
func run(configPath, outputDest string, verbose bool) error {
 cfg, err := loadConfig(configPath)
 if err != nil {
 return fmt.Errorf("loading config: %w", err)
 }
 _ = cfg
 return nil
}

Notice the use of fmt.Errorf with %w to wrap errors. This is idiomatic Go, it preserves the original error while adding context, and allows callers to use errors.Is and errors.As for type-checked error handling.

For cobra-based CLIs, the structure becomes more organized:

var rootCmd = &cobra.Command{
 Use: "myproject",
 Short: "A brief description of myproject",
 Long: `A longer description that spans multiple lines.`,
}
var importCmd = &cobra.Command{
 Use: "import [file]",
 Short: "Import data from a file",
 Args: cobra.ExactArgs(1),
 RunE: func(cmd *cobra.Command, args []string) error {
 return runImport(args[0])
 },
}
func init() {
 rootCmd.AddCommand(importCmd)
 importCmd.Flags().StringP("format", "f", "csv", "input format: csv, json, tsv")
}

When building CLIs, always return meaningful exit codes. Exit 0 for success, exit 1 for general errors, and exit 2 for usage errors (wrong flags, missing arguments). This matters for shell scripts that call your tool.

Comparing Dependency Management Approaches

Understanding the tradeoffs between Go module strategies helps you make better architectural decisions:

Approach	Best For	Tradeoff
Direct dependencies only	Simple tools, services	Fast builds, easy audits
Vendoring	Air-gapped builds, strict reproducibility	Larger repo size
Go workspace	Multi-module development	Only for local dev, not production
Replace directives	Forking a dependency temporarily	Must remove before release
Minimal version selection	Libraries others will import	Avoids version conflicts downstream

Go’s minimal version selection (MVS) algorithm means you always get the minimum version that satisfies all requirements, unlike npm’s behavior of installing the latest compatible version. This predictability is a significant advantage for long-running projects.

Versioning and Releases

Follow semantic versioning for Go modules. Use Git tags to mark releases:

Tag a release
git tag v1.2.3
git push origin v1.2.3
List available versions for a module
go list -m -versions github.com/example/pkg

Go’s module proxy at proxy.golang.org automatically caches module versions once they’re tagged. This means deleted or altered tags won’t affect consumers who already downloaded your module, a guarantee of stability.

For modules that have reached v2 or beyond, you must include the major version in the module path:

// In go.mod for a v2 module
module github.com/yourusername/myproject/v2
go 1.21

And importers must use the versioned import path:

import "github.com/yourusername/myproject/v2/pkg/utils"

This feels verbose but prevents silent breaking changes, consumers explicitly opt into major versions.

For pre-release versions, use the standard semver pre-release syntax:

git tag v1.3.0-beta.1
git tag v1.3.0-rc.1
git tag v1.3.0

Automating Workflows

Combine Claude Code skills for automated development workflows. Create a Makefile for common tasks:

.PHONY: test lint build docs coverage
test:
	go test -v -race -coverprofile=coverage.out ./...
test-integration:
	go test -v -race -tags integration ./...
lint:
	golangci-lint run ./...
	go vet ./...
build:
	go build -ldflags="-X main.version=$(git describe --tags)" -o bin/myproject ./cmd/myproject
docs:
	go doc -all ./... > docs/api.txt
coverage:
	go test -coverprofile=coverage.out ./...
	go tool cover -html=coverage.out -o coverage.html
clean:
	rm -rf bin/ coverage.out coverage.html

Notice the -ldflags="-X main.version=..." in the build target, this embeds the git tag as the version string in the binary at compile time, so myproject --version can report the exact release without reading a file at runtime.

The tdd skill can suggest improvements to your test coverage by analyzing which code paths are exercised. For documentation generation, the pdf skill converts Go docs into shareable formats suitable for team distribution or client handoffs.

Error Handling Patterns

Good Go modules handle errors consistently. Establish patterns early:

// Define sentinel errors for conditions callers need to check
var (
 ErrNotFound = errors.New("record not found")
 ErrPermission = errors.New("insufficient permissions")
)
// Use custom error types when callers need structured data
type ValidationError struct {
 Field string
 Message string
}
func (e *ValidationError) Error() string {
 return fmt.Sprintf("validation error on field %s: %s", e.Field, e.Message)
}
// Wrap errors with context at each layer
func (s *OrderService) GetOrder(ctx context.Context, id string) (Order, error) {
 order, err := s.repo.FindByID(ctx, id)
 if err != nil {
 return Order{}, fmt.Errorf("OrderService.GetOrder id=%s: %w", id, err)
 }
 return order, nil
}

Callers can then use errors.Is to check for sentinel errors and errors.As to extract typed errors, maintaining the full error chain for logging while still enabling programmatic error handling.

Conclusion

Building Go modules with Claude Code combines Go’s simplicity and performance with AI-assisted development. Focus on clean package design, comprehensive testing, and clear documentation from the start. Lean on interfaces to create architectural boundaries, use table-driven tests to cover edge cases thoroughly, and establish consistent error handling patterns before your codebase grows large enough to make refactoring painful. The skills ecosystem, including tdd, pdf, and supermemory, provides targeted assistance for different aspects of module development. Start with a solid foundation, ship working code quickly, and iterate based on actual usage patterns rather than speculation.

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