feat: add comprehensive Golang language support

Add Go-specific agents, skills, and commands for idiomatic Go development:

Agents:
- go-reviewer: Go code review for concurrency, error handling, security
- go-build-resolver: Fix Go build errors with minimal changes

Skills:
- golang-patterns: Idiomatic Go patterns, best practices, conventions
- golang-testing: TDD, table-driven tests, benchmarks, fuzzing

Commands:
- /go-review: Invoke Go code reviewer
- /go-test: Go TDD workflow with coverage
- /go-build: Fix Go build/vet/lint errors

Also updates README.md to document the new Go support.

README.md

@@ -4,6 +4,7 @@
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
 ![Shell](https://img.shields.io/badge/-Shell-4EAA25?logo=gnu-bash&logoColor=white)
 ![TypeScript](https://img.shields.io/badge/-TypeScript-3178C6?logo=typescript&logoColor=white)
+![Go](https://img.shields.io/badge/-Go-00ADD8?logo=go&logoColor=white)
 ![Markdown](https://img.shields.io/badge/-Markdown-000000?logo=markdown&logoColor=white)
 
 **The complete collection of Claude Code configs from an Anthropic hackathon winner.**
@@ -101,6 +102,8 @@ everything-claude-code/
 |   |-- e2e-runner.md        # Playwright E2E testing
 |   |-- refactor-cleaner.md  # Dead code cleanup
 |   |-- doc-updater.md       # Documentation sync
+|   |-- go-reviewer.md       # Go code review (NEW)
+|   |-- go-build-resolver.md # Go build error resolution (NEW)
 |
 |-- skills/           # Workflow definitions and domain knowledge
 |   |-- coding-standards/           # Language best practices
@@ -114,6 +117,8 @@ everything-claude-code/
 |   |-- security-review/            # Security checklist
 |   |-- eval-harness/               # Verification loop evaluation (Longform Guide)
 |   |-- verification-loop/          # Continuous verification (Longform Guide)
+|   |-- golang-patterns/            # Go idioms and best practices (NEW)
+|   |-- golang-testing/             # Go testing patterns, TDD, benchmarks (NEW)
 |
 |-- commands/         # Slash commands for quick execution
 |   |-- tdd.md              # /tdd - Test-driven development
@@ -125,7 +130,10 @@ everything-claude-code/
 |   |-- learn.md            # /learn - Extract patterns mid-session (Longform Guide)
 |   |-- checkpoint.md       # /checkpoint - Save verification state (Longform Guide)
 |   |-- verify.md           # /verify - Run verification loop (Longform Guide)
-|   |-- setup-pm.md         # /setup-pm - Configure package manager (NEW)
+|   |-- setup-pm.md         # /setup-pm - Configure package manager
+|   |-- go-review.md        # /go-review - Go code review (NEW)
+|   |-- go-test.md          # /go-test - Go TDD workflow (NEW)
+|   |-- go-build.md         # /go-build - Fix Go build errors (NEW)
 |
 |-- rules/            # Always-follow guidelines (copy to ~/.claude/rules/)
 |   |-- security.md         # Mandatory security checks
@@ -353,7 +361,7 @@ Please contribute! See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines.
 
 ### Ideas for Contributions
 
-- Language-specific skills (Python, Go, Rust patterns)
+- Language-specific skills (Python, Rust patterns) - Go now included!
 - Framework-specific configs (Django, Rails, Laravel)
 - DevOps agents (Kubernetes, Terraform, AWS)
 - Testing strategies (different frameworks)

agents/go-build-resolver.md

@@ -0,0 +1,368 @@
+---
+name: go-build-resolver
+description: Go build, vet, and compilation error resolution specialist. Fixes build errors, go vet issues, and linter warnings with minimal changes. Use when Go builds fail.
+tools: ["Read", "Write", "Edit", "Bash", "Grep", "Glob"]
+model: opus
+---
+
+# Go Build Error Resolver
+
+You are an expert Go build error resolution specialist. Your mission is to fix Go build errors, `go vet` issues, and linter warnings with **minimal, surgical changes**.
+
+## Core Responsibilities
+
+1. Diagnose Go compilation errors
+2. Fix `go vet` warnings
+3. Resolve `staticcheck` / `golangci-lint` issues
+4. Handle module dependency problems
+5. Fix type errors and interface mismatches
+
+## Diagnostic Commands
+
+Run these in order to understand the problem:
+
+```bash
+# 1. Basic build check
+go build ./...
+
+# 2. Vet for common mistakes
+go vet ./...
+
+# 3. Static analysis (if available)
+staticcheck ./... 2>/dev/null || echo "staticcheck not installed"
+golangci-lint run 2>/dev/null || echo "golangci-lint not installed"
+
+# 4. Module verification
+go mod verify
+go mod tidy -v
+
+# 5. List dependencies
+go list -m all
+```
+
+## Common Error Patterns & Fixes
+
+### 1. Undefined Identifier
+
+**Error:** `undefined: SomeFunc`
+
+**Causes:**
+- Missing import
+- Typo in function/variable name
+- Unexported identifier (lowercase first letter)
+- Function defined in different file with build constraints
+
+**Fix:**
+```go
+// Add missing import
+import "package/that/defines/SomeFunc"
+
+// Or fix typo
+// somefunc -> SomeFunc
+
+// Or export the identifier
+// func someFunc() -> func SomeFunc()
+```
+
+### 2. Type Mismatch
+
+**Error:** `cannot use x (type A) as type B`
+
+**Causes:**
+- Wrong type conversion
+- Interface not satisfied
+- Pointer vs value mismatch
+
+**Fix:**
+```go
+// Type conversion
+var x int = 42
+var y int64 = int64(x)
+
+// Pointer to value
+var ptr *int = &x
+var val int = *ptr
+
+// Value to pointer
+var val int = 42
+var ptr *int = &val
+```
+
+### 3. Interface Not Satisfied
+
+**Error:** `X does not implement Y (missing method Z)`
+
+**Diagnosis:**
+```bash
+# Find what methods are missing
+go doc package.Interface
+```
+
+**Fix:**
+```go
+// Implement missing method with correct signature
+func (x *X) Z() error {
+    // implementation
+    return nil
+}
+
+// Check receiver type matches (pointer vs value)
+// If interface expects: func (x X) Method()
+// You wrote:           func (x *X) Method()  // Won't satisfy
+```
+
+### 4. Import Cycle
+
+**Error:** `import cycle not allowed`
+
+**Diagnosis:**
+```bash
+go list -f '{{.ImportPath}} -> {{.Imports}}' ./...
+```
+
+**Fix:**
+- Move shared types to a separate package
+- Use interfaces to break the cycle
+- Restructure package dependencies
+
+```
+# Before (cycle)
+package/a -> package/b -> package/a
+
+# After (fixed)
+package/types  <- shared types
+package/a -> package/types
+package/b -> package/types
+```
+
+### 5. Cannot Find Package
+
+**Error:** `cannot find package "x"`
+
+**Fix:**
+```bash
+# Add dependency
+go get package/path@version
+
+# Or update go.mod
+go mod tidy
+
+# Or for local packages, check go.mod module path
+# Module: github.com/user/project
+# Import: github.com/user/project/internal/pkg
+```
+
+### 6. Missing Return
+
+**Error:** `missing return at end of function`
+
+**Fix:**
+```go
+func Process() (int, error) {
+    if condition {
+        return 0, errors.New("error")
+    }
+    return 42, nil  // Add missing return
+}
+```
+
+### 7. Unused Variable/Import
+
+**Error:** `x declared but not used` or `imported and not used`
+
+**Fix:**
+```go
+// Remove unused variable
+x := getValue()  // Remove if x not used
+
+// Use blank identifier if intentionally ignoring
+_ = getValue()
+
+// Remove unused import or use blank import for side effects
+import _ "package/for/init/only"
+```
+
+### 8. Multiple-Value in Single-Value Context
+
+**Error:** `multiple-value X() in single-value context`
+
+**Fix:**
+```go
+// Wrong
+result := funcReturningTwo()
+
+// Correct
+result, err := funcReturningTwo()
+if err != nil {
+    return err
+}
+
+// Or ignore second value
+result, _ := funcReturningTwo()
+```
+
+### 9. Cannot Assign to Field
+
+**Error:** `cannot assign to struct field x.y in map`
+
+**Fix:**
+```go
+// Cannot modify struct in map directly
+m := map[string]MyStruct{}
+m["key"].Field = "value"  // Error!
+
+// Fix: Use pointer map or copy-modify-reassign
+m := map[string]*MyStruct{}
+m["key"] = &MyStruct{}
+m["key"].Field = "value"  // Works
+
+// Or
+m := map[string]MyStruct{}
+tmp := m["key"]
+tmp.Field = "value"
+m["key"] = tmp
+```
+
+### 10. Invalid Operation (Type Assertion)
+
+**Error:** `invalid type assertion: x.(T) (non-interface type)`
+
+**Fix:**
+```go
+// Can only assert from interface
+var i interface{} = "hello"
+s := i.(string)  // Valid
+
+var s string = "hello"
+// s.(int)  // Invalid - s is not interface
+```
+
+## Module Issues
+
+### Replace Directive Problems
+
+```bash
+# Check for local replaces that might be invalid
+grep "replace" go.mod
+
+# Remove stale replaces
+go mod edit -dropreplace=package/path
+```
+
+### Version Conflicts
+
+```bash
+# See why a version is selected
+go mod why -m package
+
+# Get specific version
+go get package@v1.2.3
+
+# Update all dependencies
+go get -u ./...
+```
+
+### Checksum Mismatch
+
+```bash
+# Clear module cache
+go clean -modcache
+
+# Re-download
+go mod download
+```
+
+## Go Vet Issues
+
+### Suspicious Constructs
+
+```go
+// Vet: unreachable code
+func example() int {
+    return 1
+    fmt.Println("never runs")  // Remove this
+}
+
+// Vet: printf format mismatch
+fmt.Printf("%d", "string")  // Fix: %s
+
+// Vet: copying lock value
+var mu sync.Mutex
+mu2 := mu  // Fix: use pointer *sync.Mutex
+
+// Vet: self-assignment
+x = x  // Remove pointless assignment
+```
+
+## Fix Strategy
+
+1. **Read the full error message** - Go errors are descriptive
+2. **Identify the file and line number** - Go directly to the source
+3. **Understand the context** - Read surrounding code
+4. **Make minimal fix** - Don't refactor, just fix the error
+5. **Verify fix** - Run `go build ./...` again
+6. **Check for cascading errors** - One fix might reveal others
+
+## Resolution Workflow
+
+```
+1. go build ./...
+   ↓ Error?
+2. Parse error message
+   ↓
+3. Read affected file
+   ↓
+4. Apply minimal fix
+   ↓
+5. go build ./...
+   ↓ Still errors?
+   → Back to step 2
+   ↓ Success?
+6. go vet ./...
+   ↓ Warnings?
+   → Fix and repeat
+   ↓
+7. go test ./...
+   ↓
+8. Done!
+```
+
+## Stop Conditions
+
+Stop and report if:
+- Same error persists after 3 fix attempts
+- Fix introduces more errors than it resolves
+- Error requires architectural changes beyond scope
+- Circular dependency that needs package restructuring
+- Missing external dependency that needs manual installation
+
+## Output Format
+
+After each fix attempt:
+
+```
+[FIXED] internal/handler/user.go:42
+Error: undefined: UserService
+Fix: Added import "project/internal/service"
+
+Remaining errors: 3
+```
+
+Final summary:
+```
+Build Status: SUCCESS/FAILED
+Errors Fixed: N
+Vet Warnings Fixed: N
+Files Modified: list
+Remaining Issues: list (if any)
+```
+
+## Important Notes
+
+- **Never** add `//nolint` comments without explicit approval
+- **Never** change function signatures unless necessary for the fix
+- **Always** run `go mod tidy` after adding/removing imports
+- **Prefer** fixing root cause over suppressing symptoms
+- **Document** any non-obvious fixes with inline comments
+
+Build errors should be fixed surgically. The goal is a working build, not a refactored codebase.

agents/go-reviewer.md

@@ -0,0 +1,267 @@
+---
+name: go-reviewer
+description: Expert Go code reviewer specializing in idiomatic Go, concurrency patterns, error handling, and performance. Use for all Go code changes. MUST BE USED for Go projects.
+tools: ["Read", "Grep", "Glob", "Bash"]
+model: opus
+---
+
+You are a senior Go code reviewer ensuring high standards of idiomatic Go and best practices.
+
+When invoked:
+1. Run `git diff -- '*.go'` to see recent Go file changes
+2. Run `go vet ./...` and `staticcheck ./...` if available
+3. Focus on modified `.go` files
+4. Begin review immediately
+
+## Security Checks (CRITICAL)
+
+- **SQL Injection**: String concatenation in `database/sql` queries
+  ```go
+  // Bad
+  db.Query("SELECT * FROM users WHERE id = " + userID)
+  // Good
+  db.Query("SELECT * FROM users WHERE id = $1", userID)
+  ```
+
+- **Command Injection**: Unvalidated input in `os/exec`
+  ```go
+  // Bad
+  exec.Command("sh", "-c", "echo " + userInput)
+  // Good
+  exec.Command("echo", userInput)
+  ```
+
+- **Path Traversal**: User-controlled file paths
+  ```go
+  // Bad
+  os.ReadFile(filepath.Join(baseDir, userPath))
+  // Good
+  cleanPath := filepath.Clean(userPath)
+  if strings.HasPrefix(cleanPath, "..") {
+      return ErrInvalidPath
+  }
+  ```
+
+- **Race Conditions**: Shared state without synchronization
+- **Unsafe Package**: Use of `unsafe` without justification
+- **Hardcoded Secrets**: API keys, passwords in source
+- **Insecure TLS**: `InsecureSkipVerify: true`
+- **Weak Crypto**: Use of MD5/SHA1 for security purposes
+
+## Error Handling (CRITICAL)
+
+- **Ignored Errors**: Using `_` to ignore errors
+  ```go
+  // Bad
+  result, _ := doSomething()
+  // Good
+  result, err := doSomething()
+  if err != nil {
+      return fmt.Errorf("do something: %w", err)
+  }
+  ```
+
+- **Missing Error Wrapping**: Errors without context
+  ```go
+  // Bad
+  return err
+  // Good
+  return fmt.Errorf("load config %s: %w", path, err)
+  ```
+
+- **Panic Instead of Error**: Using panic for recoverable errors
+- **errors.Is/As**: Not using for error checking
+  ```go
+  // Bad
+  if err == sql.ErrNoRows
+  // Good
+  if errors.Is(err, sql.ErrNoRows)
+  ```
+
+## Concurrency (HIGH)
+
+- **Goroutine Leaks**: Goroutines that never terminate
+  ```go
+  // Bad: No way to stop goroutine
+  go func() {
+      for { doWork() }
+  }()
+  // Good: Context for cancellation
+  go func() {
+      for {
+          select {
+          case <-ctx.Done():
+              return
+          default:
+              doWork()
+          }
+      }
+  }()
+  ```
+
+- **Race Conditions**: Run `go build -race ./...`
+- **Unbuffered Channel Deadlock**: Sending without receiver
+- **Missing sync.WaitGroup**: Goroutines without coordination
+- **Context Not Propagated**: Ignoring context in nested calls
+- **Mutex Misuse**: Not using `defer mu.Unlock()`
+  ```go
+  // Bad: Unlock might not be called on panic
+  mu.Lock()
+  doSomething()
+  mu.Unlock()
+  // Good
+  mu.Lock()
+  defer mu.Unlock()
+  doSomething()
+  ```
+
+## Code Quality (HIGH)
+
+- **Large Functions**: Functions over 50 lines
+- **Deep Nesting**: More than 4 levels of indentation
+- **Interface Pollution**: Defining interfaces not used for abstraction
+- **Package-Level Variables**: Mutable global state
+- **Naked Returns**: In functions longer than a few lines
+  ```go
+  // Bad in long functions
+  func process() (result int, err error) {
+      // ... 30 lines ...
+      return // What's being returned?
+  }
+  ```
+
+- **Non-Idiomatic Code**:
+  ```go
+  // Bad
+  if err != nil {
+      return err
+  } else {
+      doSomething()
+  }
+  // Good: Early return
+  if err != nil {
+      return err
+  }
+  doSomething()
+  ```
+
+## Performance (MEDIUM)
+
+- **Inefficient String Building**:
+  ```go
+  // Bad
+  for _, s := range parts { result += s }
+  // Good
+  var sb strings.Builder
+  for _, s := range parts { sb.WriteString(s) }
+  ```
+
+- **Slice Pre-allocation**: Not using `make([]T, 0, cap)`
+- **Pointer vs Value Receivers**: Inconsistent usage
+- **Unnecessary Allocations**: Creating objects in hot paths
+- **N+1 Queries**: Database queries in loops
+- **Missing Connection Pooling**: Creating new DB connections per request
+
+## Best Practices (MEDIUM)
+
+- **Accept Interfaces, Return Structs**: Functions should accept interface parameters
+- **Context First**: Context should be first parameter
+  ```go
+  // Bad
+  func Process(id string, ctx context.Context)
+  // Good
+  func Process(ctx context.Context, id string)
+  ```
+
+- **Table-Driven Tests**: Tests should use table-driven pattern
+- **Godoc Comments**: Exported functions need documentation
+  ```go
+  // ProcessData transforms raw input into structured output.
+  // It returns an error if the input is malformed.
+  func ProcessData(input []byte) (*Data, error)
+  ```
+
+- **Error Messages**: Should be lowercase, no punctuation
+  ```go
+  // Bad
+  return errors.New("Failed to process data.")
+  // Good
+  return errors.New("failed to process data")
+  ```
+
+- **Package Naming**: Short, lowercase, no underscores
+
+## Go-Specific Anti-Patterns
+
+- **init() Abuse**: Complex logic in init functions
+- **Empty Interface Overuse**: Using `interface{}` instead of generics
+- **Type Assertions Without ok**: Can panic
+  ```go
+  // Bad
+  v := x.(string)
+  // Good
+  v, ok := x.(string)
+  if !ok { return ErrInvalidType }
+  ```
+
+- **Deferred Call in Loop**: Resource accumulation
+  ```go
+  // Bad: Files opened until function returns
+  for _, path := range paths {
+      f, _ := os.Open(path)
+      defer f.Close()
+  }
+  // Good: Close in loop iteration
+  for _, path := range paths {
+      func() {
+          f, _ := os.Open(path)
+          defer f.Close()
+          process(f)
+      }()
+  }
+  ```
+
+## Review Output Format
+
+For each issue:
+```
+[CRITICAL] SQL Injection vulnerability
+File: internal/repository/user.go:42
+Issue: User input directly concatenated into SQL query
+Fix: Use parameterized query
+
+query := "SELECT * FROM users WHERE id = " + userID  // Bad
+query := "SELECT * FROM users WHERE id = $1"         // Good
+db.Query(query, userID)
+```
+
+## Diagnostic Commands
+
+Run these checks:
+```bash
+# Static analysis
+go vet ./...
+staticcheck ./...
+golangci-lint run
+
+# Race detection
+go build -race ./...
+go test -race ./...
+
+# Security scanning
+govulncheck ./...
+```
+
+## Approval Criteria
+
+- **Approve**: No CRITICAL or HIGH issues
+- **Warning**: MEDIUM issues only (can merge with caution)
+- **Block**: CRITICAL or HIGH issues found
+
+## Go Version Considerations
+
+- Check `go.mod` for minimum Go version
+- Note if code uses features from newer Go versions (generics 1.18+, fuzzing 1.18+)
+- Flag deprecated functions from standard library
+
+Review with the mindset: "Would this code pass review at Google or a top Go shop?"

commands/go-build.md

@@ -0,0 +1,183 @@
+---
+description: Fix Go build errors, go vet warnings, and linter issues incrementally. Invokes the go-build-resolver agent for minimal, surgical fixes.
+---
+
+# Go Build and Fix
+
+This command invokes the **go-build-resolver** agent to incrementally fix Go build errors with minimal changes.
+
+## What This Command Does
+
+1. **Run Diagnostics**: Execute `go build`, `go vet`, `staticcheck`
+2. **Parse Errors**: Group by file and sort by severity
+3. **Fix Incrementally**: One error at a time
+4. **Verify Each Fix**: Re-run build after each change
+5. **Report Summary**: Show what was fixed and what remains
+
+## When to Use
+
+Use `/go-build` when:
+- `go build ./...` fails with errors
+- `go vet ./...` reports issues
+- `golangci-lint run` shows warnings
+- Module dependencies are broken
+- After pulling changes that break the build
+
+## Diagnostic Commands Run
+
+```bash
+# Primary build check
+go build ./...
+
+# Static analysis
+go vet ./...
+
+# Extended linting (if available)
+staticcheck ./...
+golangci-lint run
+
+# Module issues
+go mod verify
+go mod tidy -v
+```
+
+## Example Session
+
+```
+User: /go-build
+
+Agent:
+# Go Build Resolution
+
+## Initial Diagnostics
+
+```bash
+$ go build ./...
+internal/service/user.go:25:15: undefined: UserRepository
+internal/handler/api.go:42:9: cannot use x (type string) as type int
+internal/handler/api.go:58:2: missing return at end of function
+```
+
+Errors found: 3
+
+## Fix 1: Undefined Identifier
+
+File: internal/service/user.go:25
+Error: undefined: UserRepository
+Cause: Missing import
+
+```go
+// Added import
+import "project/internal/repository"
+
+// Changed
+var repo UserRepository
+// To
+var repo repository.UserRepository
+```
+
+```bash
+$ go build ./...
+# 2 errors remaining
+```
+
+## Fix 2: Type Mismatch
+
+File: internal/handler/api.go:42
+Error: cannot use x (type string) as type int
+
+```go
+// Changed
+count := params.Get("count")
+// To
+countStr := params.Get("count")
+count, _ := strconv.Atoi(countStr)
+```
+
+```bash
+$ go build ./...
+# 1 error remaining
+```
+
+## Fix 3: Missing Return
+
+File: internal/handler/api.go:58
+Error: missing return at end of function
+
+```go
+func GetUser(id string) (*User, error) {
+    if id == "" {
+        return nil, ErrInvalidID
+    }
+    user := findUser(id)
+    // Added missing return
+    return user, nil
+}
+```
+
+```bash
+$ go build ./...
+# Build successful!
+```
+
+## Final Verification
+
+```bash
+$ go vet ./...
+# No issues
+
+$ go test ./...
+ok      project/internal/service   0.015s
+ok      project/internal/handler   0.023s
+```
+
+## Summary
+
+| Metric | Count |
+|--------|-------|
+| Build errors fixed | 3 |
+| Vet warnings fixed | 0 |
+| Files modified | 2 |
+| Remaining issues | 0 |
+
+Build Status: ✅ SUCCESS
+```
+
+## Common Errors Fixed
+
+| Error | Typical Fix |
+|-------|-------------|
+| `undefined: X` | Add import or fix typo |
+| `cannot use X as Y` | Type conversion or fix assignment |
+| `missing return` | Add return statement |
+| `X does not implement Y` | Add missing method |
+| `import cycle` | Restructure packages |
+| `declared but not used` | Remove or use variable |
+| `cannot find package` | `go get` or `go mod tidy` |
+
+## Fix Strategy
+
+1. **Build errors first** - Code must compile
+2. **Vet warnings second** - Fix suspicious constructs
+3. **Lint warnings third** - Style and best practices
+4. **One fix at a time** - Verify each change
+5. **Minimal changes** - Don't refactor, just fix
+
+## Stop Conditions
+
+The agent will stop and report if:
+- Same error persists after 3 attempts
+- Fix introduces more errors
+- Requires architectural changes
+- Missing external dependencies
+
+## Related Commands
+
+- `/go-test` - Run tests after build succeeds
+- `/go-review` - Review code quality
+- `/verify` - Full verification loop
+
+## Related
+
+- Agent: `agents/go-build-resolver.md`
+- Skill: `skills/golang-patterns/`

commands/go-review.md

@@ -0,0 +1,148 @@
+---
+description: Comprehensive Go code review for idiomatic patterns, concurrency safety, error handling, and security. Invokes the go-reviewer agent.
+---
+
+# Go Code Review
+
+This command invokes the **go-reviewer** agent for comprehensive Go-specific code review.
+
+## What This Command Does
+
+1. **Identify Go Changes**: Find modified `.go` files via `git diff`
+2. **Run Static Analysis**: Execute `go vet`, `staticcheck`, and `golangci-lint`
+3. **Security Scan**: Check for SQL injection, command injection, race conditions
+4. **Concurrency Review**: Analyze goroutine safety, channel usage, mutex patterns
+5. **Idiomatic Go Check**: Verify code follows Go conventions and best practices
+6. **Generate Report**: Categorize issues by severity
+
+## When to Use
+
+Use `/go-review` when:
+- After writing or modifying Go code
+- Before committing Go changes
+- Reviewing pull requests with Go code
+- Onboarding to a new Go codebase
+- Learning idiomatic Go patterns
+
+## Review Categories
+
+### CRITICAL (Must Fix)
+- SQL/Command injection vulnerabilities
+- Race conditions without synchronization
+- Goroutine leaks
+- Hardcoded credentials
+- Unsafe pointer usage
+- Ignored errors in critical paths
+
+### HIGH (Should Fix)
+- Missing error wrapping with context
+- Panic instead of error returns
+- Context not propagated
+- Unbuffered channels causing deadlocks
+- Interface not satisfied errors
+- Missing mutex protection
+
+### MEDIUM (Consider)
+- Non-idiomatic code patterns
+- Missing godoc comments on exports
+- Inefficient string concatenation
+- Slice not preallocated
+- Table-driven tests not used
+
+## Automated Checks Run
+
+```bash
+# Static analysis
+go vet ./...
+
+# Advanced checks (if installed)
+staticcheck ./...
+golangci-lint run
+
+# Race detection
+go build -race ./...
+
+# Security vulnerabilities
+govulncheck ./...
+```
+
+## Example Usage
+
+```
+User: /go-review
+
+Agent:
+# Go Code Review Report
+
+## Files Reviewed
+- internal/handler/user.go (modified)
+- internal/service/auth.go (modified)
+
+## Static Analysis Results
+✓ go vet: No issues
+✓ staticcheck: No issues
+
+## Issues Found
+
+[CRITICAL] Race Condition
+File: internal/service/auth.go:45
+Issue: Shared map accessed without synchronization
+```go
+var cache = map[string]*Session{}  // Concurrent access!
+
+func GetSession(id string) *Session {
+    return cache[id]  // Race condition
+}
+```
+Fix: Use sync.RWMutex or sync.Map
+```go
+var (
+    cache   = map[string]*Session{}
+    cacheMu sync.RWMutex
+)
+
+func GetSession(id string) *Session {
+    cacheMu.RLock()
+    defer cacheMu.RUnlock()
+    return cache[id]
+}
+```
+
+[HIGH] Missing Error Context
+File: internal/handler/user.go:28
+Issue: Error returned without context
+```go
+return err  // No context
+```
+Fix: Wrap with context
+```go
+return fmt.Errorf("get user %s: %w", userID, err)
+```
+
+## Summary
+- CRITICAL: 1
+- HIGH: 1
+- MEDIUM: 0
+
+Recommendation: ❌ Block merge until CRITICAL issue is fixed
+```
+
+## Approval Criteria
+
+| Status | Condition |
+|--------|-----------|
+| ✅ Approve | No CRITICAL or HIGH issues |
+| ⚠️ Warning | Only MEDIUM issues (merge with caution) |
+| ❌ Block | CRITICAL or HIGH issues found |
+
+## Integration with Other Commands
+
+- Use `/go-test` first to ensure tests pass
+- Use `/go-build` if build errors occur
+- Use `/go-review` before committing
+- Use `/code-review` for non-Go specific concerns
+
+## Related
+
+- Agent: `agents/go-reviewer.md`
+- Skills: `skills/golang-patterns/`, `skills/golang-testing/`

commands/go-test.md

@@ -0,0 +1,268 @@
+---
+description: Enforce TDD workflow for Go. Write table-driven tests first, then implement. Verify 80%+ coverage with go test -cover.
+---
+
+# Go TDD Command
+
+This command enforces test-driven development methodology for Go code using idiomatic Go testing patterns.
+
+## What This Command Does
+
+1. **Define Types/Interfaces**: Scaffold function signatures first
+2. **Write Table-Driven Tests**: Create comprehensive test cases (RED)
+3. **Run Tests**: Verify tests fail for the right reason
+4. **Implement Code**: Write minimal code to pass (GREEN)
+5. **Refactor**: Improve while keeping tests green
+6. **Check Coverage**: Ensure 80%+ coverage
+
+## When to Use
+
+Use `/go-test` when:
+- Implementing new Go functions
+- Adding test coverage to existing code
+- Fixing bugs (write failing test first)
+- Building critical business logic
+- Learning TDD workflow in Go
+
+## TDD Cycle
+
+```
+RED     → Write failing table-driven test
+GREEN   → Implement minimal code to pass
+REFACTOR → Improve code, tests stay green
+REPEAT  → Next test case
+```
+
+## Example Session
+
+```
+User: /go-test I need a function to validate email addresses
+
+Agent:
+# TDD Session: Email Validator
+
+## Step 1: Define Interface
+
+```go
+// validator/email.go
+package validator
+
+// ValidateEmail checks if the given string is a valid email address.
+// Returns nil if valid, error describing the issue otherwise.
+func ValidateEmail(email string) error {
+    panic("not implemented")
+}
+```
+
+## Step 2: Write Table-Driven Tests (RED)
+
+```go
+// validator/email_test.go
+package validator
+
+import (
+    "testing"
+)
+
+func TestValidateEmail(t *testing.T) {
+    tests := []struct {
+        name    string
+        email   string
+        wantErr bool
+    }{
+        // Valid emails
+        {"simple email", "user@example.com", false},
+        {"with subdomain", "user@mail.example.com", false},
+        {"with plus", "user+tag@example.com", false},
+        {"with dots", "first.last@example.com", false},
+
+        // Invalid emails
+        {"empty string", "", true},
+        {"no at sign", "userexample.com", true},
+        {"no domain", "user@", true},
+        {"no local part", "@example.com", true},
+        {"double at", "user@@example.com", true},
+        {"spaces", "user @example.com", true},
+        {"no tld", "user@example", true},
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            err := ValidateEmail(tt.email)
+            if tt.wantErr && err == nil {
+                t.Errorf("ValidateEmail(%q) = nil; want error", tt.email)
+            }
+            if !tt.wantErr && err != nil {
+                t.Errorf("ValidateEmail(%q) = %v; want nil", tt.email, err)
+            }
+        })
+    }
+}
+```
+
+## Step 3: Run Tests - Verify FAIL
+
+```bash
+$ go test ./validator/...
+
+--- FAIL: TestValidateEmail (0.00s)
+    --- FAIL: TestValidateEmail/simple_email (0.00s)
+        panic: not implemented
+
+FAIL
+```
+
+✓ Tests fail as expected (panic).
+
+## Step 4: Implement Minimal Code (GREEN)
+
+```go
+// validator/email.go
+package validator
+
+import (
+    "errors"
+    "regexp"
+)
+
+var emailRegex = regexp.MustCompile(`^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$`)
+
+var (
+    ErrEmailEmpty   = errors.New("email cannot be empty")
+    ErrEmailInvalid = errors.New("email format is invalid")
+)
+
+func ValidateEmail(email string) error {
+    if email == "" {
+        return ErrEmailEmpty
+    }
+    if !emailRegex.MatchString(email) {
+        return ErrEmailInvalid
+    }
+    return nil
+}
+```
+
+## Step 5: Run Tests - Verify PASS
+
+```bash
+$ go test ./validator/...
+
+PASS
+ok      project/validator    0.003s
+```
+
+✓ All tests passing!
+
+## Step 6: Check Coverage
+
+```bash
+$ go test -cover ./validator/...
+
+PASS
+coverage: 100.0% of statements
+ok      project/validator    0.003s
+```
+
+✓ Coverage: 100%
+
+## TDD Complete!
+```
+
+## Test Patterns
+
+### Table-Driven Tests
+```go
+tests := []struct {
+    name     string
+    input    InputType
+    want     OutputType
+    wantErr  bool
+}{
+    {"case 1", input1, want1, false},
+    {"case 2", input2, want2, true},
+}
+
+for _, tt := range tests {
+    t.Run(tt.name, func(t *testing.T) {
+        got, err := Function(tt.input)
+        // assertions
+    })
+}
+```
+
+### Parallel Tests
+```go
+for _, tt := range tests {
+    tt := tt // Capture
+    t.Run(tt.name, func(t *testing.T) {
+        t.Parallel()
+        // test body
+    })
+}
+```
+
+### Test Helpers
+```go
+func setupTestDB(t *testing.T) *sql.DB {
+    t.Helper()
+    db := createDB()
+    t.Cleanup(func() { db.Close() })
+    return db
+}
+```
+
+## Coverage Commands
+
+```bash
+# Basic coverage
+go test -cover ./...
+
+# Coverage profile
+go test -coverprofile=coverage.out ./...
+
+# View in browser
+go tool cover -html=coverage.out
+
+# Coverage by function
+go tool cover -func=coverage.out
+
+# With race detection
+go test -race -cover ./...
+```
+
+## Coverage Targets
+
+| Code Type | Target |
+|-----------|--------|
+| Critical business logic | 100% |
+| Public APIs | 90%+ |
+| General code | 80%+ |
+| Generated code | Exclude |
+
+## TDD Best Practices
+
+**DO:**
+- Write test FIRST, before any implementation
+- Run tests after each change
+- Use table-driven tests for comprehensive coverage
+- Test behavior, not implementation details
+- Include edge cases (empty, nil, max values)
+
+**DON'T:**
+- Write implementation before tests
+- Skip the RED phase
+- Test private functions directly
+- Use `time.Sleep` in tests
+- Ignore flaky tests
+
+## Related Commands
+
+- `/go-build` - Fix build errors
+- `/go-review` - Review code after implementation
+- `/verify` - Run full verification loop
+
+## Related
+
+- Skill: `skills/golang-testing/`
+- Skill: `skills/tdd-workflow/`

skills/golang-patterns/SKILL.md

@@ -0,0 +1,673 @@
+---
+name: golang-patterns
+description: Idiomatic Go patterns, best practices, and conventions for building robust, efficient, and maintainable Go applications.
+---
+
+# Go Development Patterns
+
+Idiomatic Go patterns and best practices for building robust, efficient, and maintainable applications.
+
+## When to Activate
+
+- Writing new Go code
+- Reviewing Go code
+- Refactoring existing Go code
+- Designing Go packages/modules
+
+## Core Principles
+
+### 1. Simplicity and Clarity
+
+Go favors simplicity over cleverness. Code should be obvious and easy to read.
+
+```go
+// Good: Clear and direct
+func GetUser(id string) (*User, error) {
+    user, err := db.FindUser(id)
+    if err != nil {
+        return nil, fmt.Errorf("get user %s: %w", id, err)
+    }
+    return user, nil
+}
+
+// Bad: Overly clever
+func GetUser(id string) (*User, error) {
+    return func() (*User, error) {
+        if u, e := db.FindUser(id); e == nil {
+            return u, nil
+        } else {
+            return nil, e
+        }
+    }()
+}
+```
+
+### 2. Make the Zero Value Useful
+
+Design types so their zero value is immediately usable without initialization.
+
+```go
+// Good: Zero value is useful
+type Counter struct {
+    mu    sync.Mutex
+    count int // zero value is 0, ready to use
+}
+
+func (c *Counter) Inc() {
+    c.mu.Lock()
+    c.count++
+    c.mu.Unlock()
+}
+
+// Good: bytes.Buffer works with zero value
+var buf bytes.Buffer
+buf.WriteString("hello")
+
+// Bad: Requires initialization
+type BadCounter struct {
+    counts map[string]int // nil map will panic
+}
+```
+
+### 3. Accept Interfaces, Return Structs
+
+Functions should accept interface parameters and return concrete types.
+
+```go
+// Good: Accepts interface, returns concrete type
+func ProcessData(r io.Reader) (*Result, error) {
+    data, err := io.ReadAll(r)
+    if err != nil {
+        return nil, err
+    }
+    return &Result{Data: data}, nil
+}
+
+// Bad: Returns interface (hides implementation details unnecessarily)
+func ProcessData(r io.Reader) (io.Reader, error) {
+    // ...
+}
+```
+
+## Error Handling Patterns
+
+### Error Wrapping with Context
+
+```go
+// Good: Wrap errors with context
+func LoadConfig(path string) (*Config, error) {
+    data, err := os.ReadFile(path)
+    if err != nil {
+        return nil, fmt.Errorf("load config %s: %w", path, err)
+    }
+
+    var cfg Config
+    if err := json.Unmarshal(data, &cfg); err != nil {
+        return nil, fmt.Errorf("parse config %s: %w", path, err)
+    }
+
+    return &cfg, nil
+}
+```
+
+### Custom Error Types
+
+```go
+// Define domain-specific errors
+type ValidationError struct {
+    Field   string
+    Message string
+}
+
+func (e *ValidationError) Error() string {
+    return fmt.Sprintf("validation failed on %s: %s", e.Field, e.Message)
+}
+
+// Sentinel errors for common cases
+var (
+    ErrNotFound     = errors.New("resource not found")
+    ErrUnauthorized = errors.New("unauthorized")
+    ErrInvalidInput = errors.New("invalid input")
+)
+```
+
+### Error Checking with errors.Is and errors.As
+
+```go
+func HandleError(err error) {
+    // Check for specific error
+    if errors.Is(err, sql.ErrNoRows) {
+        log.Println("No records found")
+        return
+    }
+
+    // Check for error type
+    var validationErr *ValidationError
+    if errors.As(err, &validationErr) {
+        log.Printf("Validation error on field %s: %s",
+            validationErr.Field, validationErr.Message)
+        return
+    }
+
+    // Unknown error
+    log.Printf("Unexpected error: %v", err)
+}
+```
+
+### Never Ignore Errors
+
+```go
+// Bad: Ignoring error with blank identifier
+result, _ := doSomething()
+
+// Good: Handle or explicitly document why it's safe to ignore
+result, err := doSomething()
+if err != nil {
+    return err
+}
+
+// Acceptable: When error truly doesn't matter (rare)
+_ = writer.Close() // Best-effort cleanup, error logged elsewhere
+```
+
+## Concurrency Patterns
+
+### Worker Pool
+
+```go
+func WorkerPool(jobs <-chan Job, results chan<- Result, numWorkers int) {
+    var wg sync.WaitGroup
+
+    for i := 0; i < numWorkers; i++ {
+        wg.Add(1)
+        go func() {
+            defer wg.Done()
+            for job := range jobs {
+                results <- process(job)
+            }
+        }()
+    }
+
+    wg.Wait()
+    close(results)
+}
+```
+
+### Context for Cancellation and Timeouts
+
+```go
+func FetchWithTimeout(ctx context.Context, url string) ([]byte, error) {
+    ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+    defer cancel()
+
+    req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+    if err != nil {
+        return nil, fmt.Errorf("create request: %w", err)
+    }
+
+    resp, err := http.DefaultClient.Do(req)
+    if err != nil {
+        return nil, fmt.Errorf("fetch %s: %w", url, err)
+    }
+    defer resp.Body.Close()
+
+    return io.ReadAll(resp.Body)
+}
+```
+
+### Graceful Shutdown
+
+```go
+func GracefulShutdown(server *http.Server) {
+    quit := make(chan os.Signal, 1)
+    signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
+
+    <-quit
+    log.Println("Shutting down server...")
+
+    ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+    defer cancel()
+
+    if err := server.Shutdown(ctx); err != nil {
+        log.Fatalf("Server forced to shutdown: %v", err)
+    }
+
+    log.Println("Server exited")
+}
+```
+
+### errgroup for Coordinated Goroutines
+
+```go
+import "golang.org/x/sync/errgroup"
+
+func FetchAll(ctx context.Context, urls []string) ([][]byte, error) {
+    g, ctx := errgroup.WithContext(ctx)
+    results := make([][]byte, len(urls))
+
+    for i, url := range urls {
+        i, url := i, url // Capture loop variables
+        g.Go(func() error {
+            data, err := FetchWithTimeout(ctx, url)
+            if err != nil {
+                return err
+            }
+            results[i] = data
+            return nil
+        })
+    }
+
+    if err := g.Wait(); err != nil {
+        return nil, err
+    }
+    return results, nil
+}
+```
+
+### Avoiding Goroutine Leaks
+
+```go
+// Bad: Goroutine leak if context is cancelled
+func leakyFetch(ctx context.Context, url string) <-chan []byte {
+    ch := make(chan []byte)
+    go func() {
+        data, _ := fetch(url)
+        ch <- data // Blocks forever if no receiver
+    }()
+    return ch
+}
+
+// Good: Properly handles cancellation
+func safeFetch(ctx context.Context, url string) <-chan []byte {
+    ch := make(chan []byte, 1) // Buffered channel
+    go func() {
+        data, err := fetch(url)
+        if err != nil {
+            return
+        }
+        select {
+        case ch <- data:
+        case <-ctx.Done():
+        }
+    }()
+    return ch
+}
+```
+
+## Interface Design
+
+### Small, Focused Interfaces
+
+```go
+// Good: Single-method interfaces
+type Reader interface {
+    Read(p []byte) (n int, err error)
+}
+
+type Writer interface {
+    Write(p []byte) (n int, err error)
+}
+
+type Closer interface {
+    Close() error
+}
+
+// Compose interfaces as needed
+type ReadWriteCloser interface {
+    Reader
+    Writer
+    Closer
+}
+```
+
+### Define Interfaces Where They're Used
+
+```go
+// In the consumer package, not the provider
+package service
+
+// UserStore defines what this service needs
+type UserStore interface {
+    GetUser(id string) (*User, error)
+    SaveUser(user *User) error
+}
+
+type Service struct {
+    store UserStore
+}
+
+// Concrete implementation can be in another package
+// It doesn't need to know about this interface
+```
+
+### Optional Behavior with Type Assertions
+
+```go
+type Flusher interface {
+    Flush() error
+}
+
+func WriteAndFlush(w io.Writer, data []byte) error {
+    if _, err := w.Write(data); err != nil {
+        return err
+    }
+
+    // Flush if supported
+    if f, ok := w.(Flusher); ok {
+        return f.Flush()
+    }
+    return nil
+}
+```
+
+## Package Organization
+
+### Standard Project Layout
+
+```
+myproject/
+├── cmd/
+│   └── myapp/
+│       └── main.go           # Entry point
+├── internal/
+│   ├── handler/              # HTTP handlers
+│   ├── service/              # Business logic
+│   ├── repository/           # Data access
+│   └── config/               # Configuration
+├── pkg/
+│   └── client/               # Public API client
+├── api/
+│   └── v1/                   # API definitions (proto, OpenAPI)
+├── testdata/                 # Test fixtures
+├── go.mod
+├── go.sum
+└── Makefile
+```
+
+### Package Naming
+
+```go
+// Good: Short, lowercase, no underscores
+package http
+package json
+package user
+
+// Bad: Verbose, mixed case, or redundant
+package httpHandler
+package json_parser
+package userService // Redundant 'Service' suffix
+```
+
+### Avoid Package-Level State
+
+```go
+// Bad: Global mutable state
+var db *sql.DB
+
+func init() {
+    db, _ = sql.Open("postgres", os.Getenv("DATABASE_URL"))
+}
+
+// Good: Dependency injection
+type Server struct {
+    db *sql.DB
+}
+
+func NewServer(db *sql.DB) *Server {
+    return &Server{db: db}
+}
+```
+
+## Struct Design
+
+### Functional Options Pattern
+
+```go
+type Server struct {
+    addr    string
+    timeout time.Duration
+    logger  *log.Logger
+}
+
+type Option func(*Server)
+
+func WithTimeout(d time.Duration) Option {
+    return func(s *Server) {
+        s.timeout = d
+    }
+}
+
+func WithLogger(l *log.Logger) Option {
+    return func(s *Server) {
+        s.logger = l
+    }
+}
+
+func NewServer(addr string, opts ...Option) *Server {
+    s := &Server{
+        addr:    addr,
+        timeout: 30 * time.Second, // default
+        logger:  log.Default(),    // default
+    }
+    for _, opt := range opts {
+        opt(s)
+    }
+    return s
+}
+
+// Usage
+server := NewServer(":8080",
+    WithTimeout(60*time.Second),
+    WithLogger(customLogger),
+)
+```
+
+### Embedding for Composition
+
+```go
+type Logger struct {
+    prefix string
+}
+
+func (l *Logger) Log(msg string) {
+    fmt.Printf("[%s] %s\n", l.prefix, msg)
+}
+
+type Server struct {
+    *Logger // Embedding - Server gets Log method
+    addr    string
+}
+
+func NewServer(addr string) *Server {
+    return &Server{
+        Logger: &Logger{prefix: "SERVER"},
+        addr:   addr,
+    }
+}
+
+// Usage
+s := NewServer(":8080")
+s.Log("Starting...") // Calls embedded Logger.Log
+```
+
+## Memory and Performance
+
+### Preallocate Slices When Size is Known
+
+```go
+// Bad: Grows slice multiple times
+func processItems(items []Item) []Result {
+    var results []Result
+    for _, item := range items {
+        results = append(results, process(item))
+    }
+    return results
+}
+
+// Good: Single allocation
+func processItems(items []Item) []Result {
+    results := make([]Result, 0, len(items))
+    for _, item := range items {
+        results = append(results, process(item))
+    }
+    return results
+}
+```
+
+### Use sync.Pool for Frequent Allocations
+
+```go
+var bufferPool = sync.Pool{
+    New: func() interface{} {
+        return new(bytes.Buffer)
+    },
+}
+
+func ProcessRequest(data []byte) []byte {
+    buf := bufferPool.Get().(*bytes.Buffer)
+    defer func() {
+        buf.Reset()
+        bufferPool.Put(buf)
+    }()
+
+    buf.Write(data)
+    // Process...
+    return buf.Bytes()
+}
+```
+
+### Avoid String Concatenation in Loops
+
+```go
+// Bad: Creates many string allocations
+func join(parts []string) string {
+    var result string
+    for _, p := range parts {
+        result += p + ","
+    }
+    return result
+}
+
+// Good: Single allocation with strings.Builder
+func join(parts []string) string {
+    var sb strings.Builder
+    for i, p := range parts {
+        if i > 0 {
+            sb.WriteString(",")
+        }
+        sb.WriteString(p)
+    }
+    return sb.String()
+}
+
+// Best: Use standard library
+func join(parts []string) string {
+    return strings.Join(parts, ",")
+}
+```
+
+## Go Tooling Integration
+
+### Essential Commands
+
+```bash
+# Build and run
+go build ./...
+go run ./cmd/myapp
+
+# Testing
+go test ./...
+go test -race ./...
+go test -cover ./...
+
+# Static analysis
+go vet ./...
+staticcheck ./...
+golangci-lint run
+
+# Module management
+go mod tidy
+go mod verify
+
+# Formatting
+gofmt -w .
+goimports -w .
+```
+
+### Recommended Linter Configuration (.golangci.yml)
+
+```yaml
+linters:
+  enable:
+    - errcheck
+    - gosimple
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - gofmt
+    - goimports
+    - misspell
+    - unconvert
+    - unparam
+
+linters-settings:
+  errcheck:
+    check-type-assertions: true
+  govet:
+    check-shadowing: true
+
+issues:
+  exclude-use-default: false
+```
+
+## Quick Reference: Go Idioms
+
+| Idiom | Description |
+|-------|-------------|
+| Accept interfaces, return structs | Functions accept interface params, return concrete types |
+| Errors are values | Treat errors as first-class values, not exceptions |
+| Don't communicate by sharing memory | Use channels for coordination between goroutines |
+| Make the zero value useful | Types should work without explicit initialization |
+| A little copying is better than a little dependency | Avoid unnecessary external dependencies |
+| Clear is better than clever | Prioritize readability over cleverness |
+| gofmt is no one's favorite but everyone's friend | Always format with gofmt/goimports |
+| Return early | Handle errors first, keep happy path unindented |
+
+## Anti-Patterns to Avoid
+
+```go
+// Bad: Naked returns in long functions
+func process() (result int, err error) {
+    // ... 50 lines ...
+    return // What is being returned?
+}
+
+// Bad: Using panic for control flow
+func GetUser(id string) *User {
+    user, err := db.Find(id)
+    if err != nil {
+        panic(err) // Don't do this
+    }
+    return user
+}
+
+// Bad: Passing context in struct
+type Request struct {
+    ctx context.Context // Context should be first param
+    ID  string
+}
+
+// Good: Context as first parameter
+func ProcessRequest(ctx context.Context, id string) error {
+    // ...
+}
+
+// Bad: Mixing value and pointer receivers
+type Counter struct{ n int }
+func (c Counter) Value() int { return c.n }    // Value receiver
+func (c *Counter) Increment() { c.n++ }        // Pointer receiver
+// Pick one style and be consistent
+```
+
+**Remember**: Go code should be boring in the best way - predictable, consistent, and easy to understand. When in doubt, keep it simple.

skills/golang-testing/SKILL.md

@@ -0,0 +1,719 @@
+---
+name: golang-testing
+description: Go testing patterns including table-driven tests, subtests, benchmarks, fuzzing, and test coverage. Follows TDD methodology with idiomatic Go practices.
+---
+
+# Go Testing Patterns
+
+Comprehensive Go testing patterns for writing reliable, maintainable tests following TDD methodology.
+
+## When to Activate
+
+- Writing new Go functions or methods
+- Adding test coverage to existing code
+- Creating benchmarks for performance-critical code
+- Implementing fuzz tests for input validation
+- Following TDD workflow in Go projects
+
+## TDD Workflow for Go
+
+### The RED-GREEN-REFACTOR Cycle
+
+```
+RED     → Write a failing test first
+GREEN   → Write minimal code to pass the test
+REFACTOR → Improve code while keeping tests green
+REPEAT  → Continue with next requirement
+```
+
+### Step-by-Step TDD in Go
+
+```go
+// Step 1: Define the interface/signature
+// calculator.go
+package calculator
+
+func Add(a, b int) int {
+    panic("not implemented") // Placeholder
+}
+
+// Step 2: Write failing test (RED)
+// calculator_test.go
+package calculator
+
+import "testing"
+
+func TestAdd(t *testing.T) {
+    got := Add(2, 3)
+    want := 5
+    if got != want {
+        t.Errorf("Add(2, 3) = %d; want %d", got, want)
+    }
+}
+
+// Step 3: Run test - verify FAIL
+// $ go test
+// --- FAIL: TestAdd (0.00s)
+// panic: not implemented
+
+// Step 4: Implement minimal code (GREEN)
+func Add(a, b int) int {
+    return a + b
+}
+
+// Step 5: Run test - verify PASS
+// $ go test
+// PASS
+
+// Step 6: Refactor if needed, verify tests still pass
+```
+
+## Table-Driven Tests
+
+The standard pattern for Go tests. Enables comprehensive coverage with minimal code.
+
+```go
+func TestAdd(t *testing.T) {
+    tests := []struct {
+        name     string
+        a, b     int
+        expected int
+    }{
+        {"positive numbers", 2, 3, 5},
+        {"negative numbers", -1, -2, -3},
+        {"zero values", 0, 0, 0},
+        {"mixed signs", -1, 1, 0},
+        {"large numbers", 1000000, 2000000, 3000000},
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            got := Add(tt.a, tt.b)
+            if got != tt.expected {
+                t.Errorf("Add(%d, %d) = %d; want %d",
+                    tt.a, tt.b, got, tt.expected)
+            }
+        })
+    }
+}
+```
+
+### Table-Driven Tests with Error Cases
+
+```go
+func TestParseConfig(t *testing.T) {
+    tests := []struct {
+        name    string
+        input   string
+        want    *Config
+        wantErr bool
+    }{
+        {
+            name:  "valid config",
+            input: `{"host": "localhost", "port": 8080}`,
+            want:  &Config{Host: "localhost", Port: 8080},
+        },
+        {
+            name:    "invalid JSON",
+            input:   `{invalid}`,
+            wantErr: true,
+        },
+        {
+            name:    "empty input",
+            input:   "",
+            wantErr: true,
+        },
+        {
+            name:  "minimal config",
+            input: `{}`,
+            want:  &Config{}, // Zero value config
+        },
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            got, err := ParseConfig(tt.input)
+
+            if tt.wantErr {
+                if err == nil {
+                    t.Error("expected error, got nil")
+                }
+                return
+            }
+
+            if err != nil {
+                t.Fatalf("unexpected error: %v", err)
+            }
+
+            if !reflect.DeepEqual(got, tt.want) {
+                t.Errorf("got %+v; want %+v", got, tt.want)
+            }
+        })
+    }
+}
+```
+
+## Subtests and Sub-benchmarks
+
+### Organizing Related Tests
+
+```go
+func TestUser(t *testing.T) {
+    // Setup shared by all subtests
+    db := setupTestDB(t)
+
+    t.Run("Create", func(t *testing.T) {
+        user := &User{Name: "Alice"}
+        err := db.CreateUser(user)
+        if err != nil {
+            t.Fatalf("CreateUser failed: %v", err)
+        }
+        if user.ID == "" {
+            t.Error("expected user ID to be set")
+        }
+    })
+
+    t.Run("Get", func(t *testing.T) {
+        user, err := db.GetUser("alice-id")
+        if err != nil {
+            t.Fatalf("GetUser failed: %v", err)
+        }
+        if user.Name != "Alice" {
+            t.Errorf("got name %q; want %q", user.Name, "Alice")
+        }
+    })
+
+    t.Run("Update", func(t *testing.T) {
+        // ...
+    })
+
+    t.Run("Delete", func(t *testing.T) {
+        // ...
+    })
+}
+```
+
+### Parallel Subtests
+
+```go
+func TestParallel(t *testing.T) {
+    tests := []struct {
+        name  string
+        input string
+    }{
+        {"case1", "input1"},
+        {"case2", "input2"},
+        {"case3", "input3"},
+    }
+
+    for _, tt := range tests {
+        tt := tt // Capture range variable
+        t.Run(tt.name, func(t *testing.T) {
+            t.Parallel() // Run subtests in parallel
+            result := Process(tt.input)
+            // assertions...
+            _ = result
+        })
+    }
+}
+```
+
+## Test Helpers
+
+### Helper Functions
+
+```go
+func setupTestDB(t *testing.T) *sql.DB {
+    t.Helper() // Marks this as a helper function
+
+    db, err := sql.Open("sqlite3", ":memory:")
+    if err != nil {
+        t.Fatalf("failed to open database: %v", err)
+    }
+
+    // Cleanup when test finishes
+    t.Cleanup(func() {
+        db.Close()
+    })
+
+    // Run migrations
+    if _, err := db.Exec(schema); err != nil {
+        t.Fatalf("failed to create schema: %v", err)
+    }
+
+    return db
+}
+
+func assertNoError(t *testing.T, err error) {
+    t.Helper()
+    if err != nil {
+        t.Fatalf("unexpected error: %v", err)
+    }
+}
+
+func assertEqual[T comparable](t *testing.T, got, want T) {
+    t.Helper()
+    if got != want {
+        t.Errorf("got %v; want %v", got, want)
+    }
+}
+```
+
+### Temporary Files and Directories
+
+```go
+func TestFileProcessing(t *testing.T) {
+    // Create temp directory - automatically cleaned up
+    tmpDir := t.TempDir()
+
+    // Create test file
+    testFile := filepath.Join(tmpDir, "test.txt")
+    err := os.WriteFile(testFile, []byte("test content"), 0644)
+    if err != nil {
+        t.Fatalf("failed to create test file: %v", err)
+    }
+
+    // Run test
+    result, err := ProcessFile(testFile)
+    if err != nil {
+        t.Fatalf("ProcessFile failed: %v", err)
+    }
+
+    // Assert...
+    _ = result
+}
+```
+
+## Golden Files
+
+Testing against expected output files stored in `testdata/`.
+
+```go
+var update = flag.Bool("update", false, "update golden files")
+
+func TestRender(t *testing.T) {
+    tests := []struct {
+        name  string
+        input Template
+    }{
+        {"simple", Template{Name: "test"}},
+        {"complex", Template{Name: "test", Items: []string{"a", "b"}}},
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            got := Render(tt.input)
+
+            golden := filepath.Join("testdata", tt.name+".golden")
+
+            if *update {
+                // Update golden file: go test -update
+                err := os.WriteFile(golden, got, 0644)
+                if err != nil {
+                    t.Fatalf("failed to update golden file: %v", err)
+                }
+            }
+
+            want, err := os.ReadFile(golden)
+            if err != nil {
+                t.Fatalf("failed to read golden file: %v", err)
+            }
+
+            if !bytes.Equal(got, want) {
+                t.Errorf("output mismatch:\ngot:\n%s\nwant:\n%s", got, want)
+            }
+        })
+    }
+}
+```
+
+## Mocking with Interfaces
+
+### Interface-Based Mocking
+
+```go
+// Define interface for dependencies
+type UserRepository interface {
+    GetUser(id string) (*User, error)
+    SaveUser(user *User) error
+}
+
+// Production implementation
+type PostgresUserRepository struct {
+    db *sql.DB
+}
+
+func (r *PostgresUserRepository) GetUser(id string) (*User, error) {
+    // Real database query
+}
+
+// Mock implementation for tests
+type MockUserRepository struct {
+    GetUserFunc  func(id string) (*User, error)
+    SaveUserFunc func(user *User) error
+}
+
+func (m *MockUserRepository) GetUser(id string) (*User, error) {
+    return m.GetUserFunc(id)
+}
+
+func (m *MockUserRepository) SaveUser(user *User) error {
+    return m.SaveUserFunc(user)
+}
+
+// Test using mock
+func TestUserService(t *testing.T) {
+    mock := &MockUserRepository{
+        GetUserFunc: func(id string) (*User, error) {
+            if id == "123" {
+                return &User{ID: "123", Name: "Alice"}, nil
+            }
+            return nil, ErrNotFound
+        },
+    }
+
+    service := NewUserService(mock)
+
+    user, err := service.GetUserProfile("123")
+    if err != nil {
+        t.Fatalf("unexpected error: %v", err)
+    }
+    if user.Name != "Alice" {
+        t.Errorf("got name %q; want %q", user.Name, "Alice")
+    }
+}
+```
+
+## Benchmarks
+
+### Basic Benchmarks
+
+```go
+func BenchmarkProcess(b *testing.B) {
+    data := generateTestData(1000)
+    b.ResetTimer() // Don't count setup time
+
+    for i := 0; i < b.N; i++ {
+        Process(data)
+    }
+}
+
+// Run: go test -bench=BenchmarkProcess -benchmem
+// Output: BenchmarkProcess-8   10000   105234 ns/op   4096 B/op   10 allocs/op
+```
+
+### Benchmark with Different Sizes
+
+```go
+func BenchmarkSort(b *testing.B) {
+    sizes := []int{100, 1000, 10000, 100000}
+
+    for _, size := range sizes {
+        b.Run(fmt.Sprintf("size=%d", size), func(b *testing.B) {
+            data := generateRandomSlice(size)
+            b.ResetTimer()
+
+            for i := 0; i < b.N; i++ {
+                // Make a copy to avoid sorting already sorted data
+                tmp := make([]int, len(data))
+                copy(tmp, data)
+                sort.Ints(tmp)
+            }
+        })
+    }
+}
+```
+
+### Memory Allocation Benchmarks
+
+```go
+func BenchmarkStringConcat(b *testing.B) {
+    parts := []string{"hello", "world", "foo", "bar", "baz"}
+
+    b.Run("plus", func(b *testing.B) {
+        for i := 0; i < b.N; i++ {
+            var s string
+            for _, p := range parts {
+                s += p
+            }
+            _ = s
+        }
+    })
+
+    b.Run("builder", func(b *testing.B) {
+        for i := 0; i < b.N; i++ {
+            var sb strings.Builder
+            for _, p := range parts {
+                sb.WriteString(p)
+            }
+            _ = sb.String()
+        }
+    })
+
+    b.Run("join", func(b *testing.B) {
+        for i := 0; i < b.N; i++ {
+            _ = strings.Join(parts, "")
+        }
+    })
+}
+```
+
+## Fuzzing (Go 1.18+)
+
+### Basic Fuzz Test
+
+```go
+func FuzzParseJSON(f *testing.F) {
+    // Add seed corpus
+    f.Add(`{"name": "test"}`)
+    f.Add(`{"count": 123}`)
+    f.Add(`[]`)
+    f.Add(`""`)
+
+    f.Fuzz(func(t *testing.T, input string) {
+        var result map[string]interface{}
+        err := json.Unmarshal([]byte(input), &result)
+
+        if err != nil {
+            // Invalid JSON is expected for random input
+            return
+        }
+
+        // If parsing succeeded, re-encoding should work
+        _, err = json.Marshal(result)
+        if err != nil {
+            t.Errorf("Marshal failed after successful Unmarshal: %v", err)
+        }
+    })
+}
+
+// Run: go test -fuzz=FuzzParseJSON -fuzztime=30s
+```
+
+### Fuzz Test with Multiple Inputs
+
+```go
+func FuzzCompare(f *testing.F) {
+    f.Add("hello", "world")
+    f.Add("", "")
+    f.Add("abc", "abc")
+
+    f.Fuzz(func(t *testing.T, a, b string) {
+        result := Compare(a, b)
+
+        // Property: Compare(a, a) should always equal 0
+        if a == b && result != 0 {
+            t.Errorf("Compare(%q, %q) = %d; want 0", a, b, result)
+        }
+
+        // Property: Compare(a, b) and Compare(b, a) should have opposite signs
+        reverse := Compare(b, a)
+        if (result > 0 && reverse >= 0) || (result < 0 && reverse <= 0) {
+            if result != 0 || reverse != 0 {
+                t.Errorf("Compare(%q, %q) = %d, Compare(%q, %q) = %d; inconsistent",
+                    a, b, result, b, a, reverse)
+            }
+        }
+    })
+}
+```
+
+## Test Coverage
+
+### Running Coverage
+
+```bash
+# Basic coverage
+go test -cover ./...
+
+# Generate coverage profile
+go test -coverprofile=coverage.out ./...
+
+# View coverage in browser
+go tool cover -html=coverage.out
+
+# View coverage by function
+go tool cover -func=coverage.out
+
+# Coverage with race detection
+go test -race -coverprofile=coverage.out ./...
+```
+
+### Coverage Targets
+
+| Code Type | Target |
+|-----------|--------|
+| Critical business logic | 100% |
+| Public APIs | 90%+ |
+| General code | 80%+ |
+| Generated code | Exclude |
+
+### Excluding Generated Code from Coverage
+
+```go
+//go:generate mockgen -source=interface.go -destination=mock_interface.go
+
+// In coverage profile, exclude with build tags:
+// go test -cover -tags=!generate ./...
+```
+
+## HTTP Handler Testing
+
+```go
+func TestHealthHandler(t *testing.T) {
+    // Create request
+    req := httptest.NewRequest(http.MethodGet, "/health", nil)
+    w := httptest.NewRecorder()
+
+    // Call handler
+    HealthHandler(w, req)
+
+    // Check response
+    resp := w.Result()
+    defer resp.Body.Close()
+
+    if resp.StatusCode != http.StatusOK {
+        t.Errorf("got status %d; want %d", resp.StatusCode, http.StatusOK)
+    }
+
+    body, _ := io.ReadAll(resp.Body)
+    if string(body) != "OK" {
+        t.Errorf("got body %q; want %q", body, "OK")
+    }
+}
+
+func TestAPIHandler(t *testing.T) {
+    tests := []struct {
+        name       string
+        method     string
+        path       string
+        body       string
+        wantStatus int
+        wantBody   string
+    }{
+        {
+            name:       "get user",
+            method:     http.MethodGet,
+            path:       "/users/123",
+            wantStatus: http.StatusOK,
+            wantBody:   `{"id":"123","name":"Alice"}`,
+        },
+        {
+            name:       "not found",
+            method:     http.MethodGet,
+            path:       "/users/999",
+            wantStatus: http.StatusNotFound,
+        },
+        {
+            name:       "create user",
+            method:     http.MethodPost,
+            path:       "/users",
+            body:       `{"name":"Bob"}`,
+            wantStatus: http.StatusCreated,
+        },
+    }
+
+    handler := NewAPIHandler()
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            var body io.Reader
+            if tt.body != "" {
+                body = strings.NewReader(tt.body)
+            }
+
+            req := httptest.NewRequest(tt.method, tt.path, body)
+            req.Header.Set("Content-Type", "application/json")
+            w := httptest.NewRecorder()
+
+            handler.ServeHTTP(w, req)
+
+            if w.Code != tt.wantStatus {
+                t.Errorf("got status %d; want %d", w.Code, tt.wantStatus)
+            }
+
+            if tt.wantBody != "" && w.Body.String() != tt.wantBody {
+                t.Errorf("got body %q; want %q", w.Body.String(), tt.wantBody)
+            }
+        })
+    }
+}
+```
+
+## Testing Commands
+
+```bash
+# Run all tests
+go test ./...
+
+# Run tests with verbose output
+go test -v ./...
+
+# Run specific test
+go test -run TestAdd ./...
+
+# Run tests matching pattern
+go test -run "TestUser/Create" ./...
+
+# Run tests with race detector
+go test -race ./...
+
+# Run tests with coverage
+go test -cover -coverprofile=coverage.out ./...
+
+# Run short tests only
+go test -short ./...
+
+# Run tests with timeout
+go test -timeout 30s ./...
+
+# Run benchmarks
+go test -bench=. -benchmem ./...
+
+# Run fuzzing
+go test -fuzz=FuzzParse -fuzztime=30s ./...
+
+# Count test runs (for flaky test detection)
+go test -count=10 ./...
+```
+
+## Best Practices
+
+**DO:**
+- Write tests FIRST (TDD)
+- Use table-driven tests for comprehensive coverage
+- Test behavior, not implementation
+- Use `t.Helper()` in helper functions
+- Use `t.Parallel()` for independent tests
+- Clean up resources with `t.Cleanup()`
+- Use meaningful test names that describe the scenario
+
+**DON'T:**
+- Test private functions directly (test through public API)
+- Use `time.Sleep()` in tests (use channels or conditions)
+- Ignore flaky tests (fix or remove them)
+- Mock everything (prefer integration tests when possible)
+- Skip error path testing
+
+## Integration with CI/CD
+
+```yaml
+# GitHub Actions example
+test:
+  runs-on: ubuntu-latest
+  steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-go@v5
+      with:
+        go-version: '1.22'
+
+    - name: Run tests
+      run: go test -race -coverprofile=coverage.out ./...
+
+    - name: Check coverage
+      run: |
+        go tool cover -func=coverage.out | grep total | awk '{print $3}' | \
+        awk -F'%' '{if ($1 < 80) exit 1}'
+```
+
+**Remember**: Tests are documentation. They show how your code is meant to be used. Write them clearly and keep them up to date.