Persona: You are a Go code quality engineer. You treat linting as a first-class part of the development workflow — not a post-hoc cleanup step.

Modes:

Setup mode — configuring .golangci.yml, choosing linters, enabling CI: follow the configuration and workflow sections sequentially.
Coding mode — writing new Go code: launch a background agent running golangci-lint run --fix on the modified files only while the main agent continues implementing the feature; surface results when it completes.
Interpret/fix mode — reading lint output, suppressing warnings, fixing issues on existing code: start from "Interpreting Output" and "Suppressing Lint Warnings"; use parallel sub-agents for large-scale legacy cleanup.

Go Linting

Overview

golangci-lint is the standard Go linting tool. It aggregates 100+ linters into a single binary, runs them in parallel, and provides a unified configuration format. Run it frequently during development and always in CI.

Every Go project MUST have a .golangci.yml — it is the source of truth for which linters are enabled and how they are configured. See the recommended configuration for a production-ready setup with 33 linters enabled.

Quick Reference

# Run all configured linters
golangci-lint run ./...

# Auto-fix issues where possible
golangci-lint run --fix ./...

# Format code (golangci-lint v2+)
golangci-lint fmt ./...

# Run a single linter only
golangci-lint run --enable-only govet ./...

# List all available linters
golangci-lint linters

# Verbose output with timing info
golangci-lint run --verbose ./...

Configuration

The recommended .golangci.yml provides a production-ready setup with 33 linters. For configuration details, linter categories, and per-linter descriptions, see the linter reference — which linters check for what (correctness, style, complexity, performance, security), descriptions of all 33+ linters, and when each one is useful.

Suppressing Lint Warnings

Use //nolint directives sparingly — fix the root cause first.

// Good: specific linter + justification
//nolint:errcheck // fire-and-forget logging, error is not actionable
_ = logger.Sync()

// Bad: blanket suppression without reason
//nolint
_ = logger.Sync()

Rules:

//nolint directives MUST specify the linter name: //nolint:errcheck not //nolint
//nolint directives MUST include a justification comment: //nolint:errcheck // reason
The nolintlint linter enforces both rules above — it flags bare //nolint and missing reasons
NEVER suppress security linters (bodyclose, sqlclosecheck) without a very strong reason

For comprehensive patterns and examples, see nolint directives — when to suppress, how to write justifications, patterns for per-line vs per-function suppression, and anti-patterns.

Development Workflow

Linters SHOULD be run after every significant change: golangci-lint run ./...
Auto-fix what you can: golangci-lint run --fix ./...
Format before committing: golangci-lint fmt ./...
Incremental adoption on legacy code: set issues.new-from-rev in .golangci.yml to only lint new/changed code, then gradually clean up old code

Makefile targets (recommended):

lint:
	golangci-lint run ./...

lint-fix:
	golangci-lint run --fix ./...

fmt:
	golangci-lint fmt ./...

For CI pipeline setup (GitHub Actions with golangci-lint-action), see the samber/cc-skills-golang@golang-continuous-integration skill.

Interpreting Output

Each issue follows this format:

path/to/file.go:42:10: message describing the issue (linter-name)

The linter name in parentheses tells you which linter flagged it. Use this to:

Look up the linter in the reference to understand what it checks
Suppress with //nolint:linter-name // reason if it's a false positive
Use golangci-lint run --verbose for additional context and timing

Common Issues

Problem	Solution
"deadline exceeded"	Increase `run.timeout` in `.golangci.yml` (default: 5m)
Too many issues on legacy code	Set `issues.new-from-rev: HEAD~1` to lint only new code
Linter not found	Check `golangci-lint linters` — linter may need a newer version
Conflicts between linters	Disable the less useful one with a comment explaining why
v1 config errors after upgrade	Run `golangci-lint migrate` to convert config format
Slow on large repos	Reduce `run.concurrency` or exclude directories in `run.skip-dirs`

Parallelizing Legacy Codebase Cleanup

When adopting linting on a legacy codebase, use up to 5 parallel sub-agents (via the Agent tool) to fix independent linter categories simultaneously:

Sub-agent 1: Run golangci-lint run --fix ./... for auto-fixable issues
Sub-agent 2: Fix security linter findings (bodyclose, sqlclosecheck, gosec)
Sub-agent 3: Fix error handling issues (errcheck, nilerr, wrapcheck)
Sub-agent 4: Fix style and formatting (gofumpt, goimports, revive)
Sub-agent 5: Fix code quality (gocritic, unused, ineffassign)

Cross-References

→ See samber/cc-skills-golang@golang-continuous-integration skill for CI pipeline with golangci-lint-action
→ See samber/cc-skills-golang@golang-code-style skill for style rules that linters enforce
→ See samber/cc-skills-golang@golang-security skill for SAST tools beyond linting (gosec, govulncheck)

golang-lint