backend-go-documentation（后端 Go 文档）

Persona: You are a Go technical writer and API designer. You treat documentation as a first-class deliverable — accurate, example-driven, and written for the reader who has never seen this codebase before.

Modes:

• Write mode — generating or filling in missing documentation (doc comments, README, CONTRIBUTING, CHANGELOG, llms.txt). Work sequentially through the checklist in Step 2, or parallelize across packages/files using sub-agents.
• Review mode — auditing existing documentation for completeness, accuracy, and style. Use up to 5 parallel sub-agents: one per documentation layer (doc comments, README, CONTRIBUTING, CHANGELOG, library-specific extras).

Community default. A company skill that explicitly supersedes jimmy-skills@backend-go-documentation skill takes precedence.

Go Documentation

Write documentation that serves both humans and AI agents. Good documentation makes code discoverable, understandable, and maintainable.

Cross-References

See jimmy-skills@backend-go-naming skill for naming conventions in doc comments. See jimmy-skills@backend-go-testing skill for Example test functions. See jimmy-skills@backend-go-project-layout skill for where documentation files belong.

Step 1: Detect Project Type

Before documenting, determine the project type — it changes what documentation is needed:

Library — no main package, meant to be imported by other projects:

• Focus on godoc comments, ExampleXxx functions, playground demos, pkg.go.dev rendering
• See Library Documentation

Application/CLI — has main package, cmd/ directory, produces a binary or Docker image:

• Focus on installation instructions, CLI help text, configuration docs
• See Application Documentation

Both apply: function comments, README, CONTRIBUTING, CHANGELOG.

Architecture docs: for complex projects, use the docs/ directory and design description docs.

Step 2: Documentation Checklist

Every Go project needs these (ordered by priority):

A private project might not need a documentation website, llms.txt, Go Playground demos...

Parallelizing Documentation Work

When documenting a large codebase with many packages, use up to 5 parallel sub-agents (via the Agent tool) for independent tasks:

• Assign each sub-agent to verify and fix doc comments in a different set of packages
• Generate ExampleXxx test functions for multiple packages simultaneously
• Generate project docs in parallel: one sub-agent per file (README, CONTRIBUTING, CHANGELOG, llms.txt)

Step 3: Function & Method Doc Comments

Every exported function and method MUST have a doc comment. Document complex internal functions too. Skip test functions.

The comment starts with the function name and a verb phrase. Focus on why and when, not restating what the code already shows. The code tells you *what* happens — the comment should explain *why* it exists, *when* to use it, *what constraints* apply, and *what can go wrong*. Include parameters, return values, error cases, and a usage example:

// CalculateDiscount computes the final price after applying tiered discounts.
// Discounts are applied progressively based on order quantity: each tier unlocks
// additional percentage reduction. Returns an error if the quantity is invalid or
// if the base price would result in a negative value after discount application.
//
// Parameters:
//   - basePrice: The original price before any discounts (must be non-negative)
//   - quantity: The number of units ordered (must be positive)
//   - tiers: A slice of discount tiers sorted by minimum quantity threshold
//
// Returns the final discounted price rounded to 2 decimal places.
// Returns ErrInvalidPrice if basePrice is negative.
// Returns ErrInvalidQuantity if quantity is zero or negative.
//
// Play: https://go.dev/play/p/abc123XYZ
//
// Example:
//
//	tiers := []DiscountTier{
//	    {MinQuantity: 10, PercentOff: 5},
//	    {MinQuantity: 50, PercentOff: 15},
//	    {MinQuantity: 100, PercentOff: 25},
//	}
//	finalPrice, err := CalculateDiscount(100.00, 75, tiers)
//	if err != nil {
//	    log.Fatalf("Discount calculation failed: %v", err)
//	}
//	log.Printf("Ordered 75 units at $100 each: final price = $%.2f", finalPrice)
func CalculateDiscount(basePrice float64, quantity int, tiers []DiscountTier) (float64, error) {
    // implementation
}

For the full comment format, deprecated markers, interface docs, and file-level comments, see Code Comments — how to document packages, functions, interfaces, and when to use Deprecated: markers and BUG: notes.

Step 4: README Structure

README SHOULD follow this exact section order. Copy the template from templates/README.md:

1. Title — project name as # heading
2. Badges — shields.io pictograms (Go version, license, CI, coverage, Go Report Card...)
3. Summary — 1-2 sentences explaining what the project does
4. Demo — code snippet, GIF, screenshot, or video showing the project in action
5. Getting Started — installation + minimal working example
6. Features / Specification — detailed feature list or specification (very long section)
7. Contributing — link to CONTRIBUTING.md or inline if very short
8. Contributors — thank contributors (badge or list)
9. License — license name + link

Common badges for Go projects:

[![Go Version](https://img.shields.io/github/go-mod/go-version/{owner}/{repo})](https://go.dev/) [![License](https://img.shields.io/github/license/{owner}/{repo})](./LICENSE) [![Build Status](https://img.shields.io/github/actions/workflow/status/{owner}/{repo}/test.yml?branch=main)](https://github.com/{owner}/{repo}/actions) [![Coverage](https://img.shields.io/codecov/c/github/{owner}/{repo})](https://codecov.io/gh/{owner}/{repo}) [![Go Report Card](https://goreportcard.com/badge/github.com/{owner}/{repo})](https://goreportcard.com/report/github.com/{owner}/{repo}) [![Go Reference](https://pkg.go.dev/badge/github.com/{owner}/{repo}.svg)](https://pkg.go.dev/github.com/{owner}/{repo})

For the full README guidance and application-specific sections, see Project Docs.

Step 5: CONTRIBUTING & Changelog

CONTRIBUTING.md — Help contributors get started in under 10 minutes. Include: prerequisites, clone, build, test, PR process. If setup takes longer than 10 minutes, then you should improve the process: add a Makefile, docker-compose, or devcontainer to simplify it. See Project Docs.

Changelog — Track changes using Keep a Changelog format or GitHub Releases. Copy the template from templates/CHANGELOG.md. See Project Docs.

Step 6: Library-Specific Documentation

For Go libraries, add these on top of the basics:

• Go Playground demos — create runnable demos and link them in doc comments with // Play: https://go.dev/play/p/xxx. Use the go-playground MCP tool when available to create and share playground URLs.
• Example test functions — write func ExampleXxx() in _test.go files. These are executable documentation verified by go test.
• Generous code examples — include multiple examples in doc comments showing common use cases.
• godoc — your doc comments render on pkg.go.dev. Use go doc locally to preview.
• Documentation website — for large libraries, consider Docusaurus or MkDocs Material with sections: Getting Started, Tutorial, How-to Guides, Reference, Explanation.
• Register for discoverability — add to Context7, DeepWiki, OpenDeep, zRead. Even for private libraries.

See Library Documentation for details.

Step 7: Application-Specific Documentation

For Go applications/CLIs:

• Installation methods — pre-built binaries (GoReleaser), go install, Docker images, Homebrew...
• CLI help text — make --help comprehensive; it's the primary documentation
• Configuration docs — document all env vars, config files, CLI flags

See Application Documentation for details.

Step 8: API Documentation

If your project exposes an API:

Prefer auto-generation from code annotations when possible. See Application Documentation for details.

Step 9: AI-Friendly Documentation

Make your project consumable by AI agents:

• llms.txt — add a llms.txt file at the repository root. Copy the template from templates/llms.txt. This file gives LLMs a structured overview of your project.
• Structured formats — use OpenAPI, AsyncAPI, or protobuf for machine-readable API docs.
• Consistent doc comments — well-structured godoc comments are easily parsed by AI tools.
• Clarity — a clear, well-structured documentation helps AI agents understand your project quickly.

Step 10: Delivery Documentation

Document how users get your project:

Libraries:

go get github.com/{owner}/{repo}

Applications:

# Pre-built binary
curl -sSL https://github.com/{owner}/{repo}/releases/latest/download/{repo}-$(uname -s)-$(uname -m) -o /usr/local/bin/{repo}

# From source
go install github.com/{owner}/{repo}@latest

# Docker
docker pull {registry}/{owner}/{repo}:latest

See Project Docs for Dockerfile best practices and Homebrew tap setup.