rules: Skill for Claude Code

.claude/skills/go-practices/SKILL.md

go-practices is a skill for Claude Code from eser/rules. It costs 30 tokens per session (182 once invoked), scanned A, original, Apache-2.0.

A set of Go development conventions covering project structure, hexagonal architecture, errors, tests, and observability. It describes how business logic and external systems should be separated.

In plain words
What is it for?
Use it when writing or reviewing Go services, especially their interfaces, adapters, error handling, parallel tests, and OpenTelemetry instrumentation.
Why use it?
It provides consistent rules for organizing Go services and checking them with tests and race detection.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is eser/rules's own configuration. It tells Claude Code how to work on rules itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything rules configures →

View source ↗ eser/rules
Reuse

Borrowing it

Nothing to install: this file belongs to eser/rules. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/eser/rules/main/.claude/skills/go-practices/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/eser/rules

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for go-practices

README.md
[![agentmods](https://agentmods.dev/badge/skills/eser/rules/go-practices/github.svg)](https://agentmods.dev/skills/eser/rules/go-practices)
Your own site
<a href="https://agentmods.dev/skills/eser/rules/go-practices"><img src="https://agentmods.dev/badge/skills/eser/rules/go-practices/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for go-practices

Your own site · 80×15
<a href="https://agentmods.dev/skills/eser/rules/go-practices"><img src="https://agentmods.dev/badge/skills/eser/rules/go-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 182 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00030 $0.00182
Opus 5.5 $0.00012 $0.00073
Sonnet 5.5 $0.00006 $0.00036
Haiku 4.5 $0.00003 $0.00018

Measured 2mo ago against content hash 09028d3817d5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

go-practices scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/go-practices/SKILL.md · 27 lines

What it actually says

go-practices

Quick Start

  1. Follow hexagonal architecture: business logic in pkg/api/business/, adapters in pkg/api/adapters/
  2. Use snake_case for all Go files
  3. Wrap errors: fmt.Errorf("%w: %w", ErrSentinelError, err)
  4. Run tests with race detection: go test -race ./...

Key Principles

  • Business logic has NO external dependencies
  • All external interactions through interfaces
  • Composition via AppContext (composition root)
  • Table-driven tests with t.Parallel()
  • OpenTelemetry for observability

References

See rules.md for complete conventions.

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2mo ago First seen · 27 lines · 30 tokens per session scan A 09028d3817d5

Subscribe to this mod's changes

go-practices is a skill published in the GitHub repository eser/rules (53 stars, last pushed 10mo ago), licensed Apache-2.0. It adds 30 tokens to every session and 182 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

golang-pro

Implements concurrent Go patterns using goroutines and channels, designs and builds microservices with gRPC or REST, optimizes Go application performance with pprof, and enforces idiomatic Go with generics, interfaces, and robust error handling. Use when building Go applications requiring concurrent programming…

Jeffallan/claude-skills · 95 tokens

golang-graphql

Implements GraphQL APIs in Golang using gqlgen or graphql-go. Apply when building GraphQL servers, designing schemas, writing resolvers, handling subscriptions, or integrating GraphQL with existing Go HTTP services. Also apply when the codebase imports github.com/99designs/gqlgen or github.com/graph-gophers/graphql-go.

samber/cc-skills-golang · 77 tokens

golang-grpc

Provides gRPC usage guidelines, protobuf organization, and production-ready patterns for Golang microservices. Use when implementing, reviewing, or debugging gRPC servers/clients, writing proto files, setting up interceptors, handling gRPC errors with status codes, configuring TLS/mTLS, testing with bufconn, or…

samber/cc-skills-golang · 72 tokens

golang-swagger

Golang OpenAPI/Swagger documentation with swaggo/swag — annotation comments (@Summary, @Param, @Success, @Router, @Security), swag init code generation, framework integrations (gin, echo, fiber, chi, net/http), security definitions (Bearer/JWT, OAuth2, API key), and struct tags (swaggertype, enums, example…

samber/cc-skills-golang · 146 tokens

printing-press

Set up a new integration, connector, or CLI binding for any API. Wrap or generate a ship-ready Go CLI from an OpenAPI, HAR, or Postman spec via the lean research -> generate -> build -> shipcheck loop. Use when the user says build a CLI, wrap this API, set up a new integration, add a connector, integrate with a…

mvanhorn/cli-printing-press · 86 tokens

goframe-v2

GoFrame development skill. TRIGGER when writing/modifying Go files, implementing services, creating APIs, or database operations. DO NOT TRIGGER for frontend/shell scripts.

hashgraph-online/awesome-codex-plugins · 40 tokens