# go-context

Enforces idiomatic context.Context rules in Go, covering parameter placement, cancellation deadlines, and request data boundaries.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1200 installs · ★ 181
- Author: cxuu
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/cxuu/golang-skills/tree/HEAD/skills/go-context/SKILL.md
- Updated: 2026-06-20
- HTML: https://affpapa.org/en/nevibecode/skills/go-context

## What it does

The skill instructs the agent to follow standard Go conventions for `context.Context`. It enforces placing context as the first function parameter, prohibits storing contexts inside struct fields, and rejects custom context interfaces. Application data follows a strict priority order: explicit function arguments come first, while context values remain reserved for request IDs, trace tokens, and auth data.

It details patterns for cancellation via `select` on `<-ctx.Done()`, immediate `defer cancel()` calls on derived timeouts, and pointers to `references/PATTERNS.md` for HTTP contexts. Because `context` joined the standard library in Go 1.7, no external dependencies are needed.

The skill does not manage goroutine lifecycles or synchronization primitives, so concurrent worker pools require the companion go-concurrency skill. Storing context in a struct is treated as bad practice, allowed only when matching fixed standard library or third-party interfaces.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-context -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/go-context/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/go-context/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-context -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/go-context/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-context -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/go-context/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install cxuu/golang-skills go-context
```

2. **Manually: put the files in place**
- File: `.github/skills/go-context/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-context -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/cxuu/golang-skills --path skills/go-context
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/go-context/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-context -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/cxuu/golang-skills/tree/HEAD/skills/go-context/SKILL.md

## When to use it
- place `context.Context` as the first function parameter
- remove context fields from structs in favor of method parameters
- handle operation timeouts and cancellation signals cleanly
- prevent using context values for regular function arguments

## Example prompts
- Review the Worker struct: remove the context field and pass it to methods instead
- Add a 5-second timeout to this API call using context.WithTimeout and defer cancel()
- Check my function signatures in internal/service to make sure ctx is the first argument

## Source text · SKILL.md · Apache-2.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 840e7b8ad8e1599f.

BEGIN THIRD-PARTY FILE 840e7b8ad8e1599f
````text
---
name: go-context
description: Use when working with context.Context in Go — placement in signatures, propagating cancellation and deadlines, and storing values in context vs parameters. Also use when cancelling long-running operations, setting timeouts, or passing request-scoped data, even if they don't mention context.Context directly. Does not cover goroutine lifecycle or sync primitives (see go-concurrency).
---

# Go Context Usage

> Compatibility: `context` has been in the standard library since Go 1.7.

## Resource Routing

- `references/PATTERNS.md` - Read when deriving contexts, checking cancellation, handling HTTP request contexts, or using typed context-value keys.

## Context as First Parameter

Functions that use a Context should accept it as their **first parameter**:

```go
func F(ctx context.Context, /* other arguments */) error
func ProcessRequest(ctx context.Context, req *Request) (*Response, error)
```

This is a strong convention in Go that makes context flow visible and consistent
across codebases.

---

## Don't Store Context in Structs

Do not add a Context member to a struct type. Instead, pass `ctx` as a parameter
to each method that needs it:

```go
// Bad: Context stored in struct
type Worker struct {
    ctx context.Context  // Don't do this
}

// Good: Context passed to methods
type Worker struct{ /* ... */ }

func (w *Worker) Process(ctx context.Context) error {
    // Context explicitly passed — lifetime clear
}
```

**Exception**: Methods whose signature must match an interface in the standard
library or a third-party library may need to work around this.

---

## Don't Create Custom Context Types

Do not create custom Context types or use interfaces other than `context.Context`
in function signatures:

```go
// Bad: Custom context type
type MyContext interface {
    context.Context
    GetUserID() string
}

// Good: Use standard context.Context with value extraction
func Process(ctx context.Context) error {
    userID := GetUserID(ctx)
}
```

---

## Where to Put Application Data

Consider these options in order of preference:

1. **Function parameters** — most explicit and type-safe
2. **Receiver** — for data that belongs to the type
3. **Globals** — for truly global configuration (use sparingly)
4. **Context value** — only for request-scoped data

Context values are appropriate for:
- Request IDs and trace IDs
- Authentication/authorization info that flows with requests
- Deadlines and cancellation signals

Context values are **not** appropriate for:
- Optional function parameters
- Data that could be passed explicitly
- Configuration that doesn't vary per-request

---

## Common Patterns

### Deriving Contexts

Always `defer cancel()` immediately after creating a derived context:

```go
ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
defer cancel()
```
````
END THIRD-PARTY FILE 840e7b8ad8e1599f

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