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 d

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 : 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: 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: 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: Checking Cancellation Context Immutability Contexts are immutable — it's safe to pass the same ctx to multiple concurrent calls that share the same deadline and cancellation signal. Related Skills Goroutine coordination : See [go concurrency](../go concurrency/SKILL.md) when using context for goroutine cancellation, select based timeouts, or errgroup Error handling : See [go error handling](../go error handling/SKILL.md) when deciding how to wrap or return ctx.Err() cancellation errors Interface design : See [go interfaces](../go interfaces/SKILL.md) when designing APIs that accept context alongside interfaces Request scoped logging : See [go logging](../go logging/SKILL.md) when injecting loggers into context or adding request IDs to structured log output

go-context