Charles Xu

Use when reviewing Go code or checking code against community style standards. Also use proactively before submitting a Go PR or when reviewing any Go code changes, even if the user doesn't explicitly request a style review. Does not cover language-specific syntax — delegates to specialized skills.

Use when writing concurrent Go code — goroutines, channels, mutexes, or thread-safety guarantees. Also use when parallelizing work, fixing data races, or protecting shared state, even if the user doesn't explicitly mention concurrency primitives. Does not cover context.Context patterns (see go-context).

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).

Use when writing conditionals, loops, or switch statements in Go — including if with initialization, early returns, for loop forms, range, switch, type switches, and blank identifier patterns. Also use when writing a simple if/else or for loop, even if the user doesn't mention guard clauses or variable scoping. Does not cover error flow patterns (see go-error-handling).

Use when working with Go slices, maps, or arrays — choosing between new and make, using append, declaring empty slices (nil vs literal for JSON), implementing sets with maps, and copying data at boundaries. Also use when building or manipulating collections, even if the user doesn't ask about allocation idioms. Does not cover concurrent data structure safety (see go-concurrency).

Use when declaring or initializing Go variables, constants, structs, or maps — including var vs :=, reducing scope with if-init, formatting composite literals, designing iota enums, and using any instead of interface{}. Also use when writing a new struct or const block, even if the user doesn't ask about declaration style. Does not cover naming conventions (see go-naming).

Use when hardening Go code at API boundaries — copying slices/maps, verifying interface compliance, using defer for cleanup, time.Time/time.Duration, or avoiding mutable globals. Also use when reviewing for robustness concerns like missing cleanup or unsafe crypto usage, even if the user doesn't mention "defensive programming." Does not cover error handling strategy (see go-error-handling).

Use when writing or reviewing documentation for Go packages, types, functions, or methods. Also use proactively when creating new exported types, functions, or packages, even if the user doesn't explicitly ask about documentation. Does not cover code comments for non-exported symbols (see go-style-core).

Use when writing Go code that returns, wraps, or handles errors — choosing between sentinel errors, custom types, and fmt.Errorf (%w vs %v), structuring error flow, or deciding whether to log or return. Also use when propagating errors across package boundaries or using errors.Is/As, even if the user doesn't ask about error strategy. Does not cover panic/recover patterns (see go-defensive).

Use when designing a Go constructor or factory function with optional configuration — especially with 3+ optional parameters or extensible APIs. Also use when building a New* function that takes many settings, even if they don't mention "functional options" by name. Does not cover general function design (see go-functions).

Use when organizing functions within a Go file, formatting function signatures, designing return values, or following Printf-style naming conventions. Also use when a user is adding or refactoring any Go function, even if they don't mention function design or signature formatting. Does not cover functional options constructors (see go-functional-options).

Use when deciding whether to use Go generics, writing generic functions or types, choosing constraints, or picking between type aliases and type definitions. Also use when a user is writing a utility function that could work with multiple types, even if they don't mention generics explicitly. Does not cover interface design without generics (see go-interfaces).

Use when defining or implementing Go interfaces, designing abstractions, creating mockable boundaries for testing, or composing types through embedding. Also use when deciding whether to accept an interface or return a concrete type, or using type assertions or type switches, even if the user doesn't explicitly mention interfaces. Does not cover generics-based polymorphism (see go-generics).

Use when setting up linting for a Go project, configuring golangci-lint, or adding Go checks to a CI/CD pipeline. Also use when starting a new Go project and deciding which linters to enable, even if the user only asks about "code quality" or "static analysis" without mentioning specific linter names. Does not cover code review process (see go-code-review).

Use when choosing a logging approach, configuring slog, writing structured log statements, or deciding log levels in Go. Also use when setting up production logging, adding request-scoped context to logs, or migrating from log to slog, even if the user doesn't explicitly mention logging. Does not cover error handling strategy (see go-error-handling).

Use when naming any Go identifier — packages, types, functions, methods, variables, constants, or receivers — to ensure idiomatic, clear names. Also use when a user is creating new types, packages, or exported APIs, even if they don't explicitly ask about naming conventions. Does not cover package organization (see go-packages).

Use when creating Go packages, organizing imports, managing dependencies, or deciding how to structure Go code into packages. Also use when starting a new Go project or splitting a growing codebase into packages, even if the user doesn't explicitly ask about package organization. Does not cover naming individual identifiers (see go-naming).

Use when optimizing Go code, investigating slow performance, or writing performance-critical sections. Also use when a user mentions slow Go code, string concatenation in loops, or asks about benchmarking, even if the user doesn't explicitly mention performance patterns. Does not cover concurrent performance patterns (see go-concurrency).

Use when working with Go formatting, line length, nesting, naked returns, semicolons, or core style principles. Also use when a style question isn't covered by a more specific skill, even if the user doesn't reference a specific style rule. Does not cover domain-specific patterns like error handling, naming, or testing (see specialized skills). Acts as fallback when no more specific style skill applies.

Use when writing, reviewing, or improving Go test code — including table-driven tests, subtests, parallel tests, test helpers, test doubles, and assertions with cmp.Diff. Also use when a user asks to write a test for a Go function, even if they don't mention specific patterns like table-driven tests or subtests. Does not cover benchmark performance testing (see go-performance).