go-modern

name	go-modern
description	Write idiomatic, modern Go (1.25+/1.26) using current language and stdlib features. Use when authoring or reviewing Go code, choosing between stdlib and third-party helpers, working with generics, iterators, contexts, or error wrapping in this workspace.

Modern Go

Write Go that reads like the standard library: small, explicit, and boring in the best way. Target the workspace Go version (1.25+/1.26).

When to use

• Implementing or refactoring Go packages, services, or CLIs.
• Reviewing Go for idiomatic style and current stdlib usage.
• Deciding between stdlib, a RonyKIT x/* helper, and a third-party package.

Core idioms

• Accept interfaces, return structs. Keep interfaces small and defined by the consumer, not the producer.
• Errors: wrap with fmt.Errorf("...: %w", err); inspect with errors.Is / errors.As. In this workspace prefer rony/errs for domain errors.
• Context first. ctx context.Context is the first parameter; never store it in a struct. Honor cancellation and deadlines.
• Zero values are useful. Design types so the zero value is ready to use.
• Generics for containers/algorithms only. Don't reach for type parameters when a concrete type or a small interface is clearer.

Use current stdlib

• Iterators (iter.Seq, range-over-func), slices, maps, cmp for collection work instead of hand-rolled loops.
• min/max/clear builtins.
• for i := range n for counted loops.
• errors.Join to combine multiple failures.
• context.WithoutCancel, WithDeadlineCause, and AfterFunc where they fit.
• log/slog for structured logging (or the workspace x/telemetry/logkit).

Package selection (this workspace)

Before importing a third-party or stdlib helper, check for a RonyKIT equivalent: IDs/JSON-byte casts/string↔number/case/collections → x/rkit; config → x/settings; DI → x/di; errors → rony/errs; logging → x/telemetry/logkit. Durable workflows: flow only — never import go.temporal.io/sdk directly. See knowledge://ronyup/architecture/package-selection.

Concurrency

• Start a goroutine only when you control its lifetime and shutdown.
• Prefer errgroup / bounded worker pools over unbounded go calls.
• Protect shared state with the smallest possible critical section; prefer channels for ownership transfer, mutexes for protecting fields.
• Always test with -race for concurrent code.

Checklist before "done"

• gofmt/goimports clean, go vet passes, golangci-lint clean.
• No naked panic in library code; errors returned and wrapped.
• Exported identifiers have doc comments starting with the identifier name.