A minimal, dependency-free logging port for gotd libraries.

A library writes structured records to a log.Logger; it never logs through a global and never imports a concrete logging framework. The consumer picks the backend by passing an adapter.

import (
    "github.com/gotd/log"
    "github.com/gotd/log/logslog" // stdlib log/slog backend, no extra deps
)

l := logslog.New(slog.Default())

if l.Enabled(ctx, log.LevelDebug) {
    l.Log(ctx, log.LevelDebug, "applying update",
        log.Int64("chat_id", chatID),
        log.Int("pts", pts),
    )
}

For ergonomic call sites, wrap a Logger in a Helper:

h := log.For(l) // log.For(nil) is a no-op Helper
h.Info(ctx, "connected", log.String("dc", dc))

• Logger is two methods: Enabled(ctx, level) and Log(ctx, level, msg, ...Attr). The Enabled gate lets callers skip building attributes on hot paths.
• Attributes don't box scalars. log.Int64, log.Bool, log.Duration, … store into a compact Value; only Any, Error and Time carry an interface{}.
• Levels match log/slog (Debug=-4 … Error=8) so adapters convert by casting.
• No global state. Nothing here registers or reads a process-wide logger.

Each backend adapter is a separate module so that its dependency never enters the core graph. Import only the one you use.

An adapter implements log.Logger by switching on Attr.Value.Kind() and mapping each kind to the backend's typed field; fall back to Value.Any() for KindAny. See logslog, logzap, logzerolog and loglogrus for references.