Official libraries

The first-party, opt-in libraries: tier 1 of the stability scale (§1, “The stability layers”). They are specifications that evolve (HTTP had 3 versions; a regex engine swaps algorithms; the collection of structures grows), so they have their own cadence (semver/changelog/bugfix), distinct from the slow core. They ship with the toolchain as a known-good snapshot, with zero weight until use, and update independently of it through the first-party registry (the distribution this requires is a tooling phase, §21). The curation bar follows the core’s in philosophy (colorless, no null, honest names, structural satisfaction), and loosens only in scope (they can be specialized). Each one depends only downward (tier 0: net/io/crypto/collections/…), never a framework (tier 2) nor another official lib, except by explicit note.

In this file (under construction): http (below); next come regex and containers.