The pkg provider has no design document: 3.5.x has an entry for every provider but this one #868

Feature: #836 — the pkg provider

Found 2026-09-08 during #647, the sealed-contract documentation pass: every provider has a docs/architecture/3.5.x-<name>-provider.md except pkg. Its resource, its package-manager delegation, its purl surface, and its receipt shape are described nowhere, so the sealed-shape sentence #647 added to eight documents has no home for the ninth.

pkg is not a small provider: eight announced methods, the platform's package-manager layer beneath it, a sealed pkg.Resource, and two open high-priority bugs against its identity surface (#813, #814).

Work

1. docs/architecture/3.5.17-pkg-provider.md in the form the others take: thesis, design points, API surface, the resource's sealed shape and addressing, the receipt, and the platform delegation.
2. Its status file.
3. 3.5-provider-catalog.md's pkg row links it.

Acceptance

• The document exists and follows the 3.5.x form
• It states the sealed shape as the other eight now do (Closure: the design record states the sealed contract #647)
• It describes the purl surface as ruled, so pkg.Resource rejects the canonical purl form its doc promises: "pkg:winget/Vim/Vim?scope=machine" fails as unknown package manager "pkg" #813's fix has a written contract to satisfy
• The catalog row links it; the status file records the state

Plan and design documents

Epic: #815 · Feature: #836