A new 'package' artifact kind builds a module's own code on a public base image and publishes it to the mesh's package registry by version (hq ADR 0076) — the SDK above all, which the toolchain is built from and so cannot be built in the toolchain. The credential a build needs to resolve or publish packages is rendered as an .npmrc (basic auth, hq ADR 0048) and given to an image build as a buildkit secret, never a layer, so a token is not baked into the toolchain image. Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx