Mission Run Overview
Mission Run: Built-in re-vendor: pin lockfile + vendor command + drift gate
Implement ADR 2026-08-16-2 Option B: pin the open-packs built-in source by commit SHA + digest, add a 'charter pack vendor' command, and a CI drift gate that keeps the committed packs/built-in tree provably equal to the pin (#3504).
The committed packs/built-in tree can silently drift from its open-packs provenance source (as it just did: core moved 8 files past the recorded pin). ADR 2026-08-16-2 (amended 2026-10-11) keeps the tree committed and read-only, changed only via a pin bump, guarded by a drift gate. open-packs is now seeded+tagged (v0.1.0). Mission adds the core-side pin lockfile, the vendor command, the per-PR+release drift gate, and release re-verification, reusing landed primitives (core_compat, pack_clean_digest, regenerate-graph --pack-root). Out of scope: tree removal/materialization, packs/internal, the authoring flip.