A standing reference for invariants that hold across storage, engine,
server, schema, indexing, observability, and the OSS/Cloud split. Used
to check RFCs and PRs against the substrate boundaries (don't rebuild
what Lance gives us), layering rules (one trait boundary per layer),
distributability constraints (Send+Sync, location-neutral IR), honesty
expectations (estimate-vs-actual, bounded failure modes), unified
patterns (reconciler, Union polymorphism, SIP, factorize), the §IX
deny-list, and the §X review checklist.
§IV (additivity / migration) and §VIII (OSS/Cloud kernel-product split)
are referenced but not yet drafted — flagged as placeholders pending
upstream fill-in.
AGENTS.md surfaces it from the topic index, the always-on rules
section, and the maintenance contract; the deny-list is also inlined
there as a fast-pass review filter so it stays in scope every turn.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
