Behavioral Contract

The canonical contract is maintained at the repository root: read BEHAVIORAL_CONTRACT.md.

It fixes observable semantics for values and three-valued predicates, names and grouping, aggregates, statement effects, statistics and planning, persistent storage, B+Tree indexes, transactions and recovery, VACUUM, and HOT.

This is the normative prose boundary. The behavior matrix points from those claims to executable tests, while Differences from PostgreSQL prevents the bounded contract from being mistaken for PostgreSQL compatibility.