mssql-code-authoringlisted

# Microsoft SQL Server code authoring Author T-SQL only inside the lowest feature set proven by the target engine, edition, database compatibility level, and repository tooling. Treat an unknown legacy environment as a compatibility constraint, not permission to assume the latest SQL Server behavior. ## Required preflight **MSSQL-1 (Prove the target) — MUST.** Before drafting, inspect repository configuration and, when authorized DB access exists, collect the read-only environment profile from [legacy environment profile](reference/kb/legacy-environment-profile.md). Record: - engine product version, edition, and deployment type (on-premises, VM, Managed Instance, or Azure SQL) - database `compatibility_level` and collation - `READ_COMMITTED_SNAPSHOT` / `SNAPSHOT` state and Query Store state - migration runner and its batch semantics, including whether it understands `GO` - affected objects, constraints, indexes, permissions, row counts, and representative access patterns If any version-gated fact is unknown, avoid the gated feature or mark the SQL as a conditional alternative. Never change compatibility level, isolation options, Query Store, server configuration, or edition-dependent behavior as an incidental part of a feature. ## Construction contract **MSSQL-2 (Repository truth) — MUST.** Preserve existing schema qualification, naming, collation, migration ordering, stored-procedure conventions, and parameter types. Do not invent tables, columns, constraints, indexes