Decides the architecture for SQL in advanced mode (Q1/Q2/Q4):
SQL is authored as grammar within the unified grammar tree
(ADR-0024) and parsed by the existing walker — not a separate
batch parser — so SQL gets the same completion, highlighting,
hints, and parse-error reporting as the DSL. Mode gates the
SQL forms. DDL routes through the typed Command executor
(metadata and the playground type vocabulary preserved); DML
and SELECT execute as validated SQL. Engine-neutral posture;
DSL→SQL teaching echo; phased plan.
Supersedes ADR-0001's sqlparser-rs reservation. Ticks Q4;
updates the ADR index and the Q1/Q2 notes. handoff-24 orients
the implementation session at Phase 1.
claude@clouddev1