Implementation handoff: a SQL `select` typed in advanced mode
parses, runs, and renders end to end; the same line in simple
mode lights up the precise "this is SQL" hint instead. ADR-0031
(the SQL expression grammar) and ADR-0030 Phase 1 ("Foundations
+ first SELECT") landed across five commits. Tests 1240 → 1260,
clippy clean.
The handoff records: the walker mode gate + `is_advanced_only`
set, the `ast_builder` source-param sweep, `Command::Select`
carrying the validated SQL text, the `data::SELECT` shape, the
worker `Request::RunSelect` round-trip, the ambient mode
threading through completion / overlay / validity indicator,
the autonomous calls made during execution (FROM optional,
implicit alias unsupported, etc.), and the seams the next
session uses to take up ADR-0030 Phase 2 (full SELECT) — which
gets its own focused ADR before code, per ADR-0030 §3.