ReifyDB Query Language: lexer, parser, AST, logical and physical planning, optimisation, and the instruction stream consumed by the engine VM. This is the full pipeline that turns a source string into something executable.
The crate exposes the AST shape so external tooling (formatters, linters, the explain renderer) can inspect queries without re-parsing, and exposes a stable fingerprint over compiled plans that the engine uses for plan caching. Diagnostics produced here carry source-fragment context so user-visible failures can point at the offending span.
Invariant: planner output is decoupled from any specific storage backend. The physical plan is expressed in terms
of core::interface/ traits; concrete backend selection happens later, in the engine. Reaching into a specific
backend from inside the planner couples this crate to the storage tier and breaks the layering that lets core
avoid cycles.