Module engine 

Graph-engine abstraction. The default backend is SQLite (the one used everywhere in the codebase). A feature-gated cozo backend mirrors the call edges into an embedded Datalog database so impact queries can be expressed as a recursive Datalog rule.

The trait is intentionally small: it only covers the call-graph traversal that benefits from a different algebra. Symbol lookup, references, and outlines all stay on SQLite — they’re already fast there.

Structs

SqliteEngine

Traits

GraphEngine

Functions

select_engine

Open the requested engine. The cozo variant returns an error unless the cozo Cargo feature is enabled. We deliberately do not silently fall back to SQLite — if the user asked for Cozo, they should see the gap.