Function closed_program_reachability 

pub fn closed_program_reachability(
    build: &ModuleGraphBuild,
    entrypoint: &Path,
) -> SymbolReachability

Resolve export demand across a closed graph to a monotone fixpoint.

Selective and namespace imports retain exact members when structural analysis proves them. Wildcard flattening and every unresolved edge widen the target to its complete namespace. Import edges and module initializers are never removed by this pass.