Function aggregate_diagnostics 

pub fn aggregate_diagnostics(
    classification: ClassificationStats,
    csg_failures: &FxHashMap<u32, Vec<BoolFailure>>,
    host_diags: &FxHashMap<u32, HostOpeningDiagnostic>,
    rect_fast: RectFastStats,
    worst_hosts_limit: usize,
    oversized_ref_drops: u64,
    unsupported_items: &FxHashMap<String, u64>,
) -> GeometryDiagnostics

Build a GeometryDiagnostics from drained router data. wasm-free so both the wasm/viewer path and a future native path can produce the same contract. The caller owns draining: the router accessors are destructive (mem::take), so drain once and pass the results here — do not double-take.