Function build_archify_document 

pub fn build_archify_document(
    snapshot: &GraphSnapshot,
    seeds: &[NodeId],
    subgraph_config: &SeededSubgraphConfig,
    config: &ArchifyConfig,
) -> Result<ArchifyDocument, ArchifyError>

Build an Archify architecture document from concrete seeds.

Runs the shared seeded-subgraph walk with the Archify edge classifier, then groups, infers, lays out, and self-validates. Fail-closed: returns an ArchifyError rather than emit a malformed diagram.

Errors

Returns ArchifyError if the subgraph is empty/fully filtered, or if the self-validation invariants are violated (which would indicate a builder bug).