Archive export writes non-standard relationship payloads

[jillesvangurp]

Summary

Archive export emits relationship features in a non-standard custom format (contains, numeric direction, references[]) instead of IMDF relationship properties.

Evidence

• src/lib/imdf/archiveExport.ts:602-616 generates relationship features with:
  • category: "contains"
  • direction: 1
  • references: [{id, feature_type}, ...]
• src/lib/imdf/archiveExport.ts:606 forces relationship geometry to null.

Why this is a bug

This does not match IMDF relationship property structure (origin, optional intermediary, destination, string direction enum). Exported archives may fail downstream validation or lose interoperability with IMDF tooling.

Reference: https://docs.ogc.org/cs/20-094/relationship/index.html

Reproduction

1. Export a building archive with features that produce containment relationships.
2. Inspect relationship.geojson.
3. Observe custom references[] + numeric direction payload instead of IMDF relationship fields.

Expected

Export relationships in IMDF-compliant structure so archives are portable across IMDF consumers.

Impact

Generated datasets are not fully interoperable and can be rejected by standards-based importers.