v2.1.0

Archival release accompanying the DOI citation for chapter 4 of the PhD
thesis. Restores correct geometric connection detection (regressed by the
2.0.0 clash-detection refactor), makes the evaluation suite deterministically
reproducible, and completes packaging/citation metadata.

Added

• BuildingInformationModel.trace_connections(start, category, max_depth) —
  breadth-first traversal of the interaction graph from a starting element,
  filtered by relationship category or group, returning the reachable
  elements. Useful for tracing connectivity networks such as MEP flow
  systems or chains of structurally connected members.
• BuildingInformationModel.save now accepts schema and
  tessellation_tolerance arguments for future cross-schema export. Passing
  a schema different from the model's current schema currently raises
  NotImplementedError; saving in the current schema is unchanged.
• CITATION.cff — citation metadata for the archival (DOI) release.
• requirements-freeze.txt — exact dependency versions pinning the
  reference environment used to produce the chapter 4 evaluation results.
• COMPAS_IFC_GEOM_WORKERS environment variable to control the number of
  workers used by the geometry iterator in IFCFile.load_geometries. Set it
  to 1 for deterministic, reproducible geometry evaluation. The chapter 4
  evaluation suite (thesis/appendix/A/run_all.py) now pins this to 1.

Fixed

• Geometric connection detection (compute_connections) now reproduces the
  designed contact counts again. The 2.0.0 refactor that routed clash
  detection through cached world-coord meshes for speed had regressed it;
  several independent defects are addressed:
  • GenericElement.compute_contacts now uses exact B-Rep face-to-face
    contact detection (brep_brep_contacts) when both elements expose B-Rep
    geometry, falling back to the mesh approximation otherwise. The
    mesh-only path could not resolve coplanar "just-touching" faces (e.g.
    beams meeting end-to-end).
  • GenericElement.compute_aabb / compute_obb now honour the inflate
    scaling factor. It was previously ignored, so the compas_model BVH
    broadphase (which inflates AABBs to catch touching neighbours) missed
    element pairs that only touch.
  • IFCFile.load_geometries now fills in the definition-holder products of
    instanced geometry (IfcRepresentationMap / IfcMappedItem), which the
    ifcopenshell geometry iterator does not yield. Previously the shared
    definition holder of every instanced group received no visual_geometry.
  • compute_connections / compute_collisions load tessellated geometry
    for freshly created (not-yet-saved) elements before contact detection,
    so a model built in-memory yields correct contacts without a save/reload.
• GenericElement._world_triangles now falls back to the parametric
  geometry when the tessellated visual_geometry is unavailable, so aabb
  no longer returns None for such elements (which crashed the BVH).
• thesis/appendix/A/run_all.py now reports a crashed evaluation stage as
  an explicit error in the summary instead of silently recording it as
  0 PASS / 0 FAIL.
• thesis/appendix/A/integrated_workflow_test.py now asserts the exact
  designed connection breakdown (6 slab-slab, 18 slab-beam, 8 beam-beam = 32)
  and its preservation through reload and granular export, rather than a loose
  lower-bound check that had masked the connection-detection regression.

Changed

• requirements.txt now declares the previously-undeclared runtime
  dependencies shapely (used by contact/collision detection) and numpy.
• README: corrected the geometry-kernel description — contact/collision
  detection uses a NumPy + Shapely pipeline; CGAL is not currently a
  dependency.