[Basnederveen]

What

The kernel builds every primitive and boolean result face by face with brep::Builder, but the builder is crate-private. A crate that depends on OpenGeometry and needs a solid the primitives don't cover (for example a part made of planar faces and cylinder sectors, laid out by its own rules) can't build one, except by writing BRep JSON by hand and reading it back with BrepEnvelope::from_json. That path skips the checks the builder does as it goes (an edge used by a third loop, a missing edge) and gives no face ids back.

This makes the builder usable from outside the crate, with the smallest surface that can describe a face:

• brep::Builder: new, vertex, edge, face, face_with_holes, finish_solid, plus two new methods:
  • brep(): read access to the body under construction (e.g. to look up an edge's curve);
  • set_face_sense(face, Orientation): a face whose material normal opposes its surface normal (the inside of a tube), without reaching into the topology.
• face and face_with_holes return the new face's id instead of (), so set_face_sense can use it. The 14 internal call sites that used the call as a tail expression now end in ?; Ok(()).
• brep::{Use, boundary, plane_boundary, uv_line}: the loop edge uses.
• Types those signatures need, made public: brep::Orientation, brep::PcurveGeometry (with IntersectionSide, which one of its variants holds) and math::Interval::new. PcurveGeometry and Orientation are already part of the BRep JSON schema.

edge_geometry, face_loop, finish_wire, WireUse, dimensions and padded_uv_bounds stay crate-private. Nothing changes for the TypeScript API.

Tests

• New tests/public_brep_builder.rs, using only the public API:
  • a 2 x 3 x 4 box built face by face: face ids 0 to 5, finish_solid and validate pass, 12 edges and 24 half-edges, volume 24, a point inside classifies as Inside and one outside as Outside, STEP export writes 6 faces;
  • set_face_sense on the top face's id turns its face_normal_at from +z to -z, and an unknown id is a MissingReference;
  • a face that uses an edge a third time is rejected with InvalidTopology.
• cargo fmt --check and cargo clippy --all-targets -D warnings: clean.
• cargo test --all-targets with CI=true (Windows x86_64, no golden file for this target): 788 pass, 0 fail, 1 ignored (main without this change: 785 pass, 0 fail, the same 1 ignored; the 3 new tests are the difference).
• npm run check:source, check:duplicates, check:cycles: clean. check:api reads the built dist/ and was not run (this change has no TypeScript or WASM surface).

Files

• main/opengeometry/src/brep/builder/{brep_builder,boundary,mod}.rs, src/brep/mod.rs, src/brep/pcurve.rs, src/brep/topology/{mod,orientation}.rs, src/math/interval.rs: visibility, the face id return, brep() and set_face_sense
• 10 files under src/primitives/ and src/operations/modifying/boolean/handlers/cylinder_cylinder/: tail calls of face now return Ok(())
• main/opengeometry/tests/public_brep_builder.rs (new)

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