Port upstream CDT changes to C# (870c07c) — 2026-09-21

[github-actions]

Upstream Sync Task

@Copilot please port the upstream changes listed below to C# and open a pull request.

New commits have been pushed to artem-ogre/CDT since the last sync.

Previous synced commit: 9f474cb
New upstream commit: 870c07c
Full diff: artem-ogre/CDT@9f474cb...870c07c

Upstream commits to port

• 870c07c Nano-addition
• c888b30 Ruppert (Delaunay) refinement: rebase, fix crashes/non-termination, add tests (#225)

What to port

Please port all upstream C++ changes to C# and open a pull request.

Key files to check in the upstream diff:

• CDT/include/CDT.h and CDT/include/CDT.hpp → port any algorithm changes to src/CDT.Core/
• CDT/include/Predicates.h → port to src/CDT.Core/Predicates.cs
• CDT/include/KDTree.h → port to src/CDT.Core/KdTree.cs
• Any new types or utilities → port to src/CDT.Core/Types.cs or new files as appropriate

After porting:

1. Run dotnet test and ensure all tests pass
2. Update test inputs/expected outputs if needed