Function export_debug_obj 

pub fn export_debug_obj(
    mesh: &Mesh,
    result: &RecognitionResult,
) -> Result<DebugObjExport, RecognitionError>

Export an input mesh and recognition result as Wavefront OBJ/MTL text.

Region colors are deterministic and intended only for debugging. OBJ groups retain primitive type and region number; unresolved triangles are gray and triangles absent from the result are black. Invalid indices or overlapping result partitions are rejected rather than producing misleading geometry.