In January 2026, Theo Sib worked on stabilizing core geometry operations in the FreeCAD/FreeCAD repository, focusing on resolving a regression in the mirror() function for shapes with non-identity Placement. Using C++ and Python, Theo identified and fixed the bug that caused mirrored geometry to behave inconsistently when shapes were oriented, restoring expected symmetry for users. He reinforced the solution by expanding unit tests and introducing a dedicated regression test, ensuring future reliability of mirrored transformations. Theo’s work demonstrated depth in 3D modeling and geometry processing, directly improving the accuracy and robustness of FreeCAD’s modeling workflows for oriented shapes.