tilsotua calculates the world-coordinate system (WCS) positions of slits in multislit mask designs used for the Low-Resolution Imaging Spectrograph (LRIS). The package ingests slit coordinate information stored in FITS files from mask design archives or autoslit outputs and reconstructs the corresponding slit positions in sky coordinates. It applies optional astrometric corrections by comparing alignment star slit locations to modern catalogs to refine the slit WCS positions. tilsotua outputs updated FITS files with filled slit center coordinates, CSV tables of slit corner and center positions, DS9 region files for visualization, and quick-look plots of mask geometries. The software supports reusable Python interfaces and command-line workflows for processing observational mask data.