PyIRD: A Python-Based Data Reduction Pipeline for Subaru/IRD and REACH

PyIRD is an open-source Python pipeline for reducing high-dispersion spectroscopic data obtained with the IRD and REACH instruments on the Subaru Telescope. It processes raw detector images into calibrated one-dimensional spectra through a semi-automatic workflow, including readout noise subtraction, flat fielding, aperture extraction, wavelength calibration, and normalization. The design avoids dependencies on legacy tools such as IRAF, enabling reproducible and efficient data reduction for astronomical research. This release corresponds to a stable version of PyIRD intended for use in research workflows in stellar and exoplanet spectroscopy. This version reflects revisions and improvements made during the peer-review process for the Journal of Open Source Software (JOSS) and corresponds to the version submitted for publication.