Francesc Arpi developed Catalan localization support for the Ghostty repository, focusing on internationalization and translation management using PO files and Zig. He introduced a new translation file, updated the localization configuration, and ensured Catalan was included among supported locales, directly improving accessibility for Catalan-speaking users. Francesc refined translations to address language nuances and adjusted string lengths to fit UI constraints, ensuring accurate rendering of interface elements such as 'Reload Configuration' and 'Deny.' His work demonstrated a methodical approach to localization, emphasizing both linguistic accuracy and technical integration, though the scope was limited to a single feature over a one-month period.