Leonardo Estacio developed and integrated a new Vagabond Manga Source within the keiyoushi/extensions-source repository, expanding content access and improving reliability for manga readers. He implemented robust URL handling using Kotlin, including query parameter encoding and dedicated URL constructors, which reduced failures related to malformed links. Leonardo also enhanced code maintainability by removing hardcoded IDs, addressing indentation issues, and updating UI assets such as the launcher icon. In addition, he contributed to the mdn/content repository by standardizing documentation, specifically correcting FTP capitalization for consistency. His work demonstrated depth in API integration, Android development, and technical documentation, focusing on maintainable solutions.