Felix contributed to core infrastructure in both the ziglang/zig and gleam-lang/stdlib repositories, focusing on package management and string manipulation. In Zig, Felix enhanced dependency fetching by updating zig fetch to treat .jar files as .zip archives, improving Java artifact handling and reducing unpacking errors in cross-language builds. In Gleam, Felix implemented unified string prefix and suffix utilities, adding trim_prefix, trim_suffix, strip_prefix, and strip_suffix functions with comprehensive tests. This work improved API safety and reduced boilerplate for common parsing tasks. Felix’s contributions demonstrated depth in functional programming, system programming, and testing using Erlang, Gleam, and Zig.