Worked on the bazelbuild/bazel repository to deliver wildcard support for Bazel toolchain aspects, enabling aspects to interact with multiple toolchains without requiring explicit enumeration. This feature streamlines build configuration for large repositories by allowing rule authors to use a wildcard character, reducing boilerplate and improving build graph flexibility. The implementation involved iterating over toolchain_types within Bazel’s build API and was developed using Java with a focus on build system development. Comprehensive tests were added to cover new wildcard use cases, and the work was linked to a tracked issue and pull request, demonstrating depth in Bazel’s toolchain model.