September 2021: Stabilized Bundler Gemfile handling across initialization paths in ruby/ruby and rubygems/rubygems. Fixed inconsistencies where Gemfile settings were honored for bundle exec but not for Bundler.setup or bundler/setup, delivering consistent Gemfile-driven behavior and more reliable gem resolution. Delivered commit b43844c7ba3e4911812c8ac400decac0e0722bc7 for ruby/ruby and commit 5e6333108b5beaed8f02160592238ce2d1f1d5ba for rubygems/rubygems. Business value: reduces environment-specific surprises in CI/builds, lowers support overhead, and enhances developer experience by ensuring Gemfile settings are consistently respected across initialization paths. Technologies/skills demonstrated: Ruby, Bundler, Gemfile resolution, Bundler.setup, cross-repo coordination, code hygiene and regression risk mitigation.