Firehose

Anthropic successfully migrated 10 code packages (tens to hundreds of thousands of lines of code) using Claude Code, achieving 100% test suite pass rate and minimal regressions in under two weeks. This was made possible by leveraging AI agents to automate the migration process, rather than manual translation, reducing the project duration from multi-years to weeks. The migration was made feasible by the shift in landscape, where the original trade-offs of the migrated language were no longer justifiable due to the language's growing popularity. AI summary