Anthropic Dynamic Workflows Used to Port Bun from Zig to Rust with Agent Swarm

Anthropic·high signal

Anthropic's dynamic workflows let Claude Code write its own JavaScript orchestration script and fan work across tens to hundreds of background subagents, with agents attacking a problem from independent angles while others try to refute findings until answers converge. In a flagship demonstration, Jarred Sumner used it to port Bun from Zig to Rust — ~750,000 lines, 99.8% of the existing test suite passing, eleven days from first commit to merge — with one workflow mapping Rust lifetimes per struct field and the next emitting behavior-identical .rs files in parallel. It is the clearest evidence yet that large-scale code migration can be parallelized across an agent fleet.