Pattern: Vibe Porting Becomes a Validated Production Technique — Test Suites Are the Enabler

Simon Willison / Reco.ai·high signal

Three independent case studies in March 2026 validate 'vibe porting' — using AI to rewrite codebases across languages — as production-ready when paired with existing test suites and shadow deployments. Reco.ai's JSONata→Go rewrite ($500K/year saved, 7 hours), Cloudflare's vinext rewrite, and Simon Willison's datasette plugin rewrites all follow the same pattern: port the test suite first, implement until green, shadow-deploy, promote on zero mismatches. The prerequisite is clear: comprehensive test coverage. Without it, vibe porting is gambling. With it, it's the fastest way to eliminate legacy language dependencies.