How to Ship a Major Version People Actually Upgrade To

Shipping a major version of a widely used library is less about the code changes and more about managing uncertainty for downstream teams. The monday.com team shares lessons from releasing Vibe 3, their design system used across hundreds of microfrontends. Key insights: breaking changes accumulate when you follow semver strictly, so majors must be treated as migration systems rather than version bumps. They used early deprecation warnings, codemods for mechanical changes (reducing migration from days to minutes), and an MCP-backed AI assistant to handle ambiguous cases where intent matters. The result was a migration process teams found easier than expected, and infrastructure that made Vibe 4 significantly cheaper to ship.