Mock Service Worker 3.0 becomes ESM-only and raises runtime baselines

MSW released a major version that changes module, Node.js and TypeScript requirements while adding browser and GraphQL capabilities.

Machine confirmed · generated by codex/gpt-5.6-luna

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Summary

MSW 3.0 is ESM-only, drops supported Node.js versions below 22 and requires TypeScript 5.9 or newer. The release adds a Vite plugin, GraphQL subscriptions, navigation and form interception, WebSocket events and fixes for browser-mode test flakiness.

Why it matters

MSW is widely used for API mocking, so its major runtime and module changes can affect frontend test suites and build pipelines at scale.

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Sources

MSW v3.0.0
MSW v3.0.0 release metadata

Summary

Why it matters

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