We migrated Calm’s large Rush.js monorepo away from tsc emit and onto Node’s new type stripping feature. Key lessons:

ESM migration was a prerequisite (imports, JSON, CJS compat).

Biggest blocker: thousands of Sinon stubs (solution: “stub classes, not modules”).

Some CJS → ESM package refactors needed (lodash → lodash-es).

Results: local dev tasks ~30–40% faster, CI jobs ~3–6 minutes faster.

Full write-up: https://www.calm.com/blog/engineering/how-we-migrated-our-ru...

Curious if others have tried type stripping in Node 22/23 yet.