[notnullorvoid]

> TypeScript has very very few options that affect emit, and effectively everyone has settled on one subset now.

Very confused by this statement. There's lots of options that affect emit. And what do you mean a subset has been settled on? Take any 2 TypeScript projects and I'd wager there's a high chance they have options that emit code differently.

Config aside TS emits .d.ts that is not always backwards compatible with older TS versions. Does jsr support typeVersions for such situations?