linting type-inference typescript biome migration

Biome v2 adds type inference without TypeScript

Type-aware linting rules now work without the TypeScript compiler installed, using Biome's own type inference engine with 75% detection parity on floating promises at lower performance cost.

Summary

Eliminates TypeScript as a hard dependency for type-checking lints, reducing install size and CI overhead. Multi-file analysis unlocks rules that require cross-module context, previously impossible in v1.

Why it matters

Implementation verdict

Replaces typescript-eslint for type-aware rules if detection rates reach production confidence; requires migration via `biome migrate --write` command and review of breaking config changes. Opt-in file scanner means existing v1 setups won't slow down. Worth adopting now for formatting/linting speed gains; type-inference rules still maturing (75% recall is preliminary).

Sources

1.the first JavaScript and TypeScript linter that provides type-aware linting rules that doesn't rely on the TypeScript compiler
2.our noFloatingPromises rule, which is based on our new type inference work, can detect floating promises in about 75% of the cases that would be detected by using typescript-eslint, at a fraction of the performance impact
3.It's opt-in; which means migrating from v1 to v2 won't significantly affect the performance of formatting and linting your projects
4.A full scan (which scans all your project files and node_modules) is performed only when project rules are enabled

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