It covers the 2026 arbitrage between the two — new projects default to Biome for a fast zero-config start, established/typed-heavy codebases lean ESLint + typescript-eslint — plus a note on Oxlint as a challenger, and the rule to never run Biome and Prettier on the same files.

Out of scope: type checking itself (tsc --noEmit, tsconfig flags) belongs to ts-config; test-runner configuration belongs to ts-testing.

TypeScript Linting & Formatting

Agent Workflow (MANDATORY)