priority: critical

TypeScript Strictest Standards

TypeScript 5.x · Strictest typing · No any/object · Generics required · Tests next to source

• Enable ALL strict flags: strict, noUncheckedIndexedAccess, exactOptionalPropertyTypes
• Ban any and object types; use unknown with guards, Record<string, unknown>
• Generics with constraints: <T extends BaseType>, satisfies operator, const assertions
• Tests: .spec.ts next to source files (NOT tests/); vitest, 80%+ coverage
• Functional: pure functions over classes, map/filter/reduce, immutability, readonly
• Nullish coalescing ??, optional chaining ?., type predicates (x is Type)
• Import type for types, organize by feature, path aliases (@/lib/*)
• Biome for linting/formatting, pnpm ≥10.17, pnpm-lock.yaml committed
• React: function components, custom hooks (use*), proper prop typing
• Never: any/object types, test dirs, non-null assertions !, || for defaults