TypeScript has evolved from simple type checking into a powerful static analysis language capable of enforcing enterprise architecture boundaries at compile time.
1. Branded Types for Domain Validation
Avoid passing raw strings or numbers for entity identifiers. Branded types (e.g. UserId, OrderId) guarantee that an ID validated for one domain cannot be accidentally passed to another.
2. Exhaustive Switch Checking with `never`
When handling complex state machines with discriminated unions, assign the default fallthrough branch to a variable of type never. If a new union variant is added in the future, TypeScript will immediately flag an unhandled case at compile time.
3. Zod & Type-Safe Boundary Schemas
Never trust incoming data over network boundaries. Pair Zod schemas with TypeScript inference to automatically validate API request payloads and environment variables.