TypeScript 5.8: Deep dive into immutable module types and conditional inference

The new compiler flags in TS 5.8 substantially reduce type-checking overhead in large monorepos with hundreds of schema types.

Key advantages:

• 30% faster cold type-check times on Zod / Drizzle schema layers.
• Exact constraint propagation without redundant 'as const' assertions.

Here is a simple benchmark comparing type instantiation depths on large OpenAPI specifications.