Codebase Architecture Decide a TypeScript codebase's structure, improve it where change has become expensive, and make it hold. The target is a codebase a reader can hold in their head: few surfaces, one canonical way to do each job, and behaviour where you would first look for it. - IS: folder structures, module interfaces, request context and middleware pipelines, frontend/backend boundaries; architecture briefs; domain language and decision records; domain-informed deepening; guardrail tooling, CI gates, and agent wayfinding. - IS NOT: scaffolding a new repo ( for a Next.js turborepo, for…