codebase-architecture

Designs, deepens, and hardens TypeScript codebase architecture in three modes: folder structures, module contracts, and middleware pipelines for a new app; domain-informed deepening of existing code; and the guardrail tooling, CI gates, and wayfinding that stop a structure decaying. Use when setting up project structure, organizing a monorepo, designing backend modules, writing an architecture brief, recovering domain terminology, recording an architecture decision, or asking "how should I structure this app", "find architecture improvements", "this module is a mess", "make this codebase agent-friendly", "set up guardrails for coding agents", "add a dead-code check", or "my agent can't find anything in this repo". For scaffolding a new repo use scaffold-nextjs or scaffold-cli, for multi-tenant isolation use multi-tenant-architecture, for the AGENTS.md file's own content use agents-md, and for review of a local diff use pr-reviewer.