When spectr-ai started as a single package, everything lived in one directory: the CLI engine, the web frontend, shared types, and configuration. It worked fine until it did not. The engine needed its own publish cycle. The web app had different build tooling. Shared types were copy-pasted between files. It was time for a monorepo. This is the practical guide I wish I had. No theory — just the steps, the config files, and the problems I hit along the way. Why pnpm Workspaces I chose pnpm over npm workspaces or Turborepo for three reasons: strict dependency isolation (packages cannot access undeclared dependencies), disk efficiency through content-addressable storage, and the workspace:* protocol that makes cross-package references explicit. Turborepo is great for build orchestration, but pnpm workspaces handle dependency management better out of the box.…