How one developer manages a 40-package monorepo with Turborepo, Bun, and Biome

A solo developer built and maintains flare-engine, a modular 2D engine for React Native and Web spanning 40 packages, using a toolchain of Turborepo, Bun, and Biome. The core principle is strict configuration discipline: exactly one root-level config file governs all packages, eliminating per-package ESLint or build configs entirely. Bun serves triple duty as the package manager, test runner, and runtime, while Biome handles linting and formatting across the entire repo in a single pass. Turborepo orchestrates build, test, lint, and typecheck tasks through a shared turbo.json, with Changesets managing versioning and releases. A custom CI script enforces dependency boundaries, failing the build immediately if any package imports from a tier it should not access.