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15. Monorepo Tooling Strategy

Status: Accepted Date: 2025-07-06

Context​

The project is a large monorepo containing multiple domains, applications, and libraries. Managing dependencies, running tasks (like building, testing, linting), and ensuring consistent development practices across all these packages is a significant challenge. Without a unified tooling strategy, each package might adopt its own scripts and dependencies, leading to a fragmented, inconsistent, and difficult-to-maintain development environment.

Decision​

We will adopt a unified monorepo tooling strategy based on pnpm for package management and Nx for task orchestration.

  • pnpm: Will be used as the package manager to handle dependencies efficiently. Its content-addressable store saves disk space and speeds up installation in a monorepo context. pnpm workspaces will be used to link local packages together, making cross-package development seamless.

  • Nx: Will be used as the primary task runner and build system. It provides powerful features like task caching, dependency graph analysis, and distributed task execution. All package.json scripts in the root and in individual packages will invoke Nx commands (e.g., nx build <project>), abstracting away the underlying toolchain and ensuring a consistent way to run tasks across the entire repository.

Consequences​

Positive:

  • Consistency: Provides a single, consistent way to manage dependencies and run tasks across the entire monorepo.
  • Performance: Nx's caching capabilities significantly speed up builds and tests by only re-running tasks for code that has changed. pnpm's architecture is optimized for monorepos, reducing installation times and disk space usage.
  • Scalability: This tooling is designed to scale with large codebases and many packages, making it easier to manage the project as it grows.
  • Discoverability: The dependency graph visualization from Nx helps developers understand the relationships and dependencies between different parts of the monorepo.

Negative:

  • Learning Curve: Developers new to the project will need to learn the basics of pnpm workspaces and the Nx task-running ecosystem.
  • Configuration Overhead: Setting up and maintaining the nx.json and project.json files for all packages requires initial and ongoing effort.
  • Toolchain Abstraction: While powerful, the abstraction can sometimes make it harder to debug issues with the underlying tools (e.g., a webpack or tsc problem hidden behind an nx build command).

Mitigation:

  • Documentation: Maintain comprehensive documentation on the monorepo tooling, including common commands, setup instructions, and troubleshooting guides.
  • Automation: Use Nx generators and custom scripts to automate the creation of new packages and the configuration of their project.json files, ensuring consistency.
  • Training: Provide "getting started" guides and training sessions for new developers to quickly get them up to speed with the tooling.