Setup TS Deep Modules

Setup Ts Deep Modules

Make every package in a TypeScript monorepo a deep module using dependency-cruiser to enforce entry-point boundaries.

The shape this enforces

src/packages/
  <name>/
    index.ts        - an entry point (public)
    client.ts       - another entry point (packages may expose several)
    lib/            - implementation: hidden from outside
    tests/          - co-located tests + fixtures (private)

Four rules (all error level)

1. Entry-point boundary - code outside a package may import only root files
2. Intra-package freedom - a package's own files import each other freely
3. Tests through entry points - test files import entry points only
4. No circular dependencies between packages

Setup

1. Install dependency-cruiser
2. Create the configuration with the four rules
3. Run initial lint to find violations
4. Fix or accept existing violations before enforcement

Common Pitfalls

• Not running the verification after setup: The skill includes a verification step that proves the rules bite. Skipping it means you will not know if the setup worked.
• Existing code that violates the new rules: The initial lint run will likely catch existing violations. Decide whether to fix them before or after enforcing the rules.
• Entry points that export too much: A package's root files are its public API. Barrel files that re-export everything undermine the deep module pattern.

Verification Checklist

• dependency-cruiser installed
• Configuration created with 4 rules
• Initial lint run completed
• Existing violations identified
• Entry point boundaries enforced