setup-ts-deep-modules Skill for Claude: Enforce Package Boundaries

setup-ts-deep-modules wires dependency-cruiser into a TypeScript repo so each package can only be used through its entry-point files.

Installs: 392.5K; on skills.sh
Stars: 309.2K; on GitHub
Files: 2; besides SKILL.md
Updated: Nov 2026; last repo commit

setup-ts-deep-modules is a skill you invoke yourself. It installs dependency-cruiser, copies a config with four rules, adds a lint:boundaries script, creates an example package, and then proves the rules work by adding a bad import, watching the check fail and removing it. The rules: outsiders import only a package's root files, packages import their own internals freely, tests go through entry points, and no dependency cycles.

It is in the in-progress folder of the mattpocock/skills repo, which the repo calls beta. It uses the codebase-design skill for vocabulary, so install both. It edits package.json, adds files and updates CLAUDE.md or AGENTS.md.

Good for

TypeScript developers who want enforced package boundaries in a monorepo
Teams whose AI agents keep importing internal files
Maintainers who want a copy-me example package and README

Install setup-ts-deep-modules

Claude Code

Copy this prompt.

Install the setup-ts-deep-modules skill in Claude Code. Run this command:

npx skills@latest add mattpocock/skills --skill=setup-ts-deep-modules --skill=codebase-design

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

The repo's in-progress README says these skills are left out of the plugin and installed one by one with --skill. codebase-design is the vocabulary skill that SKILL.md tells Claude to call.

From the project README. Source.

What's in the skill

When it loads

Wire dependency-cruiser into a TypeScript repo so each package is a deep module, with implementation hidden in subfolders and reachable only through its entry-point files. User-invoked.

Sections in SKILL.md

The shape this enforces
Steps
1. Detect the environment
2. Install dependency-cruiser
3. Write the config
4. Wire it into the checks
5. Scaffold the example package
6. Prove the rules bite
7. Document the convention
Notes

Key facts

Author: mattpocock (mattpocock/skills repo owner)
License: MIT
Installs on skills.sh: 392,521 as of 2026-11-02
GitHub stars: 309,237 for the whole mattpocock/skills repo
skills.sh audits: Gen Agent Trust Hub pass, Socket pass, Snyk pass
What is inside: 3 files: SKILL.md, dependency-cruiser.config.cjs and agents/openai.yaml
Needs: A TypeScript repo, a package manager (pnpm, yarn, bun or npm), and the codebase-design skill for the vocabulary it calls
Last commit to the repo: 2026-11-01

What it includes

Finds package manager, packages root, existing config
Uses lockfiles to pick pnpm, yarn, bun or npm and src/packages or packages. An existing .dependency-cruiser file is merged into, not overwritten.
Try: “/setup-ts-deep-modules”
Files · 1. Detect the environment
Adds it as a devDependency
Runs your package manager's install command.
Runs code · 2. Install dependency-cruiser
Copies dependency-cruiser.config.cjs to .dependency-cruiser.cjs
Sets PACKAGES_ROOT. Four rules, all errors: entry-point boundary, intra-package freedom, tests through entry points, no cycles.
Write · 3. Write the config
Adds a lint:boundaries script
Runs depcruise on the packages root and folds it into your typecheck or CI script when one exists.
Write · 4. Wire it into checks
Creates <packages-root>/example/
An index.ts entry point, a hidden lib/impl.ts and a test that imports only the entry point.
Write · 5. Scaffold an example package
Pass, then fail on a deep import, then pass
Temporarily adds a deep import to the example test and expects a tests-through-entrypoints failure, then reverts it.
Runs code · 6. Prove the rules bite
Writes a packages README and an agent pointer
Adds <packages-root>/README.md that discourages barrel files, and one line in CLAUDE.md or AGENTS.md linking to it.
Write · 7. Document the convention

From the official docs

Permissions

Medium risk

It installs a package and edits several files in your repo, including a temporary change to a test. Run it on a clean branch and review the diff.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It installs a package and edits project files
Commit or stash first. It changes package.json, adds config and an example package, and edits CLAUDE.md or AGENTS.md.
It briefly breaks a test on purpose
Step 6 adds a deep import to prove the check fails, then reverts it. If a run stops halfway, remove the import from the example test.

Technical details

Talks to	Package registry through your package manager's install
Scopes	Installs a dev dependency with your package manager Writes .dependency-cruiser.cjs, an example package, a README and package.json scripts Edits CLAUDE.md or AGENTS.md; temporarily edits a test to prove the rule fails

Questions

What does setup-ts-deep-modules do?

It sets up dependency-cruiser in a TypeScript repo so each package is a deep module: a small public surface of root files and hidden implementation in subfolders. It then checks the rules actually fail on a violation.

How do I install it?

Use the install box at the top of this page. Install it with codebase-design, which it calls for vocabulary. The repo says the in-progress skills are not in its plugin and must be installed one by one.

How do I run it?

SKILL.md says it is user-invoked, with the model's own invocation turned off. Type /setup-ts-deep-modules in a TypeScript repo.

Will it change my project files?

Yes. It adds dependency-cruiser to devDependencies, writes .dependency-cruiser.cjs, edits package.json scripts, creates an example package and README, and adds a line to CLAUDE.md or AGENTS.md. Commit first so you can review the diff.

Does it overwrite an existing dependency-cruiser config?

No. SKILL.md says to merge its four rules and options into an existing config and tell you what was added.

Is it stable?

The repo's in-progress README calls these skills beta: they can change or disappear without warning, and they are left out of the plugin and top-level README.

Is setup-ts-deep-modules safe?

It installs a package and edits your repo, so run it on a clean branch. On skills.sh the audits read Gen Agent Trust Hub pass, Socket pass and Snyk pass.

Information

updated Nov 2, 2026

Repository: mattpocock/skills
Folder: skills/in-progress/setup-ts-deep-modules

mattpocock/skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 4

mattpocock/skills in-progress README · github.com
setup-ts-deep-modules SKILL.md · github.com
mattpocock/skills in-progress README · github.com
skills.sh listing and audits · skills.sh