@howells/boundaries

Opinionated boundary conventions for JavaScript and TypeScript workspaces.

The executable is boundaries.

Install

pnpm add -D @howells/boundaries

Use

Try without installing:

npx @howells/boundaries
npx @howells/boundaries init --dry-run
npx @howells/boundaries check --profile feature-sliced
npx @howells/boundaries --help

Initialize boundary config:

pnpm exec boundaries init

This adds:

• root turbo.json boundary rules
• package-level turbo.json tags
• a root package.json script: "boundaries": "boundaries check"

Run checks:

pnpm boundaries

or:

pnpm exec boundaries check

Check a common JavaScript source architecture without requiring Turbo:

pnpm exec boundaries check --profile feature-sliced
pnpm exec boundaries check --profile next-feature
pnpm exec boundaries check --profile clean-node

Explain a relationship:

pnpm exec boundaries explain apps/web packages/ui
pnpm exec boundaries explain apps/web apps/admin

Machine-readable output:

pnpm exec boundaries --schema
pnpm exec boundaries init --dry-run --json
pnpm exec boundaries check --profile feature-sliced --json
pnpm exec boundaries explain apps/web packages/ui --json

Default Policy

The default tags are:

type:app
type:package
type:tooling
scope:<workspace-name>
visibility:public
visibility:internal

The default rules are:

type:app      cannot depend on type:app
type:package  cannot depend on type:app
type:tooling  cannot depend on type:app

This blocks app-to-app imports and keeps shared packages from reaching into deployable apps.

visibility:* tags are generated as metadata, but no default rule is attached to them yet. Public packages often depend on private dev tooling packages, so runtime visibility policy needs a more precise model.

Backend

boundaries check validates the generated convention layer, then delegates to:

turbo boundaries

Use this in Turborepo repos that already have turbo installed.

boundaries check --profile <name> uses the built-in JavaScript import scanner instead of Turbo. It supports relative imports plus common root aliases such as @/, ~/, and src/.

JavaScript Profiles

Profiles enforce layer direction over src/ imports:

feature-sliced: app -> pages -> widgets -> features -> entities -> shared
next-feature:   app/pages -> components -> features -> entities -> lib/shared
clean-node:     adapters/infrastructure -> application -> domain

Higher layers may import lower layers. Lower layers may not import higher layers.