modfence

TypeScript import-boundary linter. Declare layers, say which layers may import which, and fail CI when someone reaches across the fence.

Install

npm install -g @magnexis/modfence
npx @magnexis/modfence --help

Requires Node.js 20+.

Why

eslint-plugin-import can ban paths, but teams usually want a layer story: UI may talk to domain, domain must not talk to infra, infra may implement domain. Cycles still sneak in. modfence is a dedicated CLI for that policy — including why (explain a file) and graph (Mermaid of observed layer edges).

Quick start

npx @magnexis/modfence init
npx @magnexis/modfence check

modfence.json:

{
  "root": ".",
  "forbidCycles": true,
  "layers": [
    { "name": "ui", "glob": "src/ui/**" },
    { "name": "domain", "glob": "src/domain/**" },
    { "name": "infra", "glob": "src/infra/**" }
  ],
  "allow": [
    { "from": "ui", "to": ["domain"] },
    { "from": "domain", "to": [] },
    { "from": "infra", "to": ["domain"] }
  ]
}

Same-layer imports are always allowed. External packages (react, node:fs) are ignored.

CLI

modfence init              Write starter modfence.json
modfence check [--json]    Exit 1 on layer or cycle violations
modfence why <file>        Layer + outbound relative imports
modfence graph             Mermaid flowchart of layer → layer edges

CI:

- run: npx @magnexis/modfence check --json

Library

import { checkLayers, collectEdges, defaultConfig } from "@magnexis/modfence";

const config = defaultConfig();
const edges = await collectEdges({ ...config, root: process.cwd() });
const violations = checkLayers(config, edges);

Development

git clone https://github.com/theworker02/modfence.git
cd modfence
npm install
npm test
npm run build

License

MIT. Sponsor via GitHub or thanks.dev.