# Understanding the package.json File in Nutlope/hallmark: AI Skill Manifest Explained

> Explore the package.json in Nutlope/hallmark, an AI skill manifest. Learn how it defines metadata and supports LLM harnesses like Claude, Cursor, and Codex.

- Repository: [Hassan El Mghari/hallmark](https://github.com/Nutlope/hallmark)
- Tags: internals
- Published: 2026-07-14

---

**The [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) in Nutlope/hallmark serves as both an npm package manifest and an AI skill configuration file, defining metadata, distribution rules, and supported LLM harnesses including Claude, Cursor, and Codex.**

The [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) file in the [Nutlope/hallmark](https://github.com/Nutlope/hallmark) repository acts as the central manifest for this design skill, extending beyond traditional Node.js package management to describe how AI coding assistants interact with the codebase. It configures the skill's metadata, entry points, and runtime behavior while maintaining standard npm compatibility for distribution. Understanding this file is essential for developers looking to extend the skill or integrate it into custom AI assistant workflows.

## Standard npm Metadata Fields

The Hallmark [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) begins with conventional fields that identify the package within the npm ecosystem.

### Package Identity and Versioning

The `name` field is set to `hallmark`, identifying the skill package for imports and registry references. The `version` field tracks releases (currently `1.1.0`), signaling new capabilities or breaking changes to downstream consumers. These fields work together to ensure proper dependency management when the skill is distributed as a package.

### Discovery and Documentation

The `description` field explains that Hallmark is a *"design skill for AI coding assistants"* powered by Together AI, appearing in npm search results and generated documentation. The `keywords` array contains searchable tags including `claude`, `design`, and `oklch`, optimizing discovery in skill registries and informing assistants about the domains covered. The `license` field declares the MIT license, allowing unrestricted reuse while preserving attribution.

## AI-Specific Configuration

What distinguishes this [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) from standard Node packages is the custom `skill` field that configures the AI runtime environment.

### The Skill Entry Point

The `skill.entry` property points to [`SKILL.md`](https://github.com/Nutlope/hallmark/blob/main/SKILL.md), the markdown file containing the skill's definition, verbs, and flow diagrams. This file serves as the primary instruction set for LLMs interpreting the Hallmark design system.

### Reference Documentation

The `skill.references` directory contains auxiliary markdown files (such as [`structure.md`](https://github.com/Nutlope/hallmark/blob/main/structure.md) and [`custom-theme.md`](https://github.com/Nutlope/hallmark/blob/main/custom-theme.md)) that the skill accesses at runtime. These files provide additional context and constraints that help AI assistants generate accurate design code.

### Supported LLM Harnesses

The `skill.harnesses` array specifies which AI assistants can execute the skill: `claude-code`, `cursor`, and `codex`. This configuration allows the Hallmark runtime to wire the skill into the appropriate LLM environments automatically.

## Distribution and Publishing Configuration

The [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) controls exactly what gets published to npm, keeping the package lightweight and focused.

### Restricting Published Files

The `files` array is set to `["skills"]`, ensuring that only the `skills` directory is included when the package is packed. This excludes development artifacts and source code, publishing only the assets necessary for the skill to function.

```json
{
  "files": ["skills"]
}

```

When running `npm pack`, the resulting tarball contains only the skill definitions and reference documents, minimizing download size for end users.

### ES Module Support

The `type` field is set to `"module"`, enabling ES module syntax throughout the codebase. This modern JavaScript module system is required for the dynamic imports and top-level await patterns used by the skill's entry points.

## Development Workflow

The `scripts` section provides utilities for local development and testing.

### Previewing Documentation

The `serve` script launches a local HTTP server on port **4173** to preview the skill's documentation and UI assets:

```bash
npm run serve

```

This executes `python3 -m http.server --directory site 4173`, serving the static `site` folder that contains generated documentation and examples.

## Reading the Skill Manifest Programmatically

You can inspect the skill configuration at runtime by reading the [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) and accessing the custom `skill` field:

```javascript
import { readFile } from 'fs/promises';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';

const __dirname = dirname(fileURLToPath(import.meta.url));
const pkgPath = join(__dirname, 'package.json');

async function getSkillInfo() {
  const raw = await readFile(pkgPath, 'utf-8');
  const pkg = JSON.parse(raw);
  console.log('Skill name:', pkg.name);
  console.log('Version:', pkg.version);
  console.log('Supported LLMs:', pkg.skill.harnesses.join(', '));
}

getSkillInfo();

```

This outputs the skill metadata and supported harnesses, useful for building tools that dynamically load or validate AI skills.

## Packaging and Publishing

When preparing the package for distribution, npm respects the `files` whitelist:

```bash
npm pack   # Creates hallmark-1.1.0.tgz

tar -tzf hallmark-1.1.0.tgz | grep '^package/skills/'

```

The output confirms that only the skill assets are included:

```

package/skills/hallmark/SKILL.md
package/skills/hallmark/references/

```

This selective packaging ensures that consumers receive only the necessary skill definitions without development dependencies or source code.

## Summary

- The [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) in Nutlope/hallmark functions as a dual-purpose manifest for both npm distribution and AI skill configuration.
- The custom `skill` field defines the entry point ([`SKILL.md`](https://github.com/Nutlope/hallmark/blob/main/SKILL.md)), reference documentation directory, and supported LLM harnesses (Claude, Cursor, Codex).
- The `files` array restricts publishing to the `skills` folder, keeping the package lightweight and focused.
- The `type: "module"` declaration enables modern ES module syntax required by the skill's architecture.
- The `serve` script provides local preview capabilities on port 4173 using Python's built-in HTTP server.

## Frequently Asked Questions

### What is the purpose of the custom "skill" field in package.json?

The `skill` field is a custom configuration block specific to the Hallmark framework that defines how AI assistants interact with the package. It specifies the path to the skill definition (`entry`), the location of auxiliary reference documents (`references`), and which AI coding assistants can execute the skill (`harnesses`). This field is read by the Hallmark runtime to wire the skill into appropriate LLM environments like Claude Code, Cursor, and Codex.

### Which AI assistants are supported by Hallmark?

According to the `skill.harnesses` array in the [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json), Hallmark supports three AI coding assistants: **claude-code**, **cursor**, and **codex**. These entries tell the Hallmark runtime which LLM environments are compatible with the skill's instruction set and reference materials.

### Why does the package only include the "skills" folder when published?

The `files` array in [`package.json`](https://github.com/Nutlope/hallmark/blob/main/package.json) is explicitly set to `["skills"]`, which restricts npm to include only that directory when creating the package tarball. This design choice keeps the published artifact lightweight by excluding development dependencies, source code, and build tools, ensuring that end users receive only the assets necessary for the AI skill to function.

### How do I preview the Hallmark documentation locally?

Run `npm run serve` from the repository root to start a local development server. This command executes `python3 -m http.server --directory site 4173`, which serves the static `site` folder on port 4173. You can then navigate to `http://localhost:4173` to preview the skill's documentation and UI assets before publishing.