DOP Programming organizes programs around Domains, Objects, Processes, and conceptual ownership. Its current expression is a source layout convention that keeps the program's important concepts visible in the filesystem.

The aim is to help people understand a program as its implementation grows, including when AI writes much of the code. A reader should be able to find the program's conceptual areas, important stateful concepts, and significant activities through its source structure.

Install the setup skill:

npx skills add hyfdev/domain-object-process-programming --skill dop-setup -g

In your project, ask your agent to use dop-setup. The skill installs the complete DOP rules into the root AGENTS.md, or an existing CLAUDE.md when the project uses that instead. It preserves other instructions and project-specific additions. In a monorepo, run setup once at the workspace root; each package or crate follows DOP within its own source structure.

Agents follow the installed rules during development. Setup changes instructions only; reorganizing an existing codebase is a separate task. To update the rules, update the skill and run dop-setup in the project again:

npx skills update dop-setup -g

For manual setup, copy the complete raw DOP rule block, including its markers, into your project's AGENTS.md. Keep project-specific decisions outside <!-- DOP:START --> and <!-- DOP:END -->.

Each package or crate represents a root Domain. Within a Domain, objects/, processes/, and domains/ contain its Objects, Processes, and Subdomains. Apply the same convention recursively within Subdomains, creating directories as needed.

For example, Cart.add_item() belongs to Cart because it updates the cart while maintaining its rules. PlaceOrder is a Process that coordinates the work of placing an order. A helper used only to implement that process stays inside it. DOP.md contains the definitions and placement rules.

This example shows an online store package. Checkout owns the concepts involved in placing an order. The filenames use TypeScript conventions.

<package-source-root>/
├── index.ts
├── objects/
│   ├── customer.ts
│   └── product.ts
├── domains/
│   └── checkout/
│       ├── objects/
│       │   ├── cart.ts
│       │   └── orders/
│       │       ├── order.ts
│       │       └── order_item.ts
│       └── processes/
│           └── place_order/
│               ├── index.ts
│               ├── calculate_total.ts
│               └── validate_items.ts
└── fixtures/

• domains/checkout/ declares a Subdomain with its own vocabulary: Cart, Order, OrderItem, and PlaceOrder.
• Within Checkout, objects/orders/ groups Order and OrderItem. It does not introduce a Subdomain.
• processes/place_order/ implements one Process. Calculating the total and validating items are internal steps in this example.
• The package's index.ts and fixtures/ follow ordinary source organization and have no automatic DOP role.

MIT — Copyright (c) 2026 Yunfei He.