> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mercurjs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Links to other modules

> How the Commission domain connects to the catalog, sellers, and orders.

Most Mercur modules connect to each other through **module links** (`defineLink`)
resolved with `query.graph`. The Commission module is deliberately different: it
defines **no** module links. Instead it connects to the rest of the marketplace
through **soft references**. These are plain id fields resolved at calculation
time. This keeps commission configuration independent of the catalog and order
modules it scopes against.

## Rules → catalog & sellers

A `CommissionRule` points at a record in another domain through its
`reference` / `reference_id` pair, resolved against the order line's product when
commission is calculated:

| `reference`          | Points at        | Resolved from                  |
| -------------------- | ---------------- | ------------------------------ |
| `product`            | A master product | `item.product.id`              |
| `product_type`       | A product type   | `item.product.type_id`         |
| `product_collection` | A collection     | `item.product.collection_id`   |
| `product_category`   | A category       | `item.product.categories[].id` |
| `seller`             | A store          | `item.offer.seller_id`         |

<Note>
  Products are the shared master catalog, not seller-owned. The `seller`
  dimension resolves through the **offer** on the order line, which carries the
  selling store.
</Note>

## Lines → orders

A `CommissionLine` records which order line it commissions through its
`item_id` (an order line item) or `shipping_method_id` (a shipping method).
These are stored as plain ids, so the payout pipeline reads an order's lines by
querying the commission module directly rather than traversing a link.

<Tip>
  Because these are soft references, deleting a product, category, or order does
  not cascade to commission records. Rules and lines simply stop matching or are
  refreshed on the next order change.
</Tip>