> ## 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 Product Edit domain links to other modules across the marketplace.

Modules in Mercur never reference each other directly. They connect through
**module links**. Once a link is defined, you retrieve related records with
`query.graph` using the link alias.

## Product

The Product Edit domain links to the Product module so a product's change
history hangs off the product itself.

| Linked module | Relationship                                                                                       |
| ------------- | -------------------------------------------------------------------------------------------------- |
| **Product**   | A product has many changes (`product_change.product_id`, read-only). Exposed as `product.changes`. |

```ts theme={null}
const { data: products } = await query.graph({
  entity: "product",
  fields: ["id", "title", "changes.status", "changes.actions.action"],
})
```

<Note>
  The link is **read-only** and has no pivot table. The FK lives directly on the
  `product_change` row. It exists so you read the audit trail through
  `product.changes`. You can't write a change through the link itself. Stage
  changes with the [workflows](/platform/product-edit/reference/workflows).
</Note>

## Actor references

The `created_by`, `confirmed_by`, `declined_by`, and `canceled_by` fields hold
actor ids (the dashboard user who staged or resolved the change). They are plain
text references for the audit trail, not module links, so they aren't resolved
through `query.graph`.