**Setting Default Price Category on Supplier:**

#. Open a **Supplier** form (res.partner with "Supplier" checkbox enabled)
#. Go to **Purchases** tab
#. In **Price Category Settings** section, select **Default Price Category**
#. Save

**Bulk Update Products:**

#. After setting default price category on supplier
#. Click **"Apply to All Products"** button
#. Confirmation wizard opens showing:

   * Supplier name
   * Price category to apply
   * Count of products to be updated

#. Click **"Confirm"** to execute bulk update
#. Success notification shows number of products updated

**Behavior:**

* Updates all products where ``main_seller_id`` (or ``default_supplier_id``) equals the supplier
* Updates products' ``price_category_id`` field
* **Warning:** This OVERWRITES any existing price category on the products

**Use Cases:**

* Set default price categories for new suppliers
* Bulk reclassify products when changing supplier pricing strategy
* Maintain consistency between supplier and product pricing categories
