**Steps to reproduce:**
- Install the `l10n_de` module and switch to a `DE Company`.
- Enable `Peppol` in the Invoicing app settings.
- Open the `DE Company` customer record.
- In the `Invoicing` tab, change the Peppol ID code from `Germany VAT` 
  to `Germany Leitweg-ID` and set a code (e.g., `13075957-K000-52`).
- In the `Contacts & Addresses` tab, create an invoice-type contact named `test`.
- Create a new invoice using the `test` contact.
- Send the invoice via Peppol.
- Download the generated `XML` and inspect the `BuyerReference` field.

**Observation:**
The `<cbc:BuyerReference>` field is set to `N/A` instead of the configured `Leitweg-ID`.

**Root Cause:**
At [1], the `BuyerReference` node is populated using `vals['customer']`. 
For invoices addressed to an invoice-type contact, the contact itself 
does not contain the Peppol configuration, which is stored on the 
commercial partner. As a result, the code fails to retrieve the 
customer's `Leitweg-ID` and leaves the `BuyerReference` field empty.

**Fix:**
This commit ensures that the configured Leitweg-ID is correctly added to the 
`BuyerReference` field for child contact.

[1]:
https://github.com/odoo/odoo/blob/281658e86971687656f3235ac1ff8afcb52f2908/addons/account_edi_ubl_cii/models/account_edi_xml_ubl_xrechnung.py#L87-L97

opw-6269478

Forward-Port-Of: odoo/odoo#269818

## The Problem
When grouping messages, the code was accumulating recordsets using the `|=` union operator inside a loop. Since each union call internally builds an `OrderedSet` over all previously accumulated IDs, the performance degraded quadratically relative to the number of document records. This caused bottlenecks on databases with large message volumes.

## The Solution
* Replaced the `|=` recordset accumulation with a plain Python dictionary of ordered sets to store IDs per operation, while keeping same behavior.
* Deferred the `browse()` call until after the loop is complete.
* Reduced the overall complexity from **$O(N^2)$** to **$O(N)$**.

---

## Benchmarks
*Tested on a customer database grouping by "Created By" and "Created On":*

| Record Count | Before | After | Improvement |
| :--- | :--- | :--- | :--- |
| **300k records** | 83.00s | **1.00s** | **-99%** |
| **30k records** | 0.60s | 0.25s | (Minor) |

**Note:** The performance gains become exponentially more significant as the record count grows.

**OPW-6123758**

Forward-Port-Of: odoo/odoo#269123
Forward-Port-Of: odoo/odoo#260147

## Steps to reproduce

- Create an attribute A, of type always, with 2 values, one should have an extra price
- Create an attribute B, of type never, with 2 values
- Create a product that has both those attributes
- Create a combo with that product with both values for A
- Go to the PoS and order that combo with the value that has an extra price for A
- The extra price is added

## Why the fix:

For variants of type always, a product is created, meaning we can chose which products of this variants to have in our combo.

As we can chose this, it means that we can and should chose the extra price on the combo creation page, not on the attribute page.

It does not make sense to take the attribute extra price into account, as we do not take the unit price of combo items into account, so this extra price should be set on the combo page and we should ignore the attribute's extra price if the type is "always".

The variants are then considered as different products, as they should in this case.

If the type of the attribute is never, we can't chose which one gets an extra price on the combo page, so we should still take the attribute's extra price in this situation, as we have no other way to set it.

We need to have both an always and a never attribute in order to reproduce this bug because if we only have "always" values, the configuration of the combo item is bypassed and is undefined, so **attribute_value_ids** will be undefined in this code and we won't get any value for the extra price in this code: https://github.com/odoo/odoo/blob/c09e8b2fc24ee75495fc947924e29cf5c601506f/addons/point_of_sale/static/src/app/models/utils/compute_combo_items.js#L44-L49 

We now ignore the attribute's extra price if it's type is always, otherwise, it the behavior stays the same.

opw-6262431

Behavior before:
Adjusting physical inventory quantities for reserved packages takes time when linked to large delivery orders (e.g., 400+ lines). The user interface freezes, causing a poor warehouse user experience during stock counts.

Behavior after:
Inventory adjustments on reserved packages process faster. The UI remains responsive, and package records are updated instantly without performance degradation.

Root Cause:
When an inventory adjustment triggers '_free_reservation', it processes move lines sequentially. Inside this loop, Odoo recursively runs '_check_entire_pack()', forcing a full database evaluation of all 400+ delivery lines for every single line adjusted. This results in heavy, redundant processing.

Fix:
Used a context flag `bypass_entire_pack=True` to silence the '_check_entire_pack()' validation while looping through individual line adjustments. Once the loop completes, the package validation is called exactly once in batch for all affected pickings, preserving data integrity while eliminating redundant database queries.

Steps to Reproduce:
1. Have a product tracked by Lot and Package.
2. Have an open delivery order in Ready state (stock reserved) containing 400 or more lines of this product, one package per line.
3. Go to Inventory → Physical Inventory.
4. Set the counted quantity of any reserved bag to 0.
5. Click Apply.
6. Observe that the system takes time to process this single change.
7. Unreserve the delivery order.
8. Perform the same steps as mentioned above.
9. Inventory adjustment is much faster.

opw-6234885

---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: odoo/odoo#270228

Module: l10n_it_pos

Steps to reproduce:
- In the POS settings, enable "Automatic Receipt Printing";
- Enable "ePos Printer" to make the "Skip Preview Screen" option appear;
- Disable "Skip Preview Screen";
- Disable "ePos Printer";
- Set up an Italian Fiscal Printer;
- Open a POS session and process a first order. Issue: After the first receipt, no other messages (price display, receipt, open register) are sent to the fiscal printer. A page reload is required.

Issue: After the first receipt, no other messages (price display, receipt, open register) are sent to the fiscal printer. A page reload is required.

Cause:
When "Automatic Receipt Printing" is true but "Skip Preview Screen" is false, a race condition occurs. `afterOrderValidation` triggers a print job while simultaneously transitioning to the `ReceiptScreen`. When the `ReceiptScreen` mounts, it triggers a second fiscal print job before the first has resolved. This creates a deadlock in `toHtml` of  `renderService`, permanently blocking the printer queue.

Solution:
Since the italian localisation sending the receipt to the fiscal printer is mandatory, the printing route is now tied to the "Skip Preview Screen" option.

Enterprise PR: https://github.com/odoo/enterprise/pull/112654

[opw-5979212](https://www.odoo.com/odoo/project/49/tasks/5979212)

---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: odoo/odoo#270343
Forward-Port-Of: odoo/odoo#256932

Module: l10n_it_pos

Steps to reproduce:
- In the POS settings, enable "Automatic Receipt Printing";
- Enable "ePos Printer" to make the "Skip Preview Screen" option appear;
- Disable "Skip Preview Screen";
- Disable "ePos Printer";
- Set up an Italian Fiscal Printer;
- Open a POS session and process a first order.

Issue: After the first receipt, no other messages (price display, receipt, open register) are sent to the fiscal printer. A page reload is required.

Cause:
When "Automatic Receipt Printing" is true but "Skip Preview Screen" is false, a race condition occurs. `afterOrderValidation` triggers a print job while simultaneously transitioning to the `ReceiptScreen`. When the `ReceiptScreen` mounts, it triggers a second fiscal print job before the first has resolved. This creates a deadlock in `toHtml` of  `renderService`, permanently blocking the printer queue.

Solution:
Since the italian localisation sending the receipt to the fiscal printer is mandatory, the printing route is now tied to the "Skip Preview Screen" option.
UI settings are adjusted to hide the redundant auto-print checkbox when an IT fiscal printer is configured.

Community PR: https://github.com/odoo/odoo/pull/256932

[opw-5979212](https://www.odoo.com/odoo/project/49/tasks/5979212)

Forward-Port-Of: odoo/enterprise#120747
Forward-Port-Of: odoo/enterprise#112654