To reproduce the issue:

- Setup tax periodicity to "trimester"
- Create a report evaluating something with previous_tax_period date_scope (real cases tend to do that for carryover ; see monthly Italian tax report for an example)
- Create the appropriate data so that in the current trimester, the report line evaluates to 42, and to 1 in the previous trimester
- Open the report for the second month of the trimester => The line has value 42, while it should have 1.

This happens because the date bounds for previous_tax_period were computed too naively, considering the date_from was always the first day of the tax period. The first day of the second month of the trimester, it's not the case, and we return the period boundaries of the day before that day. That day is the last day of the first month of the trimester, but belongs to the same trimester, so it's the same tax period. Therefore, we display the value of the current tax period, which is wrong.

Forward-Port-Of: odoo/enterprise#110504

Case 1:
---
**Steps to produce:**
- Install `pos_sale` module.
- Enable `Automatic Invoice` in settings
- Create a new SO with product price 1000.
- In `Other Info`, set `Online Payment` to 30%.
- Preview > make payment > down payment of 300 is created in SO.
- In POS, open Furniture Shop register > Actions > Quotation/Order > select the SO > settle order.

**Issue:**
- The down payment line is added twice in the POS order.

**Root cause:**
- At [1], `sale_order.amount_paid` = 300, so `addDownPaymentProductOrderlineToOrder` adds the line in order.
- At [2], the down payment line from the SO is added again.
- Here, when `Automatic invoice` is on and we make the online payment
  then `amount_paid` is updated and the downpayment invoice is also created.
- So, we have also downpayment line in sale order also.

**Solution:**
- Ensure that if a downpayment line has already been added to the POS order,
  the first downpayment line matching `amount_paid` is skipped.

[1]: https://github.com/odoo/odoo/blob/54a62bdbe927108a7f85374db26787f8ba45f6ac/addons/pos_sale/static/src/overrides/models/pos_store.js#L88-L93
[2]: https://github.com/odoo/odoo/blob/54a62bdbe927108a7f85374db26787f8ba45f6ac/addons/pos_sale/static/src/overrides/models/pos_store.js#L109-L111

Before:
<img width="484" height="279" alt="image" src="https://github.com/user-attachments/assets/c803c9bd-0751-4a90-81f4-8fb3da3b393e" />


After:
<img width="490" height="235" alt="image" src="https://github.com/user-attachments/assets/2ec4ac43-1db3-4c2e-bfcf-8c52a4830dac" />

Case 2:
---
**Steps to produce:**
- Install `pos_sale` module.
- Enable `Automatic Invoice` in settings
- Create a new SO with product price 1000.
- In `Other Info`, set `Online Payment` to 30%.
- Preview > make payment.

**Issue:**
-The computed value of amount_unpaid is 400, whereas it should be 700.

**Root cause:**
- When Automatic Invoice is enabled and an online payment is made, the invoice
  is automatically created and amount_paid is also updated.
- At [3], the logic subtracts both the total invoice amount and amount_paid from
  the actual total, which results in an incorrect calculation.

**Solution:**
- When an online payment is made, a transaction is created and linked to
  an invoice.
- While computing the total invoice amount, if the transaction’s invoice ID is
  encountered again, it should be skipped to avoid double-counting.

[3]: https://github.com/odoo/odoo/blob/75f6be6744006ed1a3c0857881822723f90f5d4a/addons/pos_sale/models/sale_order.py#L46-L51

opw-5415404
---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

How to reproduce :
- Create a product
- Create an attribute with a value set to "free text"
- Add 2 different vendors to the purchase tab of the product with different Vendor Code and/or Vendor Name
- Put Dropship as the route for the product to create a PO on a SO confirmation
- Create a SO with that product
- Confirm the SO and go to the PO
- Change the vendor in the SO

The problem :
The Vendor Code and/or Vendor Name does not change correctly in the product description

Why :
The way the description generation for a change in a purchase order line works as follows : Create a collection of default descriptions based on the product and the different vendors. If the collection contains the current description, it means the description was not changed by the user and it can be modified. This is done to prevent resetting a custom description made by an user.

This logic is pretty broken because the code that generate the description when going from a PO to a SO and the code that generate the description when changing the PO partner are different. This makes it so the current description is almost never found in the list of default descriptions.

It looks tempting to try to "resynchronize" those part of the code so the description generation is the same in both cases. This would be done by overriding the _get_product_purchase_description method in the purchase_stock module and using the product_description_variants field. Sadly, this does not work because it conflicts with the purchase_product_matrix module and its own override of that method.

The fix that I implemented checks that the Vendor Code and Name are the right one every time the description is computed following a change.

opw-5888233

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

In `ThreadedServer,` the http daemon will create threads to handle incoming requests. The creation of these threads doesn't wait until the registry is loaded because the request could be serving static files. In the WSGI application entry point `__call__`, the threads will be going into `self.get_static_file` and up until this point, there's no locking whatsoever on these threads. Inside `get_static_file`, the `self.statics` lazy_property is evaluated which will walk the addons path.

Before this PR, the order of the conditions in the or statement will always evaluate the lazy property regardless of the other parts of the condition. This means that every single request that comes in will do an unnecessary `os.listdir` on all addons paths.

For customers with a very large and deeply nested addons path like in opw-5877522 (they had over 93K dirs), this is a tremendous load on the system when there are multiple threads doing that due to the amount of syscalls involved for no reason whatsoever. This is especially worse on SH because disks are not local, so an individual syscall is more expensive.

This is slowing down all requests as well as the registry loading time which is a prerequisite for any non-static request.

This PR simply reorders this check to only evaluate the self.statics property if all other parts of the condition are False. This means it'll only have to do this expensive `os.list` for a fewer number of requests which are much more unlikely to coincide at the startup of a worker. On top of that it's a better optimization to avoid doing this expensive check for every request.

Benchmarks

|No. files in addons path| No. concurrent threads  | Registry loading time Before PR | Registry loading time After PR |
|--------|--------|--------|--------|
| 93447 | 5  | 53.23 s  | 4 s  |



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

Forward-Port-Of: odoo/odoo#254660