[19.0][ADD] website_sale_product_multiple_qty

[yankinmax]

This module extends the eCommerce flow to support Sales Multiples
(packaging quantities) directly on the product page, in the cart,
and in the product configurator.

When a product (or variant) has a Sales Multiple configured,
the quantity entered by the customer on the website is automatically
rounded to a valid multiple according to the interaction type.

The rounding logic is applied dynamically when the customer:

• Opens the product page
• Changes the product variant
• Clicks the "+" (increase) button
• Clicks the "–" (decrease) button
• Manually enters a quantity
• Presses Enter inside the quantity input
• Changes quantities in the cart

[yankinmax]

This PR is moved from OCA/sale-workflow:

• [19.0][ADD] website_sale_product_multiple_qty sale-workflow#4165

Hello @alexey-pelykh, I address your suggestions on the closed PR here.
Thanks again

[ivantodorovich]

Thanks @yankinmax !

[vvrossem]

Great work.
Note: I overlooked the JS part.

[ivantodorovich]

Depends on:

• [ADD] sale_product_multiple_qty sale-workflow#4143

[BhaveshHeliconia]

LGTM!

[alexey-pelykh]

Thanks for moving this over and working through the feedback from OCA/sale-workflow#4165, @yankinmax — I went back through each of my earlier points against the current diff:

• _get_sale_multiple_vals duplication — resolved. controllers/product_configurator.py now calls self.env["product.template"]._get_sale_multiple_vals(...) instead of carrying its own copy, so there's a single source of truth.
• Tests — resolved. tests/test_website_sale_product_multiple_qty.py plus the two tours (website_shop_product_multiple_qty / website_shop_checkout_product_multiple_qty) cover page load, +/- buttons and manual-input rounding.
• int(multiple_uom.factor) as the step — this was my main open question, and it's correct for 19.0. The UoM refactor made factor the absolute quantity (uom.uom._compute_factor: relative_factor * relative_uom_id.factor), so a "Pack of 5" yields factor == 5 and int(multiple_uom.factor) is the right step. My original concern was against the pre-18.0 semantics where factor was the inverse ratio (0.002 for a pack of 500) — that no longer applies here.
• Rounding epsilon — good: step * 1e-9 is now scaled to the step and carries an explanatory comment.
• _get_additionnal_combination_info spelling — matches the upstream super() name, so nothing to change.

The only outstanding item is the one you already flagged: Detect unreleased dependencies is red because test-requirements.txt pins sale_product_multiple_qty to refs/pull/4143/head. That clears once OCA/sale-workflow#4143 lands — nothing to do on your side until then.

Nice work.

Co-Reviewed-By: Claude Opus 4.8 noreply@anthropic.com