Criptomart/red-supermercados-coop#17 add account_invoice_triple_discount_readonly: fix write discount2 and dicount3 columns. Make discount (total) readonly

account_invoice_triple_discount_readonly/README.md

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+# Account Invoice Triple Discount Readonly
+
+## Description
+
+This module fixes a bug in `account_invoice_triple_discount` when combined with `purchase_triple_discount`.
+
+### Original Problem
+
+In purchase orders, when configuring a discount in the `discount2` or `discount3` columns, upon saving:
+- All discounts were accumulated in the `discount1` column
+- The `discount2` and `discount3` fields were reset to zero
+
+This occurred because the original mixin's `write` method always reset `discount2` and `discount3` to 0 when the computed `discount` field was included in the write (which happens when any discount is modified).
+
+### Solution
+
+The module overrides the `write` method of `triple.discount.mixin` to:
+1. Detect if `discount1`, `discount2` or `discount3` are being explicitly modified
+2. If there are explicit discounts, ignore the computed `discount` field
+3. If only the `discount` field comes, maintain legacy behavior (map to `discount1` and reset the rest)
+
+Additionally, it makes the `discount` field (total discount) **readonly** in:
+- Partner form view (`res.partner`)
+- Supplier info in product form (`product.supplierinfo`)
+- Base mixin (`triple.discount.mixin`)
+
+This forces users to work only with the `discount1`, `discount2` and `discount3` columns, avoiding confusion.
+
+## Installation
+
+1. Make sure `account_invoice_triple_discount` and `purchase_triple_discount` are installed
+2. Update the module list
+3. Install `account_invoice_triple_discount_readonly`
+
+## Usage
+
+After installation:
+- The total discount field will be readonly and automatically calculated
+- Users must use discount1, discount2, and discount3 fields to set discounts
+- When saving, the individual discount values will be preserved correctly
+
+## Bug Tracker
+
+Bugs are tracked on [GitHub Issues](https://github.com/OCA/account-invoicing/issues).
+In case of trouble, please check there if your issue has already been reported.
+
+## Credits
+
+### Contributors
+
+* Coop Makers
+
+### Maintainers
+
+This module is maintained by the OCA.
+
+## Compatibility
+
+- Odoo 16.0
+- account_invoice_triple_discount
+- purchase_triple_discount