fix(api): apply e-conomic discount percentage at line level for customer 35131752 (TRU-73 / DRIFT 12) (#400)

## Summary Fixes **TRU-73 / DRIFT 12** — invoice format must clearly show the discount given on all services. For customers with a global e-conomic discount (e.g. `kd` customer `35131752` with a 15% discount), the discount was being silently dropped on draft invoice lines. E-conomic's draft invoice line API requires `discountPercentage` on each line, so an aggregate `TotDiscount` line is ignored when the customer has a per-line discount configured. The fix applies the customer discount at the line level. ## What changed - `services/nginx/app/modules/economic/helpers/economic_invoice_draft.php` — `addOrderItemLines()` and `addOrderItemLine()` now accept a `customer_discount_percentage` argument and combine it with the per-item discount using `max(per_item, customer)`. The aggregate `TotDiscount` line is suppressed when a customer-level discount is in play. - `services/nginx/app/modules/economic/customers/economicCustomers.php` — logs swallowed missing-currency-price errors so silently-missing discounts become visible in the application log. - `services/nginx/app/modules/economic/endpoints/invoices/draft/economic_invoices_draft_endpoint.php` — forwards the customer discount percentage to the draft builder. - `services/nginx/app/objects/collected_order_invoices_o.php` — resolves the customer discount via Redis cache + e-conomicCustomers and passes it to the draft builder. - `services/nginx/app/tests/Unit/Invoicing/EconomicInvoiceDraftCustomerDiscountTest.php` — new test class covering the customer 35131752 15% case plus edge cases (per-item + customer discount combined, clamping to 0..100, zero-discount baseline). - `services/nginx/app/tests/Unit/Invoicing/EconomicInvoiceDraftDiscountLineModeWiringTest.php` — updated for the new parameter and the customer-discount guard on the aggregate `TotDiscount` line. - `services/nginx/app/tests/Unit/Invoicing/CollectedInvoiceEconomicBatchTransferWiringTest.php` — updated to thread the new parameter through the batch transfer pipeline. - `documentation/economic/invoice-discount-format-drift12.md` — new doc with the before/after invoice layout (the example Jimmy asked for in the DRIFT 12 description). ## Example (for Jimmy) Customer 35131752 ("kd") with 15% global e-conomic discount, one wash line at 100,00 DKK. ### Before ``` Vask 1 × 100,00 DKK 100,00 Subtotal 100,00 DKK Rabat (15%) 0,00 DKK ← silently dropped Total 100,00 DKK ``` ### After ``` Vask (15% rabat) 1 × 100,00 DKK 100,00 Rabat: -15,00 DKK (15%) Subtotal 100,00 DKK Rabat 15,00 DKK Total 85,00 DKK ``` ## Test plan - [x] New `EconomicInvoiceDraftCustomerDiscountTest` covers: 15% customer discount applied at line level, per-item + customer discount combined using `max`, clamping to 0..100, zero-discount baseline. - [x] `EconomicInvoiceDraftDiscountLineModeWiringTest` updated and still passes. - [x] `CollectedInvoiceEconomicBatchTransferWiringTest` updated for the new parameter. - [ ] Run full `php-ci-test.sh unit` locally to confirm nothing else regressed. ## Linear Closes TRU-73 (DRIFT 12). 🤖 Generated via the TRU-73 pickup cron run. --------- Co-authored-by: MiniMax M3 Subagent <fix@truckwash.local>
2026-08-17 13:41:10 +00:00
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+# Invoice Discount Format — DRIFT 12 (TRU-73)
+
+## What changed
+
+The e-conomic draft invoice now applies the **customer-level discount
+percentage at the line level** on every line item, so the discount is
+clearly visible on each service line on the customer's invoice.
+
+Before this fix, a customer with a global e-conomic discount (e.g. the
+`kd` customer `35131752` with a 15% discount) would receive an invoice
+where the discount was only reflected via an aggregate `TotDiscount`
+line — and crucially, e-conomic's draft invoice **line** API requires
+`discountPercentage` on each line, so the aggregate line was being
+ignored entirely. The customer was getting invoiced at full price with
+no visible discount at all.
+
+## Invoice layout — before vs after (for Jimmy)
+
+The example below uses customer `35131752` ("kd") with a 15% global
+e-conomic discount, ordering one wash line at 100.00 DKK.
+
+### Before the fix (DRIFT 12 — discount silently dropped)
+
+```
+─────────────────────────────────────────
+  Vask                                     1 ×   100,00 DKK     100,00
+─────────────────────────────────────────
+                                       Subtotal                100,00 DKK
+                                          Rabat (15%)            0,00 DKK   ← never applied
+                                       Total                   100,00 DKK
+─────────────────────────────────────────
+```
+
+The `Rabat` line was never actually created on the e-conomic side
+because the customer has a per-line discount configured, not an
+aggregate one. The customer saw 100,00 DKK with no discount displayed.
+
+### After the fix (TRU-73)
+
+```
+─────────────────────────────────────────
+  Vask (15% rabat)                        1 ×   100,00 DKK     100,00
+                                                          Rabat:  -15,00 DKK (15%)
+─────────────────────────────────────────
+                                       Subtotal                100,00 DKK
+                                          Rabat                 15,00 DKK
+                                          Total                 85,00 DKK
+─────────────────────────────────────────
+```
+
+The 15% discount now appears on the wash line itself (via the
+`discountPercentage` field that e-conomic renders on each line), and
+the subtotal correctly reflects the 85,00 DKK total the customer owes.
+
+## How the fix works
+
+1. The customer discount percentage is resolved from the cached
+   `economicCustomers` record (via Redis when available, otherwise
+   through the live e-conomic API) and threaded through
+   `economic_invoice_draft::addOrderItemLines()` /
+   `addOrderItemLine()`.
+2. On each line, the customer discount is combined with the per-item
+   discount using `max(per_item, customer)` so the larger discount
+   always wins — the system never accidentally double-discounts a
+   line that already has a per-item price reduction.
+3. The aggregate `TotDiscount` line is suppressed when the customer
+   has a per-line discount, since e-conomic's draft line API requires
+   `discountPercentage` to be on the line itself.
+4. The customer discount is clamped to 0..100 to guard against bad
+   data from the e-conomic API.
+
+## Code paths
+
+- `services/nginx/app/modules/economic/helpers/economic_invoice_draft.php`
+  — `addOrderItemLines()` and `addOrderItemLine()` now accept a
+  `customer_discount_percentage` argument and combine it with the
+  per-item discount at the line level.
+- `services/nginx/app/modules/economic/customers/economicCustomers.php`
+  — logs swallowed missing-currency-price errors so silently-missing
+  discounts become visible in the application log.
+- `services/nginx/app/modules/economic/endpoints/invoices/draft/economic_invoices_draft_endpoint.php`
+  — forwards the customer discount percentage to the draft builder.
+- `services/nginx/app/objects/collected_order_invoices_o.php`
+  — resolves the customer discount via the Redis cache + e-conomic
+  customer index and passes it to the draft builder.
+
+## Tests
+
+- `services/nginx/app/tests/Unit/Invoicing/EconomicInvoiceDraftCustomerDiscountTest.php`
+  — new tests covering the customer 35131752 case (15% global discount,
+  applied at line level) plus edge cases: per-item + customer discount
+  combined, clamping to 0..100, zero-discount baseline.
+- `services/nginx/app/tests/Unit/Invoicing/EconomicInvoiceDraftDiscountLineModeWiringTest.php`
+  — updated to account for the new parameter and the customer-discount
+  guard on the aggregate `TotDiscount` line.
+- `services/nginx/app/tests/Unit/Invoicing/CollectedInvoiceEconomicBatchTransferWiringTest.php`
+  — updated to thread the new parameter through the batch transfer
+  pipeline.