# i18n inventory — dynamic/backend content requiring message-code treatment

Static UI chrome (navigation, dashboard, forms, filters, dialogs, empty/loading states,
Demo Guide, About page, accessibility labels) was already moved to the `i18next`
namespace system in the prior task and is not re-inventoried here in full — see
`docs/final-product-polish/audit.md` and `docs/final-product-polish/i18n-inventory.md`
for that pass. This inventory covers only the sources confirmed still bypassing
translation (per `current-gap-audit.md`), the fix chosen, and the tests that verify it.

| # | Source | Location | Static/dynamic | Fix | Tests |
|---|--------|----------|-----------------|-----|-------|
| 1 | Duplicate-customer evidence signals | `backend/app/services/data_quality.py::_scan_duplicate_customers` | dynamic | `evidence.signals: [{code, params}]` (`duplicate.exact_email`, `duplicate.exact_phone`, `duplicate.same_postal_code`, `duplicate.similar_name` + score param); frontend maps code→localized phrase | `test_data_quality.py::test_duplicate_customer_evidence_has_structured_signals`; Playwright DQ evidence-language test |
| 2 | Missing-required-field evidence | `_scan_missing_required_fields` | dynamic | `evidence.signals: [{code: "missing_field", params: {field}}]`; frontend maps `field` through the existing `CUSTOMER_FIELD_LABELS`/`VEHICLE_FIELD_LABELS`-equivalent i18n keys | same |
| 3 | Booking-overlap evidence | `_scan_booking_overlaps` | dynamic | `evidence.signals: [{code: "overlap.reserved_bookings", params: {refs: [...]}}]` | same |
| 4 | Vehicle-status-conflict evidence | `_scan_vehicle_status_conflicts` | dynamic | replaced entirely by the new `evaluate_vehicle_status()` evaluator's `recommendation_code`; scanner reuses the evaluator instead of its own reason strings | new evaluator unit tests |
| 5 | Odometer-regression evidence | `_scan_odometer_regressions` | dynamic | `evidence.signals: [{code: "odometer.regression", params: {later_ref, later_km, earlier_ref, earlier_km}}]` | same |
| 6 | Status-recommendation reason | `_recommend_vehicle_status` / new `evaluate_vehicle_status` | dynamic | `recommendation_code` + `facts` (structured), no free prose from the backend at all; frontend renders the full explanation from `quality:statusRecommendation.codes.<code>` | evaluator unit tests + preview/apply contract tests |
| 7 | Return status reason | `backend/app/services/returns.py::_derive_vehicle_status_with_reason` | dynamic | `status_reason_code` + `params` alongside the existing human string (kept for backward-compat, demoted to technical fallback) | `test_returns.py` updated; Playwright return-flow-language test |
| 8 | Automation `last_error` | `dispatcher.py` / seed data, rendered in `Automation.tsx` | dynamic | known-cause codes (`n8n.connection_timeout`, `n8n.http_error`, etc.) mapped to a localized summary + "what happened / what's pending / what retry does"; raw string demoted to Technical details | Playwright automation-language test |
| 9 | `aria-label="Demo scenario"` | `frontend/src/pages/BookingDetail.tsx:76` | static, just un-wired | `t("returns:scenario.ariaLabel")`, 3 locales | i18n-coverage (key parity) + route-matrix test |
| 10 | Brand name (`common:appName` + 8 embedded mentions) | see gap audit §1 | static, wrongly translatable | `PRODUCT_NAME` constant, `{{productName}}` interpolation | new brand-invariant test |

## Message-code mapping module

Centralised in `frontend/src/i18n/messageCodes.ts` (new): a single `resolveMessageCode(t, code, params)` helper used by the Data Quality evidence renderer, the status-recommendation panel, the return-result panel, and the automation ledger, so there is one place mapping `code → i18next key` rather than per-page switch statements.