feat(eims): derive buyer City/Country from company profile, not global config

City: EimsMapperContext.buyerCity was declared but never wired anywhere —
always null, silently, for every buyer. No dedicated city column on Company;
derives from Zone via a new EIMS_BUYER_CITY_CODES map, same lookup mechanism
as Region/Wereda but optional (an unmapped zone resolves to null rather than
throwing) — MoR has already accepted a live filing with City null.

Country: previously a single flat EIMS_BUYER_COUNTRY_CODE applied to every
buyer regardless of Company.country. Now reads company.country, resolved via
a new EIMS_BUYER_COUNTRY_CODES name-to-code map; the flat env var becomes a
domestic-only fallback (applies only when country is empty/Ethiopia), so an
unmapped foreign buyer fails locally instead of silently filing as Ethiopia.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/edr-freight-api/src/modules/billing/eims-invoice.mapper.ts

@@ -234,8 +234,13 @@ export interface EimsMapperContext {
    * from a registered invoice").
    */
   relatedDocument?: string | null;
-  /** MoR numeric country code for the buyer; our DB stores the country name. */
+  /**
+   * Domestic fallback only, applied when `company.country` is empty or "Ethiopia" and not already
+   * in `buyerCountryCodes` — see that field. Never applied to a genuinely foreign buyer.
+   */
   buyerCountryCode?: string | null;
+  /** Country name → MoR code. Format unconfirmed, so looked up by name only, not digit-validated. */
+  buyerCountryCodes: Record<string, string>;
   /**
    * Region name → MoR numeric code, for buyers whose stored region is free text.
    *
@@ -252,9 +257,15 @@ export interface EimsMapperContext {
    * fail locally on an unmapped name rather than file a guess.
    */
   buyerWeredaCodes: Record<string, string>;
+  /**
+   * Buyer *zone* name → MoR City code. `Company` has no dedicated city column; Zone is the
+   * closest match in EDR's own data. Unlike Region/Wereda, City is optional — MoR has already
+   * accepted a live filing with it null — so an unmapped zone resolves to null, it does not fail
+   * the mapping.
+   */
+  buyerCityCodes: Record<string, string>;
   buyerIdType?: string | null;
   buyerIdNumber?: string | null;
-  buyerCity?: string | null;
   /** Required when the invoice currency is not ETB. */
   exchangeRate?: number | null;
   invoiceDiscount?: number | null;
@@ -299,17 +310,22 @@ export const formatEimsDate = (issuedAt: Date): string =>
  * exchange rate.
  */
 /**
- * A buyer's location value (Region or Wereda) as a MoR code: passed through when already numeric,
- * otherwise looked up by name (case- and space-insensitive). Throws when neither applies — sending
- * a guessed code onto a tax document is worse than refusing to file.
+ * A buyer's location value (Region, Wereda or City) as a MoR code: passed through when already
+ * numeric, otherwise looked up by name (case- and space-insensitive).
+ *
+ * Region/Wereda are required: an unmapped value throws — sending a guessed code onto a tax
+ * document is worse than refusing to file. City is optional (`required: false`, City's own
+ * caller) — MoR has already accepted a live filing with it null, so an unmapped zone resolves to
+ * null instead of blocking the invoice.
  */
 function resolveLocationCode(
-  field: "Region" | "Wereda",
+  field: "Region" | "Wereda" | "City",
   value: string | null | undefined,
   codes: Record<string, string>,
   envVar: string,
   invoiceNumber: string,
-): string {
+  opts: { required?: boolean } = {},
+): string | null {
   const raw = (value ?? "").trim();
   if (LOCATION_CODE.test(raw)) return raw;
 
@@ -319,12 +335,42 @@ function resolveLocationCode(
   )?.[1];
   if (mapped && LOCATION_CODE.test(mapped)) return mapped;
 
+  if (opts.required === false) return null;
+
   throw new Error(
     `EIMS mapping: invoice ${invoiceNumber} has buyer ${field} ${raw ? `"${raw}"` : "(unset)"}, ` +
       `which is not a MoR ${field} code and has no mapping. Add it to ${envVar}.`,
   );
 }
 
+/**
+ * A buyer's `Country` as a MoR code: looked up by name in `codes` first; when unmapped, applies
+ * `domesticFallback` only if the stored country is empty or "Ethiopia" (the DB column's default).
+ * A genuinely foreign, unmapped country throws rather than silently filing as Ethiopia — same
+ * "fail locally, don't guess" rule as `resolveLocationCode`, but never digit-validated: MoR's
+ * Country code format is unconfirmed, unlike Region/Wereda's proven `^[0-9]{1,3}$`.
+ */
+function resolveCountryCode(
+  country: string | null | undefined,
+  codes: Record<string, string>,
+  domesticFallback: string | null,
+  invoiceNumber: string,
+): string | null {
+  const raw = (country ?? "").trim();
+  const key = raw.toLowerCase().replace(/\s+/g, " ");
+  const mapped = Object.entries(codes).find(
+    ([name]) => name.trim().toLowerCase().replace(/\s+/g, " ") === key,
+  )?.[1];
+  if (mapped) return mapped;
+
+  if ((!raw || key === "ethiopia") && domesticFallback) return domesticFallback;
+
+  throw new Error(
+    `EIMS mapping: invoice ${invoiceNumber} has buyer Country "${raw || "(unset)"}", which has no ` +
+      "MoR country code mapping. Add it to EIMS_BUYER_COUNTRY_CODES.",
+  );
+}
+
 export function toEimsInvoice(
   invoice: EimsMapperInvoice,
   seller: EimsSellerDetails,
@@ -440,7 +486,16 @@ export function toEimsInvoice(
 
   return {
     BuyerDetails: {
-      City: context.buyerCity ?? null,
+      // No dedicated city column on Company — Zone is the closest match; optional (see
+      // resolveLocationCode's City comment).
+      City: resolveLocationCode(
+        "City",
+        company.zone,
+        context.buyerCityCodes,
+        "EIMS_BUYER_CITY_CODES",
+        invoice.invoiceNumber,
+        { required: false },
+      ),
       Email: company.email ?? null,
       HouseNumber: company.houseNo ?? null,
       IdNumber: context.buyerIdNumber ?? null,
@@ -455,7 +510,12 @@ export function toEimsInvoice(
         "EIMS_BUYER_REGION_CODES",
         invoice.invoiceNumber,
       ),
-      Country: context.buyerCountryCode ?? null,
+      Country: resolveCountryCode(
+        company.country,
+        context.buyerCountryCodes,
+        context.buyerCountryCode ?? null,
+        invoice.invoiceNumber,
+      ),
       Zone: company.zone ?? null,
       Kebele: company.kebele ?? null,
       VatNumber: company.vatNumber ?? null,