feat(rates): last-mile rate rules with bulk per-ton-km and container distance bands

- rates: min_km/max_km columns, PER_TON_KM unit, ETB|USD currency for last mile
- extend UQ_rates_pattern with band start; overlap + shape validation
- shared last-mile charge resolver; approve-dialog price estimate endpoint
- delivery-fee invoice prices via rules, falls back to vehicle price/km
- backoffice: last-mile rate form (mode, container type, band, currency)

apps/edr-freight-web/backoffice/src/pages/ruleEngine/RuleEngineResourcePage.tsx

@@ -584,10 +584,30 @@ const RuleEngineResourcePage = () => {
       // treats them as ALWAYS. Surcharges (Applies to = Other) keep their
       // chosen trigger.
       const isSurcharge = values.appliesTo === "OTHER";
+      // Last mile: the form's calculation mode picks the unit (bulk = per
+      // ton·km, container = per km + distance band) and the currency stays as
+      // chosen (birr or dollar). Everything else remains USD-only.
+      const isLastMile = values.appliesTo === "LAST_MILE";
+      const { lastMileMode, ...rest } = values;
       payload = {
-        ...values,
-        currency: "USD",
+        ...rest,
+        currency: isLastMile ? (values.currency ?? "ETB") : "USD",
         trigger: isSurcharge ? values.trigger : "ALWAYS",
+        ...(isLastMile
+          ? lastMileMode === "BULK"
+            ? {
+                rateUnit: "PER_TON_KM",
+                containerTypeId: undefined,
+                minKm: undefined,
+                maxKm: undefined,
+              }
+            : {
+                rateUnit: "PER_KM",
+                // Empty "To km" means an open-ended band — send null so an
+                // edit can clear a previously-set ceiling.
+                maxKm: values.maxKm ?? null,
+              }
+          : {}),
       };
       // Editing a LIVE rate files a change request — the rate keeps charging
       // its current value until an approver applies it. DRAFT rates fall

apps/edr-freight-web/backoffice/src/pages/ruleEngine/config/resources.ts

@@ -267,8 +267,10 @@ const unitsForShape = (
     case "INTERCITY":
       return ["PER_CONTAINER", "PER_TON", "PER_WAGON", "PER_KM"];
     case "FIRST_MILE":
-    case "LAST_MILE":
       return ["PER_CONTAINER", "PER_TON", "PER_KM", "FLAT"];
+    case "LAST_MILE":
+      // PER_KM = container mode (distance-banded), PER_TON_KM = bulk mode.
+      return ["PER_KM", "PER_TON_KM", "PER_CONTAINER", "PER_TON", "FLAT"];
     default:
       return ["FLAT"];
   }
@@ -846,6 +848,9 @@ export const RULE_ENGINE_RESOURCES: RuleEngineResourceConfig[] = [
       },
       { id: "rateValue", header: "Value", accessorKey: "rateValue", format: "currency" },
       { id: "rateUnit", header: "Unit", accessorKey: "rateUnit" },
+      // Container last-mile distance bands; blank for every other rate shape.
+      { id: "minKm", header: "From km", accessorKey: "minKm", format: "number" },
+      { id: "maxKm", header: "To km", accessorKey: "maxKm", format: "number" },
       { id: "status", header: "Status", accessorKey: "status", format: "rateStatus" },
     ],
     formFields: [
@@ -958,6 +963,65 @@ export const RULE_ENGINE_RESOURCES: RuleEngineResourceConfig[] = [
         getInitialValue: (record) =>
           record.rateType === "INTERCITY_BULK" ? "BULK" : "CONTAINER",
       },
+      // ── Last mile — two calculation modes ─────────────────────────────────
+      // Bulk bills per ton per km (price = tons × km × rate); Container bills
+      // per km, banded by distance range with one rate row per container type
+      // per band (price = km × rate × quantity).
+      {
+        name: "lastMileMode",
+        label: "Calculation mode",
+        type: "select",
+        required: true,
+        options: [
+          { label: "Bulk (per ton per km)", value: "BULK" },
+          { label: "Container (per km, distance-banded)", value: "CONTAINER" },
+        ],
+        description:
+          "Bulk: price = tons × km × rate. Container: price = km × band rate × quantity, one rate per container type per distance band.",
+        showWhen: { field: "appliesTo", equals: ["LAST_MILE"] },
+        // Not a stored column: the mode is recorded in the unit the API keeps.
+        getInitialValue: (record) =>
+          record.rateUnit === "PER_TON_KM" ? "BULK" : "CONTAINER",
+      },
+      {
+        name: "containerTypeId",
+        label: "Container type",
+        type: "select",
+        required: true,
+        placeholder: "Which container type this band prices",
+        description: "20ft and 40ft price differently — one rate per type per band.",
+        showIf: (v) =>
+          v.appliesTo === "LAST_MILE" && v.lastMileMode === "CONTAINER",
+      },
+      {
+        name: "minKm",
+        label: "From km",
+        type: "number",
+        required: true,
+        placeholder: "0",
+        description: "Band start (inclusive). Use 0 for the first band.",
+        showIf: (v) =>
+          v.appliesTo === "LAST_MILE" && v.lastMileMode === "CONTAINER",
+      },
+      {
+        name: "maxKm",
+        label: "To km",
+        type: "number",
+        optional: true,
+        placeholder: "Leave empty for no upper limit",
+        description: "Band end (exclusive) — a 0–30 band covers up to but not including 30 km.",
+        showIf: (v) =>
+          v.appliesTo === "LAST_MILE" && v.lastMileMode === "CONTAINER",
+      },
+      {
+        name: "currency",
+        label: "Currency",
+        type: "select",
+        required: true,
+        options: CURRENCIES,
+        showWhen: { field: "appliesTo", equals: ["LAST_MILE"] },
+        getInitialValue: (record) => String(record.currency ?? "ETB"),
+      },
       // ── Container type — Container freight, container-kind intercity, and
       // the empty-container return surcharge (20ft vs 40ft price differently) ─
       {
@@ -1002,10 +1066,29 @@ export const RULE_ENGINE_RESOURCES: RuleEngineResourceConfig[] = [
         placeholder: "Where the leg ends",
         showIf: isRouteScopedRate,
       },
-      { name: "rateValue", label: "Rate value", type: "number", required: true, suffix: "USD" },
+      {
+        name: "rateValue",
+        label: "Rate value",
+        type: "number",
+        required: true,
+        suffix: "USD",
+        showIf: (v) => v.appliesTo !== "LAST_MILE",
+      },
+      // Last-mile rates carry their own currency (birr or dollar) and the
+      // value is a per-km / per-ton·km price, so no hardcoded USD suffix.
+      {
+        name: "rateValue",
+        label: "Rate value",
+        type: "number",
+        required: true,
+        description:
+          "Container mode: price per km for this band. Bulk mode: price per ton per km.",
+        showWhen: { field: "appliesTo", equals: ["LAST_MILE"] },
+      },
       // Unit choices are driven by the rate shape (appliesTo + trigger). Overweight
       // is always per excess ton, so the unit field is hidden for it — the API
-      // forces PER_TON regardless.
+      // forces PER_TON regardless. Last mile derives its unit from the
+      // calculation mode instead.
       {
         name: "rateUnit",
         label: "Rate unit",
@@ -1014,7 +1097,9 @@ export const RULE_ENGINE_RESOURCES: RuleEngineResourceConfig[] = [
         optionsFromValues: rateUnitOptions,
         description:
           "Weighting basis — options depend on what the rate applies to, and for bulk on how the picked commodity is counted (per ton or per item).",
-        hideWhen: { field: "trigger", equals: ["OVERWEIGHT"] },
+        showIf: (v) =>
+          String(v.trigger ?? "") !== "OVERWEIGHT" &&
+          String(v.appliesTo ?? "") !== "LAST_MILE",
       },
     ],
   },