fix train builder and consolidation

apps/edr-freight-web/portal/src/pages/bookings/new-booking-form/step8-review.tsx

@@ -25,10 +25,11 @@ import {
 } from "lucide-react";
 import type { Freight } from "@/types";
 import {
+  calcWagons,
   type BookingFormInputValues,
   type BookingFormValues,
 } from "./schema";
-import { StepHeader } from "./shared";
+import { AlertBox, StepHeader } from "./shared";
 
 export const REVIEW_STEP_TARGETS = {
   contract: 1,
@@ -160,6 +161,12 @@ export function Step8Review({
           .join(", ")
       : "";
 
+  // 20ft containers must pair up (two per wagon) — an odd total blocks submit.
+  const { hasOddUnit: hasOdd20ft, ft20Wagons: twentyFtCount } =
+    values.cargoType === "container"
+      ? calcWagons(values.containers ?? [])
+      : { hasOddUnit: false, ft20Wagons: 0 };
+
   const isGeneralContract = values.bookingType === "general_contract";
   // Both one-time and general contracts take the bulk amount from the cargo step
   // (cargoWeight); general contracts no longer collect a per-route quantity.
@@ -529,10 +536,27 @@ export function Step8Review({
             </Paper>
 
             <Paper radius={20} p="lg" withBorder bg="white">
-              <Text size="sm" c="dimmed" mb="md">
-                Ready to submit. You'll review the unit rates before final
-                submission.
-              </Text>
+              {hasOdd20ft ? (
+                <Box mb="md">
+                  <AlertBox tone="error">
+                    <p className="font-semibold">
+                      Odd number of 20ft containers ({twentyFtCount})
+                    </p>
+                    <p className="mt-1 text-xs">
+                      20ft containers travel two per wagon, so they must be booked
+                      in even numbers. Go back to the cargo step and{" "}
+                      <strong>add one more 20ft container</strong> or{" "}
+                      <strong>remove one</strong> (e.g. {twentyFtCount + 1} or{" "}
+                      {twentyFtCount - 1} instead of {twentyFtCount}).
+                    </p>
+                  </AlertBox>
+                </Box>
+              ) : (
+                <Text size="sm" c="dimmed" mb="md">
+                  Ready to submit. You'll review the unit rates before final
+                  submission.
+                </Text>
+              )}
               <Stack gap="sm">
                 <Button
                   type="button"
@@ -543,7 +567,7 @@ export function Step8Review({
                   leftSection={<Send size={16} />}
                   onClick={onSubmit}
                   loading={submitPending}
-                  disabled={submitPending}
+                  disabled={submitPending || hasOdd20ft}
                 >
                   Submit
                 </Button>