add hard capacity ceiling to weight limit rules

apps/edr-freight-web/backoffice/src/components/contracts/GlCreateBookingForm.tsx

@@ -444,6 +444,7 @@ export default function GlCreateBookingForm() {
 
   const displayTotal = serverTotal ?? priceTotal;
   const pairingErrors = validation?.pairingErrors ?? [];
+  const capacityErrors = validation?.capacityErrors ?? [];
   const overweightLines = validation?.overweightLines ?? [];
 
   const openPriceModal = () => {
@@ -459,6 +460,8 @@ export default function GlCreateBookingForm() {
     if (!contract || !windowOpen) return;
     // Never book past unresolved 20ft pairing hard-blocks.
     if (pairingErrors.length > 0) return;
+    // A line above the container type's max capacity can never book.
+    if (capacityErrors.length > 0) return;
     const payload = buildPayload();
     if (!payload) return;
 
@@ -938,6 +941,28 @@ export default function GlCreateBookingForm() {
               </Alert>
             )}
 
+            {capacityErrors.length > 0 && (
+              <Alert
+                color="red"
+                variant="light"
+                radius="md"
+                icon={<AlertCircle size={16} />}
+                title="Cannot create booking — over maximum capacity"
+              >
+                <Stack gap={6}>
+                  {capacityErrors.map((msg, i) => (
+                    <Text key={i} fz="sm" c="red.8">
+                      {msg}
+                    </Text>
+                  ))}
+                  <Text fz="xs" c="red.7" mt={2}>
+                    Reduce the cargo weight or split it across more containers
+                    to book this shipment.
+                  </Text>
+                </Stack>
+              </Alert>
+            )}
+
             {overweightLines.length > 0 && (
               <Alert
                 color="yellow"
@@ -1023,7 +1048,9 @@ export default function GlCreateBookingForm() {
                 leftSection={<CheckCircle2 size={16} />}
                 loading={mutations.createBooking.isPending}
                 disabled={
-                  validateShipmentMutation.isPending || pairingErrors.length > 0
+                  validateShipmentMutation.isPending ||
+                  pairingErrors.length > 0 ||
+                  capacityErrors.length > 0
                 }
                 onClick={handleSubmit}
               >

apps/edr-freight-web/backoffice/src/components/trainScheduling/ScheduleWorkspacePanel.tsx

@@ -1,4 +1,5 @@
 import { useMemo, useState } from "react";
+import { isAxiosError } from "axios";
 import {
   Badge,
   Box,
@@ -47,6 +48,18 @@ interface ScheduleWorkspacePanelProps {
 
 const GREEN = "var(--mantine-color-edr-green-6)";
 
+/** Pull the API's violation detail out of an error (e.g. "No CW3 wagon available…"). */
+function apiErrorMessage(error: unknown, fallback: string): string {
+  if (isAxiosError(error)) {
+    const data = error.response?.data as Record<string, unknown> | undefined;
+    const violations = data?.violations;
+    if (Array.isArray(violations) && violations.length) return violations.join(", ");
+    if (typeof data?.message === "string") return data.message;
+    if (Array.isArray(data?.message)) return (data.message as string[]).join(", ");
+  }
+  return fallback;
+}
+
 /**
  * Deadline + label for the window phase this schedule is currently in.
  * Phases run: window open (windowClosesAt) → document review (docReviewEndsAt)
@@ -198,8 +211,12 @@ export function ScheduleWorkspacePanel({
         onChanged();
         void poolQuery.refetch();
       })
-      .catch(() =>
-        toast({ title: "Could not add booking", variant: "destructive" }),
+      .catch((error) =>
+        toast({
+          title: "Could not add booking",
+          description: apiErrorMessage(error, "Validation failed — check capacity and status."),
+          variant: "destructive",
+        }),
       );
   };
 
@@ -211,8 +228,12 @@ export function ScheduleWorkspacePanel({
         onChanged();
         void poolQuery.refetch();
       })
-      .catch(() =>
-        toast({ title: "Could not remove booking", variant: "destructive" }),
+      .catch((error) =>
+        toast({
+          title: "Could not remove booking",
+          description: apiErrorMessage(error, "Please try again."),
+          variant: "destructive",
+        }),
       );
   };
 
@@ -226,8 +247,12 @@ export function ScheduleWorkspacePanel({
         onChanged();
         void poolQuery.refetch();
       })
-      .catch(() =>
-        toast({ title: "Could not reassign booking", variant: "destructive" }),
+      .catch((error) =>
+        toast({
+          title: "Could not reassign booking",
+          description: apiErrorMessage(error, "Target train may be closed or full."),
+          variant: "destructive",
+        }),
       );
   };