implement exchange settings management and fallback rate handling

apps/edr-freight-web/backoffice/src/components/ruleEngine/RuleEngineFormDialog.tsx

@@ -153,11 +153,13 @@ const RuleEngineFormDialog = ({
     buildInitialValues(fields, initialRecord),
   );
   const [position, setPosition] = useState(RULE_ENGINE_POSITION_END);
+  const [fieldErrors, setFieldErrors] = useState<Record<string, string>>({});
 
   useEffect(() => {
     if (open) {
       setValues(buildInitialValues(fields, initialRecord));
       setPosition(RULE_ENGINE_POSITION_END);
+      setFieldErrors({});
     }
   }, [open, fields, initialRecord]);
 
@@ -185,6 +187,9 @@ const RuleEngineFormDialog = ({
   const formRows = useMemo(() => buildFormRows(visibleFields), [visibleFields]);
 
   const setField = (name: string, value: unknown) => {
+    setFieldErrors((current) =>
+      current[name] ? { ...current, [name]: "" } : current,
+    );
     setValues((current) => {
       const next = { ...current, [name]: value };
       // Changing what a rate applies to (or its surcharge trigger) can invalidate
@@ -223,6 +228,10 @@ const RuleEngineFormDialog = ({
   const handleSubmit = (event: React.FormEvent) => {
     event.preventDefault();
     const payload: Record<string, unknown> = {};
+    // Required selects that are empty block the submit and mark themselves,
+    // rather than posting an incomplete payload for the API to reject.
+    setFieldErrors({});
+    let blocked = false;
 
     for (const field of visibleFields) {
       // Derived fields always submit their computed value — never stale state.
@@ -241,7 +250,16 @@ const RuleEngineFormDialog = ({
         field.type === "select" &&
         (raw === "" || raw === RULE_ENGINE_SELECT_NONE)
       ) {
+        // A required select left empty must not silently submit nothing — the
+        // API rejects the payload with a message that reads as if the admin
+        // skipped a field they never saw cleared (e.g. yards reset by a trade
+        // direction change). Surface it on the field instead.
         if (!field.required) continue;
+        setFieldErrors((current) => ({
+          ...current,
+          [field.name]: `${field.label} is required.`,
+        }));
+        blocked = true;
       } else if (raw === "" || raw === undefined) {
         if (!field.required) continue;
         payload[field.name] = raw;
@@ -254,6 +272,8 @@ const RuleEngineFormDialog = ({
       payload.code = String(payload.code).toUpperCase();
     }
 
+    if (blocked) return;
+
     if (!initialRecord && positionOptions && position !== RULE_ENGINE_POSITION_END) {
       payload.insertAfterId = position;
     }
@@ -340,10 +360,10 @@ const RuleEngineFormDialog = ({
           value={resolveSelectValue(field, values)}
           onChange={(v) => setField(field.name, v === RULE_ENGINE_SELECT_NONE ? "" : v)}
           disabled={selectOptionsLoading}
-          // Native required blocks submit while a mandatory select is empty —
-          // without it the form posts and the API 400s (e.g. a container
-          // customs/lashing rate with no container type picked).
+          // Mantine's Select is not a native input, so `required` only marks it
+          // visually — handleSubmit is what actually blocks an empty one.
           required={field.required}
+          error={fieldErrors[field.name] || undefined}
           data={options
             .filter((opt) => opt.value !== "")
             .map((opt) => ({