improvement: error handeling structure changed and unified all across the app. user no longer sees inappropriate messages.

frontend/src/lib/api/client.ts

@@ -88,13 +88,34 @@ apiClient.interceptors.response.use(
       }
     }
 
+    const responseData = error.response?.data as
+      | { success?: false; error?: { code?: string; statusCode?: number; details?: ApiError['details'] } }
+      | { message?: string | string[] }
+      | undefined;
+
+    if (responseData && 'error' in responseData && responseData.error?.code) {
+      const apiError: ApiError = {
+        statusCode: responseData.error.statusCode ?? error.response?.status ?? 500,
+        code: responseData.error.code,
+        details: responseData.error.details,
+      };
+      return Promise.reject(apiError);
+    }
+
     const apiError: ApiError = {
       statusCode: error.response?.status || 500,
-      message:
-        (error.response?.data as any)?.message ||
-        error.message ||
-        'An unexpected error occurred',
-      error: (error.response?.data as any)?.error,
+      code:
+        error.response?.status === 401
+          ? 'AUTH_UNAUTHORIZED'
+          : error.response?.status === 403
+            ? 'PERMISSION_DENIED'
+            : error.response?.status === 404
+              ? 'NOT_FOUND'
+              : error.response?.status === 409
+                ? 'CONFLICT'
+                : (error.response?.status ?? 500) >= 500
+                  ? 'INTERNAL_ERROR'
+                  : 'BAD_REQUEST',
     };
 
     return Promise.reject(apiError);

frontend/src/lib/hooks/useAuth.tsx

@@ -16,6 +16,21 @@ import {
   rememberAccessTokenExpiresAt,
   startProactiveSessionRefresh,
 } from '@/lib/auth/proactiveRefresh';
+import { asApiError, legacyStatusCode, type ApiError } from '@/types/api';
+
+function toApiError(err: unknown): ApiError {
+  return (
+    asApiError(err) ?? {
+      statusCode: legacyStatusCode(err) ?? 500,
+      code:
+        legacyStatusCode(err) === 401
+          ? 'AUTH_UNAUTHORIZED'
+          : legacyStatusCode(err) === 403
+            ? 'PERMISSION_DENIED'
+            : 'INTERNAL_ERROR',
+    }
+  );
+}
 
 interface AuthContextType {
   user: User | null;
@@ -23,7 +38,7 @@ interface AuthContextType {
   currentOrganization: Organization | null;
   isLoading: boolean;
   isAuthReady: boolean;
-  error: string | null;
+  apiError: ApiError | null;
   registerTrial: (
     email: string,
     password: string,
@@ -56,7 +71,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
   const [currentOrganization, setCurrentOrganization] = useState<Organization | null>(null);
   const [isLoading, setIsLoading] = useState(false);
   const [isAuthReady, setIsAuthReady] = useState(false); // ✅ KEY FIX
-  const [error, setError] = useState<string | null>(null);
+  const [apiError, setApiError] = useState<ApiError | null>(null);
 
   const router = useRouter();
 
@@ -135,9 +150,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
         }
       }
     } catch (err: unknown) {
-      const status =
-        (err as { statusCode?: number })?.statusCode ??
-        (err as { response?: { status?: number } })?.response?.status;
+      const status = legacyStatusCode(err);
 
       // Access token may have expired while refresh cookie is still valid (e.g. JWT_EXPIRES_IN=15m).
       if (status === 401) {
@@ -251,7 +264,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
   ) => {
     try {
       setIsLoading(true);
-      setError(null);
+      setApiError(null);
 
       const response = await authApi.registerTrial({
         email,
@@ -282,7 +295,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       }
 
     } catch (err: any) {
-      setError(err.message || t('errorRegistrationFailed'));
+      setApiError(toApiError(err));
       throw err;
     } finally {
       setIsLoading(false);
@@ -297,7 +310,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
   ) => {
     try {
       setIsLoading(true);
-      setError(null);
+      setApiError(null);
 
       const response = await authApi.login({ email, password, rememberMe });
 
@@ -325,7 +338,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       }
 
     } catch (err: any) {
-      setError(err.message || t('errorLoginFailed'));
+      setApiError(toApiError(err));
       throw err;
     } finally {
       setIsLoading(false);
@@ -348,7 +361,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       setUser(null);
       setOrganizations([]);
       setCurrentOrganization(null);
-      setError(null);
+      setApiError(null);
       clearAccessTokenExpiresAt();
       setIsAuthReady(true);
       router.replace('/');
@@ -387,7 +400,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       }
 
     } catch (err: any) {
-      setError(err.message);
+      setApiError(toApiError(err));
       throw err;
     } finally {
       setIsLoading(false);
@@ -402,7 +415,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
   ) => {
     try {
       setIsLoading(true);
-      setError(null);
+      setApiError(null);
 
       const createResponse = await authApi.createOrganization({
         organizationName,
@@ -420,7 +433,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
 
       return createResponse.data.organization.id as string;
     } catch (err: any) {
-      setError(err.message || t('errorCreateOrganization'));
+      setApiError(toApiError(err));
       throw err;
     } finally {
       setIsLoading(false);
@@ -431,7 +444,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     await checkAuth();
   }, [checkAuth]);
 
-  const clearError = useCallback(() => setError(null), []);
+  const clearError = useCallback(() => setApiError(null), []);
 
   const setUserLanguage = useCallback((language: string) => {
     const normalized = isAppLocale(language) ? language : 'en';
@@ -445,7 +458,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       currentOrganization,
       isLoading,
       isAuthReady,
-      error,
+      apiError,
       registerTrial,
       login,
       logout,
@@ -461,7 +474,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       currentOrganization,
       isLoading,
       isAuthReady,
-      error,
+      apiError,
       registerTrial,
       login,
       logout,