feat(auth): enhance login flow with notifications and path normalization

- add success notification on successful login
- show error notification with detailed message on login failure
- normalize API paths to prevent double slashes and trailing slashes
- redirect to login page only if not on login request or page

web/src/lib/api.ts

@@ -22,13 +22,33 @@ import type {
 } from "../types";
 
 function getApiBaseUrl(): string {
-  if (import.meta.env.VITE_API_URL) return import.meta.env.VITE_API_URL;
+  if (import.meta.env.VITE_API_URL) return import.meta.env.VITE_API_URL.replace(/\/+$/, "");
   const { hostname, protocol, port } = window.location;
   if (hostname === "localhost" || hostname === "127.0.0.1") return "http://localhost:8080";
-  return `${protocol}//${hostname}${port ? `:${port}` : ""}`;
+  return `${protocol}//${hostname}${port ? `:${port}` : ""}`.replace(/\/+$/, "");
 }
 
 const API_BASE_URL = getApiBaseUrl();
+const LOGIN_API_PATH = "/api/v1/auth/login";
+const LOGIN_UI_PATH = "/ui/login";
+
+function normalizePath(path: string): string {
+  const collapsed = path.replace(/\/{2,}/g, "/");
+  if (collapsed.length > 1 && collapsed.endsWith("/")) {
+    return collapsed.slice(0, -1);
+  }
+  return collapsed || "/";
+}
+
+function getNormalizedPathFromURL(input: string): string {
+  if (!input) return "/";
+  try {
+    return normalizePath(new URL(input, window.location.origin).pathname);
+  } catch {
+    const withoutQuery = input.split("?")[0]?.split("#")[0] || "/";
+    return normalizePath(withoutQuery);
+  }
+}
 
 function normalizeUser(raw: unknown): User | null {
   if (!raw || typeof raw !== "object") return null;
@@ -96,9 +116,17 @@ class ApiClient {
       (response) => response,
       (error: AxiosError) => {
         if (error.response?.status === 401) {
-          // Token expired or invalid, clear auth and redirect
-          this.clearAuth();
-          window.location.href = "/ui/login";
+          const requestPath = getNormalizedPathFromURL(error.config?.url || "");
+          const currentPath = normalizePath(window.location.pathname);
+          const isLoginRequest = requestPath === LOGIN_API_PATH;
+          const isLoginPage = currentPath === LOGIN_UI_PATH;
+
+          // Keep failed login attempts on the same page.
+          if (!isLoginRequest && !isLoginPage) {
+            // Token expired or invalid, clear auth and redirect.
+            this.clearAuth();
+            window.location.href = LOGIN_UI_PATH;
+          }
         }
         return Promise.reject(error);
       },
@@ -122,7 +150,7 @@ class ApiClient {
   // Auth endpoints
   async login(credentials: LoginRequest): Promise<LoginResponse> {
     const { data } = await this.client.post<LoginResponse>(
-      "/api/v1/auth/login",
+      LOGIN_API_PATH,
       credentials,
     );
     if (data.token) {

web/src/pages/LoginPage.tsx

@@ -13,6 +13,7 @@ import {
   Center,
   Box
 } from '@mantine/core';
+import { notifications } from '@mantine/notifications';
 import { IconAlertCircle, IconBrandWhatsapp } from '@tabler/icons-react';
 import { useAuthStore } from '../stores/authStore';
 
@@ -28,10 +29,24 @@ export default function LoginPage() {
 
     try {
       await login(username, password);
+      notifications.show({
+        title: 'Login successful',
+        message: 'Welcome back!',
+        color: 'green',
+      });
       navigate('/');
-    } catch (err) {
-      // Error is handled in the store
-      console.error('Login failed:', err);
+    } catch (err: any) {
+      const responseData = err?.response?.data;
+      const notificationMessage =
+        responseData?.message ||
+        (typeof responseData === 'string' ? responseData.trim() : '') ||
+        'Invalid username or password';
+
+      notifications.show({
+        title: 'Login failed',
+        message: notificationMessage,
+        color: 'red',
+      });
     }
   };