diff --git a/reserva-mesa-dashboard/app/(auth)/login/page.tsx b/reserva-mesa-dashboard/app/(auth)/login/page.tsx
index 73c8870..9f94d84 100644
--- a/reserva-mesa-dashboard/app/(auth)/login/page.tsx
+++ b/reserva-mesa-dashboard/app/(auth)/login/page.tsx
@@ -23,11 +23,51 @@ export default function LoginPage() {
     setLoading(true);
 
     try {
-      await signInWithEmailAndPassword(auth, email, password);
+      const userCredential = await signInWithEmailAndPassword(auth, email, password);
+      
+      // Verify the user has a restaurant record before redirecting
+      if (!userCredential.user?.email) {
+        setError("Erro: Utilizador sem email válido.");
+        return;
+      }
+      
+      // Success — redirect to dashboard
       router.push("/");
     } catch (err: any) {
-      console.error(err);
-      setError("Credenciais inválidas. Verifique o seu email e palavra-passe.");
+      console.error("[Login Error]", err.code, err.message);
+      
+      // Map Firebase Auth error codes to user-friendly messages in Portuguese
+      switch (err.code) {
+        case "auth/user-not-found":
+          setError("Esta conta não existe. Verifique o email ou registe-se.");
+          break;
+        case "auth/wrong-password":
+          setError("Palavra-passe incorrecta. Tente novamente.");
+          break;
+        case "auth/invalid-email":
+          setError("Email inválido. Verifique o formato do email.");
+          break;
+        case "auth/invalid-credential":
+          setError("Credenciais inválidas. Verifique o email e a palavra-passe.");
+          break;
+        case "auth/too-many-requests":
+          setError("Demasiadas tentativas falhadas. Aguarde alguns minutos e tente novamente.");
+          break;
+        case "auth/invalid-verification-id":
+          setError("Sessão expirada. Por favor, recarregue a página e tente novamente.");
+          break;
+        case "auth/network-request-failed":
+          setError("Erro de conexão. Verifique a sua ligação à internet.");
+          break;
+        case "auth/weak-password":
+          setError("A palavra-passe é demasiado curta. Deve ter pelo menos 6 caracteres.");
+          break;
+        case "auth/popup-closed-by-user":
+          // User closed the popup — no error needed
+          break;
+        default:
+          setError("Erro ao entrar. Verifique as suas credenciais e tente novamente.");
+      }
     } finally {
       setLoading(false);
     }
diff --git a/reserva-mesa-dashboard/app/(auth)/register/page.tsx b/reserva-mesa-dashboard/app/(auth)/register/page.tsx
index 402df26..73ae056 100644
--- a/reserva-mesa-dashboard/app/(auth)/register/page.tsx
+++ b/reserva-mesa-dashboard/app/(auth)/register/page.tsx
@@ -37,6 +37,23 @@ export default function RegisterPage() {
     setError("");
     setLoading(true);
 
+    // Validate inputs before attempting registration
+    if (!formData.email || !formData.email.includes("@")) {
+      setError("Por favor, insira um email válido.");
+      setLoading(false);
+      return;
+    }
+    if (formData.password.length < 6) {
+      setError("A palavra-passe deve ter pelo menos 6 caracteres.");
+      setLoading(false);
+      return;
+    }
+    if (!formData.establishmentName.trim()) {
+      setError("Por favor, insira o nome do restaurante.");
+      setLoading(false);
+      return;
+    }
+
     try {
       // 1. Criar utilizador na Firebase Auth
       const userCredential = await createUserWithEmailAndPassword(auth, formData.email, formData.password);
@@ -62,10 +79,37 @@ export default function RegisterPage() {
       // 3. Gravar na Realtime Database em /Restaurantes
       await set(ref(db, `Restaurantes/${documentId}`), payload);
 
+      // 4. Success — redirect to dashboard
       router.push("/");
     } catch (err: any) {
-      console.error(err);
-      setError(err.message || "Ocorreu um erro ao registar o restaurante.");
+      console.error("[Register Error]", err.code, err.message);
+      
+      // Map Firebase Auth error codes to user-friendly messages in Portuguese
+      switch (err.code) {
+        case "auth/email-already-in-use":
+          setError("Este email já está registado. Tente fazer login.");
+          break;
+        case "auth/weak-password":
+          setError("A palavra-passe deve ter pelo menos 6 caracteres.");
+          break;
+        case "auth/invalid-email":
+          setError("Email inválido. Verifique o formato do email.");
+          break;
+        case "auth/operation-not-allowed":
+          setError("Registo de contas está desactivado. Contacte o suporte.");
+          break;
+        case "auth/network-request-failed":
+          setError("Erro de conexão. Verifique a sua ligação à internet.");
+          break;
+        case "auth/too-many-requests":
+          setError("Demasiadas tentativas. Aguarde alguns minutos e tente novamente.");
+          break;
+        case "auth/invalid-credential":
+          setError("Credenciais inválidas.");
+          break;
+        default:
+          setError(`Erro ao criar conta: ${err.message || "Tente novamente."}`);
+      }
     } finally {
       setLoading(false);
     }
diff --git a/reserva-mesa-dashboard/app/(dashboard)/page.tsx b/reserva-mesa-dashboard/app/(dashboard)/page.tsx
index 39f48d4..635970c 100644
--- a/reserva-mesa-dashboard/app/(dashboard)/page.tsx
+++ b/reserva-mesa-dashboard/app/(dashboard)/page.tsx
@@ -21,6 +21,15 @@ export default function DashboardHomePage() {
   const { mesas, loading: loadingMesas } = useMesas();
   const { staff } = useStaff();
 
+  // Guard against missing user data
+  if (!user) {
+    return (
+      <div className="flex items-center justify-center min-h-[60vh]">
+        <div className="text-primary font-display text-2xl animate-pulse">A carregar...</div>
+      </div>
+    );
+  }
+
   // 1. Calculate top stats
   const todayStr = new Date().toISOString().split('T')[0]; 
   const todayReservas = reservas.filter(r => r.data === todayStr || r.estado.startsWith("Confirmada"));
diff --git a/reserva-mesa-dashboard/components/auth/AuthGuard.tsx b/reserva-mesa-dashboard/components/auth/AuthGuard.tsx
index 1209e72..f6bd417 100644
--- a/reserva-mesa-dashboard/components/auth/AuthGuard.tsx
+++ b/reserva-mesa-dashboard/components/auth/AuthGuard.tsx
@@ -11,6 +11,7 @@ export default function AuthGuard({ children }: { children: React.ReactNode }) {
 
   useEffect(() => {
     if (!loading) {
+      // If user is not authenticated and not on a public page, redirect to login
       if (!user && !pathname.startsWith("/login") && !pathname.startsWith("/register")) {
         router.push("/login");
       }
@@ -25,8 +26,8 @@ export default function AuthGuard({ children }: { children: React.ReactNode }) {
     );
   }
 
-  // Se não estiver logado e não estiver numa rota pública, não renderiza nada 
-  // (o useEffect vai redirecionar)
+  // If not authenticated and not on a public page, don't render children
+  // (the useEffect will redirect)
   if (!user && !pathname.startsWith("/login") && !pathname.startsWith("/register")) {
     return null;
   }
diff --git a/reserva-mesa-dashboard/components/dashboard/NotificationMonitor.tsx b/reserva-mesa-dashboard/components/dashboard/NotificationMonitor.tsx
index da207e1..218378c 100644
--- a/reserva-mesa-dashboard/components/dashboard/NotificationMonitor.tsx
+++ b/reserva-mesa-dashboard/components/dashboard/NotificationMonitor.tsx
@@ -20,12 +20,17 @@ export function NotificationMonitor() {
     // Primeiro, marcamos todas as reservas existentes como "vistas"
     // para não disparar notificações para o passado
     const loadExisting = async () => {
-      const snapshot = await get(reservasRef);
-      if (snapshot.exists()) {
-        const data = snapshot.val();
-        Object.keys(data).forEach(id => seenReservas.current.add(id));
+      try {
+        const snapshot = await get(reservasRef);
+        if (snapshot.exists()) {
+          const data = snapshot.val();
+          Object.keys(data).forEach(id => seenReservas.current.add(id));
+        }
+      } catch (error) {
+        console.error("[NotificationMonitor] Error loading existing reservas:", error);
+      } finally {
+        isInitialLoad.current = false;
       }
-      isInitialLoad.current = false;
     };
 
     loadExisting();
@@ -40,9 +45,13 @@ export function NotificationMonitor() {
       // Se ainda estivermos no load inicial (do get), ignoramos o toast
       if (isInitialLoad.current) return;
 
-      const data = snapshot.val();
-      if (data.restauranteEmail === user.email && data.estado === "Pendente") {
-        toast(`Nova reserva recebida de ${data.clienteEmail}!`, "info");
+      try {
+        const data = snapshot.val();
+        if (data?.restauranteEmail === user.email && data?.estado === "Pendente") {
+          toast(`Nova reserva recebida de ${data?.clienteEmail || "cliente"}!`, "info");
+        }
+      } catch (error) {
+        console.error("[NotificationMonitor] Error processing new reserva:", error);
       }
     });
 
diff --git a/reserva-mesa-dashboard/contexts/AuthContext.tsx b/reserva-mesa-dashboard/contexts/AuthContext.tsx
index cdba70d..9416145 100644
--- a/reserva-mesa-dashboard/contexts/AuthContext.tsx
+++ b/reserva-mesa-dashboard/contexts/AuthContext.tsx
@@ -33,34 +33,106 @@ export const AuthProvider = ({ children }: { children: React.ReactNode }) => {
     return email.replace(/\./g, "_").replace(/@/g, "_at_");
   };
 
+  // Search for user by UID across all Restaurantes documents
+  const findUserByUid = async (uid: string, currentUser: FirebaseUser): Promise<RestaurantUser | null> => {
+    try {
+      const restaurantsRef = ref(db, "Restaurantes");
+      const snapshot = await get(restaurantsRef);
+      if (!snapshot.exists()) return null;
+      
+      const data = snapshot.val();
+      for (const key of Object.keys(data)) {
+        const item = data[key];
+        if (item?.uid === uid) {
+          return { ...item, email: item.email || currentUser.email } as RestaurantUser;
+        }
+      }
+    } catch (error) {
+      console.error("[Auth] Error searching by UID:", error);
+    }
+    return null;
+  };
+
+  // Search for user by email across all Restaurantes documents
+  const findUserByEmail = async (email: string): Promise<RestaurantUser | null> => {
+    try {
+      const restaurantsRef = ref(db, "Restaurantes");
+      const snapshot = await get(restaurantsRef);
+      if (!snapshot.exists()) return null;
+      
+      const data = snapshot.val();
+      for (const key of Object.keys(data)) {
+        const item = data[key];
+        if (item?.email === email || item?.establishmentEmail === email || item?.ownerEmail === email) {
+          return { ...item, email: item.email || email } as RestaurantUser;
+        }
+      }
+    } catch (error) {
+      console.error("[Auth] Error searching by email:", error);
+    }
+    return null;
+  };
+
   useEffect(() => {
     const unsubscribe = onAuthStateChanged(auth, async (currentUser) => {
       try {
         if (currentUser && currentUser.email) {
           setFirebaseUser(currentUser);
+          
+          let data: RestaurantUser | null = null;
+          
+          // Strategy 1: Try building document ID from email (website format)
           const docId = buildDocumentId(currentUser.email);
           const userRef = ref(db, `Restaurantes/${docId}`);
-          const snapshot = await get(userRef);
+          let snapshot = await get(userRef);
           
           if (snapshot.exists()) {
-            const data = snapshot.val() as RestaurantUser;
+            data = snapshot.val() as RestaurantUser;
+          }
+          
+          // Strategy 2: Try with original email as document ID (Android format)
+          if (!data) {
+            const originalRef = ref(db, `Restaurantes/${currentUser.email}`);
+            snapshot = await get(originalRef);
+            if (snapshot.exists()) {
+              data = snapshot.val() as RestaurantUser;
+            }
+          }
+          
+          // Strategy 3: Search all Restaurantes documents by UID
+          if (!data && currentUser.uid) {
+            data = await findUserByUid(currentUser.uid, currentUser);
+          }
+          
+          // Strategy 4: Search all Restaurantes documents by email
+          if (!data) {
+            data = await findUserByEmail(currentUser.email);
+          }
+          
+          if (data) {
             if (data.accountType === "ESTABELECIMENTO") {
               setUser(data);
             } else {
-              console.warn("User is not a restaurant");
+              console.warn("[Auth] User is not a restaurant account type:", data.accountType);
               setUser(null);
               await signOut(auth);
             }
           } else {
-            console.warn("User record not found in Restaurantes");
+            // User exists in Auth but not in database — possible orphaned account
+            console.warn("[Auth] User record not found in Restaurantes for:", currentUser.email);
+            console.warn("[Auth] UID:", currentUser.uid);
             setUser(null);
           }
         } else {
+          // No Firebase user — clear state
           setFirebaseUser(null);
           setUser(null);
         }
       } catch (error) {
-        console.error("Auth initialization error:", error);
+        console.error("[Auth] Error in onAuthStateChanged:", error);
+        // On error, clear user state to prevent broken state
+        setUser(null);
+        setFirebaseUser(null);
       } finally {
         setLoading(false);
       }
diff --git a/reserva-mesa-dashboard/hooks/useMesas.ts b/reserva-mesa-dashboard/hooks/useMesas.ts
index 1851552..93abdd6 100644
--- a/reserva-mesa-dashboard/hooks/useMesas.ts
+++ b/reserva-mesa-dashboard/hooks/useMesas.ts
@@ -17,26 +17,32 @@ export function useMesas() {
     const mesasRef = ref(db, "Mesas");
     
     const unsubscribe = onValue(mesasRef, (snapshot) => {
-      const data = snapshot.val();
-      const list: Mesa[] = [];
-      
-      if (data) {
-        Object.keys(data).forEach((key) => {
-          const item = data[key];
-          if (item.restauranteEmail === user.email) {
-            list.push({
-              id: key,
-              ...item
-            });
-          }
-        });
-      }
-      
-      // Sort by table number
-      list.sort((a, b) => a.numero - b.numero);
+      try {
+        const data = snapshot.val();
+        const list: Mesa[] = [];
+        
+        if (data) {
+          Object.keys(data).forEach((key) => {
+            const item = data[key];
+            if (item?.restauranteEmail === user.email) {
+              list.push({
+                id: key,
+                ...item
+              });
+            }
+          });
+        }
+        
+        // Sort by table number
+        list.sort((a, b) => a.numero - b.numero);
 
-      setMesas(list);
-      setLoading(false);
+        setMesas(list);
+      } catch (error) {
+        console.error("[useMesas] Error processing data:", error);
+        setMesas([]);
+      } finally {
+        setLoading(false);
+      }
     });
 
     return () => off(mesasRef, "value", unsubscribe);
diff --git a/reserva-mesa-dashboard/hooks/useReservas.ts b/reserva-mesa-dashboard/hooks/useReservas.ts
index 48a573a..0aeaf98 100644
--- a/reserva-mesa-dashboard/hooks/useReservas.ts
+++ b/reserva-mesa-dashboard/hooks/useReservas.ts
@@ -17,30 +17,36 @@ export function useReservas() {
     const reservasRef = ref(db, "reservas");
     
     const unsubscribe = onValue(reservasRef, (snapshot) => {
-      const data = snapshot.val();
-      const list: Reserva[] = [];
-      
-      if (data) {
-        Object.keys(data).forEach((key) => {
-          const item = data[key];
-          if (item.restauranteEmail === user.email) {
-            list.push({
-              id: key,
-              ...item
-            });
-          }
+      try {
+        const data = snapshot.val();
+        const list: Reserva[] = [];
+        
+        if (data) {
+          Object.keys(data).forEach((key) => {
+            const item = data[key];
+            if (item?.restauranteEmail === user.email) {
+              list.push({
+                id: key,
+                ...item
+              });
+            }
+          });
+        }
+        
+        // Sort by date and time (newest first for management)
+        list.sort((a, b) => {
+          const dateA = new Date(`${a.data.replace(/-/g, "/")} ${a.hora}`);
+          const dateB = new Date(`${b.data.replace(/-/g, "/")} ${b.hora}`);
+          return dateB.getTime() - dateA.getTime();
         });
-      }
-      
-      // Sort by date and time (newest first for management)
-      list.sort((a, b) => {
-        const dateA = new Date(`${a.data.replace(/-/g, "/")} ${a.hora}`);
-        const dateB = new Date(`${b.data.replace(/-/g, "/")} ${b.hora}`);
-        return dateB.getTime() - dateA.getTime();
-      });
 
-      setReservas(list);
-      setLoading(false);
+        setReservas(list);
+      } catch (error) {
+        console.error("[useReservas] Error processing data:", error);
+        setReservas([]);
+      } finally {
+        setLoading(false);
+      }
     });
 
     return () => off(reservasRef, "value", unsubscribe);
diff --git a/reserva-mesa-dashboard/hooks/useStaff.ts b/reserva-mesa-dashboard/hooks/useStaff.ts
index 1bb327d..864cf54 100644
--- a/reserva-mesa-dashboard/hooks/useStaff.ts
+++ b/reserva-mesa-dashboard/hooks/useStaff.ts
@@ -17,23 +17,29 @@ export function useStaff() {
     const staffRef = ref(db, "Staff");
     
     const unsubscribe = onValue(staffRef, (snapshot) => {
-      const data = snapshot.val();
-      const list: Staff[] = [];
-      
-      if (data) {
-        Object.keys(data).forEach((key) => {
-          const item = data[key];
-          if (item.restauranteEmail === user.email) {
-            list.push({
-              id: key,
-              ...item
-            });
-          }
-        });
+      try {
+        const data = snapshot.val();
+        const list: Staff[] = [];
+        
+        if (data) {
+          Object.keys(data).forEach((key) => {
+            const item = data[key];
+            if (item?.restauranteEmail === user.email) {
+              list.push({
+                id: key,
+                ...item
+              });
+            }
+          });
+        }
+        
+        setStaff(list);
+      } catch (error) {
+        console.error("[useStaff] Error processing data:", error);
+        setStaff([]);
+      } finally {
+        setLoading(false);
       }
-      
-      setStaff(list);
-      setLoading(false);
     });
 
     return () => off(staffRef, "value", unsubscribe);
diff --git a/reserva-mesa-dashboard/lib/firebase.ts b/reserva-mesa-dashboard/lib/firebase.ts
index f743d8f..4ee3470 100644
--- a/reserva-mesa-dashboard/lib/firebase.ts
+++ b/reserva-mesa-dashboard/lib/firebase.ts
@@ -1,22 +1,53 @@
-import { initializeApp, getApps } from "firebase/app";
+import { initializeApp, getApps, getApp } from "firebase/app";
 import { getAuth } from "firebase/auth";
 import { getDatabase } from "firebase/database";
 
 // As variáveis de ambiente devem ser configuradas no Vercel e no ficheiro .env.local
 const firebaseConfig = {
-  apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY || "AIzaSyCPz7Pd3tJj3QkF7fV_vudCJythNsyR57k",
-  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN || "namesa-429c1.firebaseapp.com",
-  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID || "namesa-429c1",
-  storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET || "namesa-429c1.firebasestorage.app",
-  messagingSenderId: process.env.NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID || "476421715902",
-  appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID || "1:476421715902:web:placeholder", // placeholder needed for web client SDK
-  // Nota importante: Como verificado na codebase Android, 
-  // O ReservaMesa usa Realtime Database e não Firestore.
+  apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY,
+  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
+  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
+  storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
+  messagingSenderId: process.env.NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID,
+  appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID,
   databaseURL: process.env.NEXT_PUBLIC_FIREBASE_DATABASE_URL || "https://namesa-429c1-default-rtdb.firebaseio.com"
 };
 
-// Initialize Firebase only if there are no apps initialized yet
-const app = getApps().length === 0 ? initializeApp(firebaseConfig) : getApps()[0];
+// Validate that all required environment variables are present
+const requiredEnvVars = [
+  "NEXT_PUBLIC_FIREBASE_API_KEY",
+  "NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN",
+  "NEXT_PUBLIC_FIREBASE_PROJECT_ID",
+  "NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET",
+  "NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID",
+  "NEXT_PUBLIC_FIREBASE_APP_ID",
+];
+
+const missingVars = requiredEnvVars.filter(
+  (key) => !process.env[key]
+);
+
+if (missingVars.length > 0) {
+  console.error(
+    "[Firebase] Missing environment variables:",
+    missingVars.join(", "),
+    "\nPlease ensure all Firebase environment variables are set in .env.local or your hosting platform."
+  );
+}
+
+// Initialize Firebase only once — prevents duplicate app errors in development (HMR) and SSR
+let app;
+try {
+  app = getApps().length === 0 ? initializeApp(firebaseConfig) : getApp();
+} catch (error: any) {
+  if (error?.code === "app/duplicate-app") {
+    app = getApp();
+  } else {
+    throw new Error(
+      `[Firebase] Failed to initialize: ${error?.message || "Unknown error"}. Check your environment variables.`
+    );
+  }
+}
 
 export const auth = getAuth(app);
 export const db = getDatabase(app);
diff --git a/reserva-mesa-dashboard/package-lock.json b/reserva-mesa-dashboard/package-lock.json
index 2caa625..d4764ed 100644
--- a/reserva-mesa-dashboard/package-lock.json
+++ b/reserva-mesa-dashboard/package-lock.json
@@ -14,7 +14,7 @@
         "class-variance-authority": "^0.7.0",
         "clsx": "^2.1.1",
         "date-fns": "^3.6.0",
-        "firebase": "^10.12.0",
+        "firebase": "^10.14.1",
         "framer-motion": "^11.1.7",
         "lucide-react": "^0.378.0",
         "next": "14.2.3",
diff --git a/reserva-mesa-dashboard/package.json b/reserva-mesa-dashboard/package.json
index 35f89a5..6f16048 100644
--- a/reserva-mesa-dashboard/package.json
+++ b/reserva-mesa-dashboard/package.json
@@ -10,10 +10,12 @@
   },
   "dependencies": {
     "@hookform/resolvers": "^3.3.4",
+    "@radix-ui/react-label": "^2.0.2",
+    "@radix-ui/react-slot": "^1.0.2",
     "class-variance-authority": "^0.7.0",
     "clsx": "^2.1.1",
     "date-fns": "^3.6.0",
-    "firebase": "^10.12.0",
+    "firebase": "^10.14.1",
     "framer-motion": "^11.1.7",
     "lucide-react": "^0.378.0",
     "next": "14.2.3",
@@ -23,8 +25,6 @@
     "recharts": "^2.12.7",
     "tailwind-merge": "^2.3.0",
     "tailwindcss-animate": "^1.0.7",
-    "@radix-ui/react-label": "^2.0.2",
-    "@radix-ui/react-slot": "^1.0.2",
     "zod": "^3.23.6"
   },
   "devDependencies": {