diff --git a/backend/README.md b/backend/README.md
index 940937f..9d3d3b8 100644
--- a/backend/README.md
+++ b/backend/README.md
@@ -1,4 +1,5 @@
-Backend startup quickstarat:
+Backend startup quickstart:
+
 ----------------------------->  BEST
 ## 1. brew services start postgresql@15
 
diff --git a/backend/infra/migrations/010_add_unique_email_index.sql b/backend/infra/migrations/010_add_unique_email_index.sql
new file mode 100644
index 0000000..a51149e
--- /dev/null
+++ b/backend/infra/migrations/010_add_unique_email_index.sql
@@ -0,0 +1,20 @@
+-- Migration 010: enforce unique emails in users
+-- Matches runtime expectation for idx_users_email_unique.
+
+BEGIN;
+
+DO $$
+BEGIN
+  IF EXISTS (
+    SELECT 1
+    FROM users
+    GROUP BY email
+    HAVING COUNT(*) > 1
+  ) THEN
+    RAISE EXCEPTION 'Cannot create unique index idx_users_email_unique: duplicate emails exist in users';
+  END IF;
+END $$;
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_users_email_unique ON users(email);
+
+COMMIT;
diff --git a/backend/internal/models/user.go b/backend/internal/models/user.go
index 1481c68..9f5b4af 100644
--- a/backend/internal/models/user.go
+++ b/backend/internal/models/user.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 
 	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
@@ -37,10 +38,55 @@ func scanUser(row pgx.Row) (*domain.User, error) {
 	return &u, nil
 }
 
+func (m *UserModel) getByFirebaseUID(ctx context.Context, firebaseUID string) (*domain.User, error) {
+	row := m.pool.QueryRow(ctx,
+		`SELECT `+userColumns+` FROM users WHERE firebase_uid = $1`,
+		firebaseUID,
+	)
+	return scanUser(row)
+}
+
+func (m *UserModel) getByEmail(ctx context.Context, email string) (*domain.User, error) {
+	row := m.pool.QueryRow(ctx,
+		`SELECT `+userColumns+` FROM users WHERE email = $1`,
+		email,
+	)
+	return scanUser(row)
+}
+
+func isUniqueViolation(err error) bool {
+	var pgErr *pgconn.PgError
+	if errors.As(err, &pgErr) {
+		return pgErr.Code == "23505"
+	}
+	return false
+}
+
 // FindOrCreateByFirebaseUID returns the local user for a Firebase UID,
-// creating one if it doesn't exist yet. On conflict (returning user) the
-// updated_at timestamp is refreshed.
+// creating one if it doesn't exist yet.
+//
+// For onboarding races or legacy duplicate-identity states, this method
+// gracefully falls back to an existing row by email instead of failing
+// with a unique-email violation.
 func (m *UserModel) FindOrCreateByFirebaseUID(ctx context.Context, firebaseUID, email string) (*domain.User, error) {
+	existingByUID, err := m.getByFirebaseUID(ctx, firebaseUID)
+	if err != nil {
+		return nil, err
+	}
+	if existingByUID != nil {
+		return existingByUID, nil
+	}
+
+	if email != "" {
+		existingByEmail, err := m.getByEmail(ctx, email)
+		if err != nil {
+			return nil, err
+		}
+		if existingByEmail != nil {
+			return existingByEmail, nil
+		}
+	}
+
 	row := m.pool.QueryRow(ctx,
 		`INSERT INTO users (firebase_uid, email)
 		 VALUES ($1, $2)
@@ -48,7 +94,33 @@ func (m *UserModel) FindOrCreateByFirebaseUID(ctx context.Context, firebaseUID,
 		 RETURNING `+userColumns,
 		firebaseUID, email,
 	)
-	return scanUser(row)
+	user, err := scanUser(row)
+	if err == nil {
+		return user, nil
+	}
+
+	// If a concurrent request inserted by email or firebase_uid first,
+	// read the existing record and continue without surfacing a 500.
+	if isUniqueViolation(err) {
+		existingByUID, readErr := m.getByFirebaseUID(ctx, firebaseUID)
+		if readErr != nil {
+			return nil, readErr
+		}
+		if existingByUID != nil {
+			return existingByUID, nil
+		}
+		if email != "" {
+			existingByEmail, readErr := m.getByEmail(ctx, email)
+			if readErr != nil {
+				return nil, readErr
+			}
+			if existingByEmail != nil {
+				return existingByEmail, nil
+			}
+		}
+	}
+
+	return nil, err
 }
 
 func (m *UserModel) GetByID(ctx context.Context, id string) (*domain.User, error) {
diff --git a/frontend/src/App.jsx b/frontend/src/App.jsx
index 014f142..a99c4ac 100644
--- a/frontend/src/App.jsx
+++ b/frontend/src/App.jsx
@@ -11,7 +11,9 @@ import AlertHistory from "./pages/alertHistory/AlertHistory";
 import Account from "./pages/user_account/Account";
 
 export default function App() {
-  const { currentUser, isSubscribed } = useAuth();
+  const { currentUser, isSubscribed, loading } = useAuth();
+
+  if (loading) return null;
 
   if (!currentUser) {
     return (
diff --git a/frontend/src/contexts/AuthContext.jsx b/frontend/src/contexts/AuthContext.jsx
index 0413bd3..cb375e6 100644
--- a/frontend/src/contexts/AuthContext.jsx
+++ b/frontend/src/contexts/AuthContext.jsx
@@ -1,140 +1,94 @@
-/**
- * AuthContext - Firebase Authentication State Management
- *
- * Provides authentication state, tier info, and methods throughout the app
- */
-
-import { createContext, useContext, useEffect, useState, useCallback } from "react";
+import { createContext, useContext, useState, useEffect, useCallback } from "react";
 import {
-    createUserWithEmailAndPassword,
-    signInWithEmailAndPassword,
-    signOut,
-    onAuthStateChanged,
+  onAuthStateChanged,
+  signInWithEmailAndPassword,
+  createUserWithEmailAndPassword,
+  signOut,
 } from "firebase/auth";
 import { auth } from "../firebase/config";
 import { getAccount } from "../api/account";
 
-const AuthContext = createContext();
+const AuthContext = createContext(undefined);
 
 const DEFAULT_TIER_LIMITS = {
-    max_addresses: 1,
-    max_alert_types: 1,
-    allowed_channels: ["email"],
+  max_addresses: 1,
+  max_alert_types: 1,
+  allowed_channels: ["email"],
 };
 
-/**
- * Hook to access auth context
- * @returns {Object} Auth context value
- */
-export function useAuth() {
-    const context = useContext(AuthContext);
-    if (!context) {
-        throw new Error("useAuth must be used within AuthProvider");
-    }
-    return context;
-}
-
-/**
- * AuthProvider - Wraps app and provides auth state + tier info
- */
 export function AuthProvider({ children }) {
-    const [currentUser, setCurrentUser] = useState(null);
-    const [loading, setLoading] = useState(true);
-    const [error, setError] = useState(null);
+  const [currentUser, setCurrentUser] = useState(null);
+  const [userTier, setUserTier] = useState("free");
+  const [tierLimits, setTierLimits] = useState(DEFAULT_TIER_LIMITS);
+  const [isSubscribed, setIsSubscribed] = useState(false);
+  const [loading, setLoading] = useState(true);
 
-    const [userTier, setUserTier] = useState("free");
-    const [tierLimits, setTierLimits] = useState(DEFAULT_TIER_LIMITS);
-    const [addressCount, setAddressCount] = useState(0);
-    const [subscriptionStatus, setSubscriptionStatus] = useState("none");
-
-    const refreshAccount = useCallback(async () => {
-        try {
-            const data = await getAccount();
-            setUserTier(data.subscription_tier || "free");
-            setTierLimits(data.tier_limits || DEFAULT_TIER_LIMITS);
-            setAddressCount(data.address_count || 0);
-            setSubscriptionStatus(data.subscription_status || "none");
-        } catch {
-            // account fetch can fail during onboarding before subscription is active
-        }
-    }, []);
-
-    async function signup(email, password) {
-        try {
-            setError(null);
-            const result = await createUserWithEmailAndPassword(
-                auth,
-                email,
-                password,
-            );
-            return result.user;
-        } catch (err) {
-            setError(err.message);
-            throw err;
-        }
+  const fetchAccount = useCallback(async () => {
+    try {
+      const data = await getAccount();
+      setUserTier(data.subscription_tier || "free");
+      setTierLimits(data.tier_limits || DEFAULT_TIER_LIMITS);
+      setIsSubscribed(
+        data.subscription_status === "active" ||
+          data.subscription_status === "trialing",
+      );
+    } catch {
+      setUserTier("free");
+      setTierLimits(DEFAULT_TIER_LIMITS);
+      setIsSubscribed(false);
     }
+  }, []);
 
-    async function login(email, password) {
-        try {
-            setError(null);
-            const result = await signInWithEmailAndPassword(
-                auth,
-                email,
-                password,
-            );
-            return result.user;
-        } catch (err) {
-            setError(err.message);
-            throw err;
-        }
-    }
+  useEffect(() => {
+    const unsubscribe = onAuthStateChanged(auth, async (user) => {
+      setCurrentUser(user);
+      if (user) {
+        await fetchAccount();
+      } else {
+        setUserTier("free");
+        setTierLimits(DEFAULT_TIER_LIMITS);
+        setIsSubscribed(false);
+      }
+      setLoading(false);
+    });
+    return unsubscribe;
+  }, [fetchAccount]);
 
-    async function logout() {
-        try {
-            setError(null);
-            setUserTier("free");
-            setTierLimits(DEFAULT_TIER_LIMITS);
-            setAddressCount(0);
-            setSubscriptionStatus("none");
-            await signOut(auth);
-        } catch (err) {
-            setError(err.message);
-            throw err;
-        }
-    }
+  async function signup(email, password) {
+    const cred = await createUserWithEmailAndPassword(auth, email, password);
+    return cred.user;
+  }
 
-    useEffect(() => {
-        const unsubscribe = onAuthStateChanged(auth, (user) => {
-            setCurrentUser(user);
-            setLoading(false);
-            if (user) {
-                refreshAccount();
-            }
-        });
-        return unsubscribe;
-    }, [refreshAccount]);
+  async function login(email, password) {
+    const cred = await signInWithEmailAndPassword(auth, email, password);
+    return cred.user;
+  }
 
-    const isSubscribed =
-        subscriptionStatus === "active" || subscriptionStatus === "trialing";
+  async function logout() {
+    await signOut(auth);
+  }
 
-    const value = {
-        currentUser,
-        signup,
-        login,
-        logout,
-        error,
-        loading,
-        userTier,
-        tierLimits,
-        addressCount,
-        subscriptionStatus,
-        isSubscribed,
-        refreshAccount,
-    };
+  const value = {
+    currentUser,
+    userTier,
+    tierLimits,
+    isSubscribed,
+    loading,
+    signup,
+    login,
+    logout,
+    refreshAccount: fetchAccount,
+  };
 
-    return (
-        <AuthContext.Provider value={value}>
-            {!loading && children}
-        </AuthContext.Provider>
-    );
+  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
 }
+
+export function useAuth() {
+  const context = useContext(AuthContext);
+  if (context === undefined) {
+    throw new Error("useAuth must be used within an AuthProvider");
+  }
+  return context;
+}
+
+export default useAuth;
diff --git a/frontend/src/contexts/UserPropertiesContext.jsx b/frontend/src/contexts/UserPropertiesContext.jsx
new file mode 100644
index 0000000..0bb91a4
--- /dev/null
+++ b/frontend/src/contexts/UserPropertiesContext.jsx
@@ -0,0 +1,44 @@
+import { createContext, useReducer, useContext } from "react";
+
+const initialState = {
+  email: "",
+  password: "",
+};
+
+const ACTION_TYPES = {
+  SET_USER_PROPERTIES: "SET_USER_PROPERTIES",
+  CLEAR_USER_PROPERTIES: "CLEAR_USER_PROPERTIES",
+};
+
+function userPropertiesReducer(state, action) {
+  switch (action.type) {
+    case ACTION_TYPES.SET_USER_PROPERTIES:
+      return { ...state, ...action.payload };
+    case ACTION_TYPES.CLEAR_USER_PROPERTIES:
+      return { ...initialState };
+    default:
+      return state;
+  }
+}
+
+const UserPropertiesContext = createContext(undefined);
+
+export function UserPropertiesProvider({ children }) {
+  const [state, dispatch] = useReducer(userPropertiesReducer, initialState);
+
+  return (
+    <UserPropertiesContext.Provider value={{ state, dispatch, ACTION_TYPES }}>
+      {children}
+    </UserPropertiesContext.Provider>
+  );
+}
+
+export function useUserProperties() {
+  const context = useContext(UserPropertiesContext);
+  if (context === undefined) {
+    throw new Error(
+      "useUserProperties must be used within a UserPropertiesProvider",
+    );
+  }
+  return context;
+}
diff --git a/frontend/src/main.jsx b/frontend/src/main.jsx
index 00913df..6c791fd 100644
--- a/frontend/src/main.jsx
+++ b/frontend/src/main.jsx
@@ -2,15 +2,18 @@ import React from "react";
 import ReactDOM from "react-dom/client";
 import { BrowserRouter } from "react-router-dom";
 import { AuthProvider } from "./contexts/AuthContext";
+import { UserPropertiesProvider } from "./contexts/UserPropertiesContext";
 import App from "./App";
 import "./index.css";
 
 ReactDOM.createRoot(document.getElementById("root")).render(
     <React.StrictMode>
         <BrowserRouter>
-            <AuthProvider>
-                <App />
-            </AuthProvider>
+            <UserPropertiesProvider>
+                <AuthProvider>
+                    <App />
+                </AuthProvider>
+            </UserPropertiesProvider>
         </BrowserRouter>
     </React.StrictMode>,
 );
diff --git a/frontend/src/pages/subscribe/Subscribe.jsx b/frontend/src/pages/subscribe/Subscribe.jsx
index e776894..8ba7685 100644
--- a/frontend/src/pages/subscribe/Subscribe.jsx
+++ b/frontend/src/pages/subscribe/Subscribe.jsx
@@ -1,6 +1,7 @@
 import { useState } from "react";
 import { useNavigate, useSearchParams } from "react-router-dom";
 import { useAuth } from "../../contexts/AuthContext";
+import { useUserProperties } from "../../contexts/UserPropertiesContext";
 import {
   createCheckoutSession,
   activateFreeTier,
@@ -21,7 +22,7 @@ export default function Subscribe() {
   const success = queryParameters?.get("payment")
   const session_id = queryParameters?.get("session_id")
 
-  console.log('success, session_id_________________________------------>', success, session_id)
+  console.log('success, session_id ------>', success, session_id)
 
   function forward(success, session_id) {
     success && session_id ?