frontend/src/App.tsx

@@ -9,7 +9,7 @@ const cityImage = new URL('./assets/city-panorama.png', import.meta.url).href;
 const loginRoomImage = new URL('./assets/login-room.png', import.meta.url).href;
 const SMS_VERIFICATION_CODE = '123456';
 
-type View = 'home' | 'buy' | 'rent' | 'sell' | 'valuation' | 'priceHistory' | 'districtRanking' | 'negotiation' | 'comparison' | 'add' | 'services' | 'guides' | 'map' | 'login' | 'account' | 'accountMeetings' | 'accountListings' | 'accountSettings' | 'accountSecurity' | 'accountProfileEdit' | 'accountPublicProfile' | 'notifications' | 'favorites' | 'messages' | 'admin' | 'listingDetail';
+type View = 'home' | 'buy' | 'rent' | 'sell' | 'valuation' | 'priceHistory' | 'districtRanking' | 'negotiation' | 'comparison' | 'add' | 'services' | 'guides' | 'map' | 'login' | 'account' | 'accountPriceAlerts' | 'accountMeetings' | 'accountListings' | 'accountSettings' | 'accountSecurity' | 'accountProfileEdit' | 'accountPublicProfile' | 'notifications' | 'favorites' | 'messages' | 'admin' | 'listingDetail';
 
 type MessageThreadListing = {
   listingId: number;
@@ -109,7 +109,7 @@ type LiveListingSummary = ApiListingSummary & {
 const LIVE_LISTINGS_REFRESH_MS = 15000;
 
 const PROTECTED_VIEWS = new Set<View>([
-  'add', 'admin', 'account', 'accountMeetings', 'accountListings', 'accountSettings',
+  'add', 'admin', 'account', 'accountPriceAlerts', 'accountMeetings', 'accountListings', 'accountSettings',
   'accountSecurity', 'accountProfileEdit', 'accountPublicProfile', 'notifications', 'favorites', 'messages', 'comparison',
 ]);
 
@@ -362,6 +362,73 @@ type FavoriteListing = {
   badge: string;
 };
 
+type FavoritePriceAlertEvent = {
+  id: string;
+  listingId: number;
+  title: string;
+  location: string;
+  area: string;
+  previousPrice: number;
+  currentPrice: number;
+  changedAt: string;
+};
+
+type CityPriceAlertSubscription = {
+  key: string;
+  label: string;
+  city: string;
+  region: string;
+  propertyType: HistoryPropertyType;
+  marketType: HistoryMarketType;
+  createdAt: string;
+};
+
+const FAVORITE_PRICE_ALERTS_STORAGE_SUFFIX = 'favorite-price-alert-events';
+const FAVORITE_PRICE_SNAPSHOTS_STORAGE_SUFFIX = 'favorite-price-snapshots';
+const CITY_PRICE_ALERTS_STORAGE_SUFFIX = 'city-price-alert-subscriptions';
+const PRICE_ALERT_EVENTS_LIMIT = 40;
+
+function readUserJsonStorage<T>(user: AuthUser | null, suffix: string, fallback: T): T {
+  if (typeof window === 'undefined') {
+    return fallback;
+  }
+  try {
+    const raw = window.localStorage.getItem(accountStorageKey(suffix, user));
+    if (!raw) {
+      return fallback;
+    }
+    return JSON.parse(raw) as T;
+  } catch {
+    return fallback;
+  }
+}
+
+function writeUserJsonStorage<T>(user: AuthUser | null, suffix: string, value: T): void {
+  if (typeof window === 'undefined') {
+    return;
+  }
+  window.localStorage.setItem(accountStorageKey(suffix, user), JSON.stringify(value));
+}
+
+function mergePriceAlertEvents(
+  incoming: FavoritePriceAlertEvent[],
+  existing: FavoritePriceAlertEvent[],
+): FavoritePriceAlertEvent[] {
+  if (incoming.length === 0) {
+    return existing;
+  }
+
+  const known = new Set(existing.map((item) => item.id));
+  const uniqueIncoming = incoming.filter((item) => !known.has(item.id));
+  if (uniqueIncoming.length === 0) {
+    return existing;
+  }
+
+  return [...uniqueIncoming, ...existing]
+    .sort((left, right) => new Date(right.changedAt).getTime() - new Date(left.changedAt).getTime())
+    .slice(0, PRICE_ALERT_EVENTS_LIMIT);
+}
+
 const favoriteListings: FavoriteListing[] = [];
 
 function favoriteListingKey(listingId: number): string {
@@ -2325,6 +2392,11 @@ function App() {
   const [favoritesPreferredTab, setFavoritesPreferredTab] = useState<FavoriteTab>('buy');
   const [unreadFavoriteIds, setUnreadFavoriteIds] = useState<Set<string>>(new Set());
   const hydratedFavoriteIdsRef = useRef<Set<number>>(new Set());
+  const favoriteListingIdList = useMemo(
+    () => Array.from(new Set(favoriteListingsState.map((item) => item.listingId))).sort((left, right) => left - right),
+    [favoriteListingsState],
+  );
+  const favoriteListingIdsSignature = useMemo(() => favoriteListingIdList.join(','), [favoriteListingIdList]);
   const translatedOriginalTextRef = useRef<Map<Text, string>>(new Map());
   const translatedOriginalAttrRef = useRef<Map<Element, Record<string, string>>>(new Map());
   const translationObserverRef = useRef<MutationObserver | null>(null);
@@ -2735,6 +2807,98 @@ function App() {
     };
   }, [favoriteListingsState]);
 
+  useEffect(() => {
+    if (!user || favoriteListingIdList.length === 0) {
+      return;
+    }
+
+    let cancelled = false;
+    let snapshots = readUserJsonStorage<Record<string, number>>(user, FAVORITE_PRICE_SNAPSHOTS_STORAGE_SUFFIX, {});
+
+    const syncFavoritePrices = async () => {
+      const refreshed = await Promise.all(
+        favoriteListingIdList.map(async (listingId) => {
+          try {
+            return await apiFetch<ApiListingDetail>(`/listings/${listingId}`);
+          } catch {
+            return null;
+          }
+        }),
+      );
+
+      if (cancelled) {
+        return;
+      }
+
+      const nowIso = new Date().toISOString();
+      const incomingEvents: FavoritePriceAlertEvent[] = [];
+      const nextSnapshots = { ...snapshots };
+      const refreshedFavorites = new Map<number, FavoriteListing>();
+
+      refreshed.forEach((listing) => {
+        if (!listing) {
+          return;
+        }
+
+        const listingIdKey = String(listing.id);
+        const previousPrice = nextSnapshots[listingIdKey];
+        const currentPrice = Number(listing.price);
+        if (Number.isFinite(currentPrice)) {
+          if (Number.isFinite(previousPrice) && previousPrice !== currentPrice) {
+            const location = [listing.city, listing.district].filter(Boolean).join(', ');
+            incomingEvents.push({
+              id: `${listing.id}:${previousPrice}->${currentPrice}`,
+              listingId: listing.id,
+              title: listing.title,
+              location: location || listing.city,
+              area: `${`${listing.area}`.replace('.', ',')} m²`,
+              previousPrice,
+              currentPrice,
+              changedAt: nowIso,
+            });
+          }
+          nextSnapshots[listingIdKey] = currentPrice;
+        }
+
+        refreshedFavorites.set(listing.id, toFavoriteListing(listing));
+      });
+
+      snapshots = nextSnapshots;
+      writeUserJsonStorage(user, FAVORITE_PRICE_SNAPSHOTS_STORAGE_SUFFIX, nextSnapshots);
+
+      if (incomingEvents.length > 0) {
+        const existingEvents = readUserJsonStorage<FavoritePriceAlertEvent[]>(user, FAVORITE_PRICE_ALERTS_STORAGE_SUFFIX, []);
+        const merged = mergePriceAlertEvents(incomingEvents, existingEvents);
+        writeUserJsonStorage(user, FAVORITE_PRICE_ALERTS_STORAGE_SUFFIX, merged);
+      }
+
+      if (refreshedFavorites.size > 0) {
+        setFavoriteListingsState((current) => current.map((item) => {
+          const refreshedItem = refreshedFavorites.get(item.listingId);
+          if (!refreshedItem) {
+            return item;
+          }
+          return {
+            ...item,
+            ...refreshedItem,
+            id: item.id,
+            listingId: item.listingId,
+          };
+        }));
+      }
+    };
+
+    void syncFavoritePrices();
+    const intervalId = window.setInterval(() => {
+      void syncFavoritePrices();
+    }, 45000);
+
+    return () => {
+      cancelled = true;
+      window.clearInterval(intervalId);
+    };
+  }, [user, favoriteListingIdList, favoriteListingIdsSignature]);
+
   return (
     <div className={`site-shell ${view === 'login' ? 'login-shell' : ''}`}>
       <Header activeView={view} onNavigate={navigate} onLogout={handleLogout} hasUnreadFavorites={unreadFavoriteIds.size > 0} />
@@ -2742,6 +2906,7 @@ function App() {
         {view === 'login' && <LoginPage onLogin={handleAuthenticated} />}
         {view === 'admin' && <AdminPage onNavigate={navigate} />}
         {view === 'account' && <AccountDashboardPage onNavigate={navigate} activeView={view} />}
+        {view === 'accountPriceAlerts' && <AccountPriceAlertsPage onNavigate={navigate} activeView={view} user={user} onOpenListing={openListing} />}
         {view === 'comparison' && <AccountComparisonPage onNavigate={navigate} activeView={view} onOpenListing={openListing} />}
         {view === 'accountMeetings' && <AccountMeetingsPage onNavigate={navigate} activeView={view} />}
         {view === 'accountListings' && <AccountListingsPage onNavigate={navigate} activeView={view} onOpenListing={openListing} />}
@@ -2789,7 +2954,7 @@ function App() {
         )}
         {view === 'sell' && <SellPage onNavigate={navigate} />}
         {view === 'valuation' && <ValuationPage onNavigate={navigate} />}
-        {view === 'priceHistory' && <PriceHistoryPage onNavigate={navigate} />}
+        {view === 'priceHistory' && <PriceHistoryPage onNavigate={navigate} user={user} />}
         {view === 'districtRanking' && <DistrictRankingPage onNavigate={navigate} />}
         {view === 'negotiation' && (
           <NegotiationPage
@@ -4248,6 +4413,7 @@ function AccountSidebar({ onNavigate, activeView }: { onNavigate: (view: View) =
   const isSettingsView = activeView === 'accountSettings' || activeView === 'accountProfileEdit' || activeView === 'accountPublicProfile';
   const isSecurityView = activeView === 'accountSecurity';
   const isDashboardView = activeView === 'account';
+  const isPriceAlertsView = activeView === 'accountPriceAlerts';
   const isMeetingsView = activeView === 'accountMeetings';
   const isListingsView = activeView === 'accountListings';
   const isPriceHistoryView = activeView === 'priceHistory';
@@ -4293,7 +4459,7 @@ function AccountSidebar({ onNavigate, activeView }: { onNavigate: (view: View) =
         <button><Icon name="search" /> Zapisane wyszukiwania <span>5</span></button>
         <button><Icon name="heart" /> Ulubione ogłoszenia <span>12</span></button>
         <button><Icon name="clock" /> Ostatnio oglądane</button>
-        <button><Icon name="bell" /> Alerty cenowe <span>3</span></button>
+        <button className={isPriceAlertsView ? 'active' : ''} onClick={() => onNavigate('accountPriceAlerts')}><Icon name="bell" /> Alerty cenowe <span>3</span></button>
         <button className={isComparisonView ? 'active' : ''} onClick={() => onNavigate('comparison')}><Icon name="shuffle" /> Porównanie mieszkań</button>
       </div>
 
@@ -4776,6 +4942,228 @@ function AccountDashboardPage({ onNavigate, activeView }: { onNavigate: (view: V
   );
 }
 
+function AccountPriceAlertsPage({
+  onNavigate,
+  activeView,
+  user,
+  onOpenListing,
+}: {
+  onNavigate: (view: View) => void;
+  activeView: View;
+  user: AuthUser | null;
+  onOpenListing: (id: number) => void;
+}) {
+  const [cityAlerts, setCityAlerts] = useState<CityPriceAlertSubscription[]>([]);
+  const [priceEvents, setPriceEvents] = useState<FavoritePriceAlertEvent[]>([]);
+
+  useEffect(() => {
+    if (!user) {
+      setCityAlerts([]);
+      setPriceEvents([]);
+      return;
+    }
+
+    const hydrate = () => {
+      setCityAlerts(readUserJsonStorage<CityPriceAlertSubscription[]>(user, CITY_PRICE_ALERTS_STORAGE_SUFFIX, []));
+      setPriceEvents(readUserJsonStorage<FavoritePriceAlertEvent[]>(user, FAVORITE_PRICE_ALERTS_STORAGE_SUFFIX, []));
+    };
+
+    hydrate();
+    const intervalId = window.setInterval(hydrate, 10000);
+    return () => window.clearInterval(intervalId);
+  }, [user]);
+
+  const latestEvent = priceEvents[0] ?? null;
+  const cityInsights = useMemo(() => cityAlerts.map((subscription, index) => {
+    const market = HISTORY_PRICE_MARKETS.find((item) => item.key === subscription.key) ?? findHistoryMarket(subscription.label);
+    const district = historyShortMarketLabel(market ?? resolveHistoryMarket(subscription.label));
+    const rawPrice = market?.apartmentM2 ?? estimateHistoryLocationPrice(subscription.label).price;
+    const price = Math.round(rawPrice * HISTORY_PROPERTY_MULTIPLIERS[subscription.propertyType] * HISTORY_MARKET_MULTIPLIERS[subscription.marketType]);
+    const delta = (market?.trend24 ?? (0.03 + ((index % 4) * 0.008))) * 100;
+    return {
+      key: subscription.key,
+      district,
+      price,
+      delta,
+      barWidth: Math.max(28, 78 - (index * 9)),
+    };
+  }), [cityAlerts]);
+
+  const cityAveragePrice = cityInsights.length > 0
+    ? Math.round(cityInsights.reduce((sum, item) => sum + item.price, 0) / cityInsights.length)
+    : 0;
+  const cityAverageDelta = cityInsights.length > 0
+    ? cityInsights.reduce((sum, item) => sum + item.delta, 0) / cityInsights.length
+    : 0;
+
+  const activeAlerts = cityAlerts.map((subscription) => ({
+    title: subscription.label,
+    meta: `${subscription.propertyType} • ${subscription.marketType}`,
+    key: subscription.key,
+  }));
+
+  const removeAlert = (key: string) => {
+    if (!user) {
+      return;
+    }
+    setCityAlerts((current) => {
+      const next = current.filter((item) => item.key !== key);
+      writeUserJsonStorage(user, CITY_PRICE_ALERTS_STORAGE_SUFFIX, next);
+      return next;
+    });
+  };
+
+  const hasPriceDrop = latestEvent ? latestEvent.currentPrice < latestEvent.previousPrice : false;
+  const latestDelta = latestEvent ? latestEvent.currentPrice - latestEvent.previousPrice : 0;
+  const latestDeltaPercent = latestEvent && latestEvent.previousPrice > 0
+    ? (Math.abs(latestDelta) / latestEvent.previousPrice) * 100
+    : 0;
+
+  return (
+    <section className="account-settings-page price-alerts-page" aria-label="Powiadomienia i alerty cenowe">
+      <div className="account-layout">
+        <AccountSidebar onNavigate={onNavigate} activeView={activeView} />
+
+        <div className="account-main account-settings-main">
+          <div className="price-alerts-heading">
+            <small>Strona główna <Icon name="arrow" /> Powiadomienia i alerty</small>
+            <div>
+              <h1>Powiadomienia i alerty</h1>
+              <p>Śledź zmiany cen w wybranych lokalizacjach i otrzymuj powiadomienia, które pomogą Ci podjąć lepszą decyzję.</p>
+            </div>
+            <button type="button" className="price-alerts-settings">
+              <Icon name="gear" /> Ustawienia alertów
+            </button>
+          </div>
+
+          <section className="price-alerts-hero">
+            <div className="price-alerts-hero-main">
+              <span className="price-alerts-badge">Alert cenowy</span>
+              <h2>
+                {latestEvent
+                  ? (hasPriceDrop ? 'Cena mieszkania spadła!' : 'Cena mieszkania zmieniła się')
+                  : 'Brak nowych zmian cen'}
+              </h2>
+              <p>{latestEvent ? latestEvent.title : 'Dodaj oferty do ulubionych, aby śledzić zmiany cen.'}</p>
+              <small><Icon name="pin" /> {latestEvent ? latestEvent.location : 'Wybierz mieszkania, które Cię interesują'}</small>
+              <div className="price-alerts-pricing">
+                <strong>{latestEvent ? formatPln(latestEvent.currentPrice) : '0 zł'}</strong>
+                <em>{latestEvent ? formatPln(latestEvent.previousPrice) : '0 zł'}</em>
+                <span>
+                  {latestEvent
+                    ? `${latestDelta <= 0 ? '-' : '+'} ${formatPln(Math.abs(latestDelta))} (${latestDeltaPercent.toFixed(1).replace('.', ',')}%)`
+                    : 'Brak porównań'}
+                </span>
+              </div>
+              <div className="price-alerts-meta">
+                <span>Powierzchnia: <b>{latestEvent ? latestEvent.area : '—'}</b></span>
+                <span>
+                  Cena za m²: <b>
+                    {latestEvent
+                      ? formatM2(Math.round(latestEvent.currentPrice / Math.max(1, Number(latestEvent.area.replace(/[^\d,]/g, '').replace(',', '.')) || 1)))
+                      : '—'}
+                  </b>
+                </span>
+              </div>
+            </div>
+
+            <div className="price-alerts-hero-image" style={{ backgroundImage: `url(${heroImage})` }} />
+
+            <aside className="price-alerts-hero-side">
+              <strong>Alert utworzony dla Ciebie</strong>
+              <ul>
+                <li>Ulubione oferty: <b>{priceEvents.length}</b></li>
+                <li>Aktywne alerty lokalizacji: <b>{cityAlerts.length}</b></li>
+                <li>Ostatnia aktualizacja: <b>{latestEvent ? new Date(latestEvent.changedAt).toLocaleString('pl-PL') : 'Brak'}</b></li>
+                <li>Status: <b>{latestEvent ? 'Aktywny monitoring cen' : 'Czeka na pierwszą zmianę ceny'}</b></li>
+              </ul>
+              <button type="button" onClick={() => { if (latestEvent) { onOpenListing(latestEvent.listingId); } }} disabled={!latestEvent}>
+                Zobacz ofertę <Icon name="arrow" />
+              </button>
+            </aside>
+          </section>
+
+          <section className="price-alerts-grid">
+            <article className="price-alerts-card">
+              <header>
+                <h3>Średnia zmiana ceny za m² w alertach</h3>
+                <p>{cityInsights.length > 0 ? `Na podstawie ${cityInsights.length} aktywnych lokalizacji` : 'Dodaj lokalizację, aby aktywować wykres'}</p>
+              </header>
+              <div className="price-alerts-kpi">
+                <strong>{cityInsights.length > 0 ? formatM2(cityAveragePrice) : '0 zł/m²'}</strong>
+                <span>{cityInsights.length > 0 ? `${cityAverageDelta >= 0 ? '+' : ''}${cityAverageDelta.toFixed(1).replace('.', ',')}%` : '0,0%'}</span>
+              </div>
+              <svg viewBox="0 0 320 130" aria-hidden="true" className="price-alerts-chart">
+                <defs>
+                  <linearGradient id="priceChartFill" x1="0" x2="0" y1="0" y2="1">
+                    <stop offset="0%" stopColor="#26b36a" stopOpacity="0.34" />
+                    <stop offset="100%" stopColor="#26b36a" stopOpacity="0" />
+                  </linearGradient>
+                </defs>
+                <path d="M20 102 L58 92 L89 94 L116 85 L146 80 L175 81 L203 74 L234 67 L266 69 L300 44"
+                  className="price-alerts-chart-line" />
+                <path d="M20 102 L58 92 L89 94 L116 85 L146 80 L175 81 L203 74 L234 67 L266 69 L300 44 L300 120 L20 120 Z"
+                  fill="url(#priceChartFill)" />
+              </svg>
+            </article>
+
+            <article className="price-alerts-card">
+              <header>
+                <h3>Zmiana ceny za m² w dzielnicach</h3>
+                <p>Ostatnie 12 miesięcy</p>
+              </header>
+              <div className="price-alerts-districts">
+                {cityInsights.length > 0 ? cityInsights.slice(0, 5).map((item) => (
+                  <div key={item.key}>
+                    <strong>{item.district}</strong>
+                    <span className="price-alerts-district-bar"><i style={{ width: `${item.barWidth}%` }} /></span>
+                    <em>{formatM2(item.price)}</em>
+                    <b>{item.delta >= 0 ? '+' : ''}{item.delta.toFixed(1).replace('.', ',')}%</b>
+                  </div>
+                )) : (
+                  <div>
+                    <strong>Brak danych</strong>
+                    <span className="price-alerts-district-bar"><i style={{ width: '28%' }} /></span>
+                    <em>0 zł/m²</em>
+                    <b>0,0%</b>
+                  </div>
+                )}
+              </div>
+              <button type="button" className="price-alerts-link" onClick={() => onNavigate('priceHistory')}>Dodaj kolejne lokalizacje</button>
+            </article>
+
+            <article className="price-alerts-card price-alerts-active-list">
+              <header>
+                <h3>Twoje alerty</h3>
+              </header>
+              <div className="price-alerts-active-items">
+                {activeAlerts.length > 0 ? activeAlerts.map((item) => (
+                  <button key={item.key} type="button" onClick={() => removeAlert(item.key)}>
+                    <div>
+                      <strong>{item.title}</strong>
+                      <small>{item.meta}</small>
+                    </div>
+                    <span>Usuń</span>
+                  </button>
+                )) : (
+                  <button type="button" onClick={() => onNavigate('priceHistory')}>
+                    <div>
+                      <strong>Brak aktywnych alertów</strong>
+                      <small>Przejdź do historii cen i dodaj pierwszą lokalizację.</small>
+                    </div>
+                    <span>Dodaj</span>
+                  </button>
+                )}
+              </div>
+              <button type="button" className="price-alerts-manage" onClick={() => onNavigate('priceHistory')}>Zarządzaj alertami</button>
+            </article>
+          </section>
+        </div>
+      </div>
+    </section>
+  );
+}
+
 function AccountComparisonPage({ onNavigate, activeView, onOpenListing }: { onNavigate: (view: View) => void; activeView: View; onOpenListing: (id: number) => void }) {
   type ComparisonPropertyFilter = 'ALL' | ApiPropertyType | 'LAND' | 'COMMERCIAL' | 'ROOM';
 
@@ -13039,12 +13427,14 @@ function historyShortMarketLabel(market: PriceHistoryMarket) {
   return tail;
 }
 
-function PriceHistoryPage({ onNavigate }: { onNavigate: (view: View) => void }) {
+function PriceHistoryPage({ onNavigate, user }: { onNavigate: (view: View) => void; user: AuthUser | null }) {
   const [locationInput, setLocationInput] = useState('');
   const [selectedMarket, setSelectedMarket] = useState<PriceHistoryMarket | null>(null);
   const [propertyType, setPropertyType] = useState<HistoryPropertyType>('Mieszkanie');
   const [marketType, setMarketType] = useState<HistoryMarketType>('Wtórny i pierwotny');
   const [period, setPeriod] = useState<HistoryPeriod>('2026');
+  const [createAlertFeedback, setCreateAlertFeedback] = useState<string | null>(null);
+  const [cityAlertSubscriptions, setCityAlertSubscriptions] = useState<CityPriceAlertSubscription[]>([]);
   const [suggestions, setSuggestions] = useState<PlaceSuggestion[]>([]);
   const [suggestOpen, setSuggestOpen] = useState(false);
   const [suggestLoading, setSuggestLoading] = useState(false);
@@ -13119,6 +13509,9 @@ function PriceHistoryPage({ onNavigate }: { onNavigate: (view: View) => void })
   const tooltipHeight = 54;
   const tooltipX = hoveredPoint ? Math.min(chartWidth - tooltipWidth - 8, Math.max(8, hoveredPoint.x - tooltipWidth / 2)) : 0;
   const tooltipY = hoveredPoint ? Math.max(8, hoveredPoint.y - tooltipHeight - 14) : 0;
+  const selectedMarketAlreadyAlerted = selectedMarket
+    ? cityAlertSubscriptions.some((item) => item.key === selectedMarket.key)
+    : false;
 
   const handleHistoryChartMouseMove = (event: ReactMouseEvent<HTMLDivElement>) => {
     if (!hasSelectedMarket) {
@@ -13131,6 +13524,14 @@ function PriceHistoryPage({ onNavigate }: { onNavigate: (view: View) => void })
     setHoveredHistoryIndex(nextIndex);
   };
 
+  useEffect(() => {
+    if (!user) {
+      setCityAlertSubscriptions([]);
+      return;
+    }
+    setCityAlertSubscriptions(readUserJsonStorage<CityPriceAlertSubscription[]>(user, CITY_PRICE_ALERTS_STORAGE_SUFFIX, []));
+  }, [user]);
+
   useEffect(() => {
     if (skipNextFetch.current) {
       skipNextFetch.current = false;
@@ -13203,6 +13604,43 @@ function PriceHistoryPage({ onNavigate }: { onNavigate: (view: View) => void })
     setPeriod('2026');
   };
 
+  const createCityAlert = () => {
+    if (!user) {
+      setCreateAlertFeedback('Zaloguj się, aby dodać alert cenowy.');
+      onNavigate('login');
+      return;
+    }
+    if (!selectedMarket) {
+      setCreateAlertFeedback('Najpierw wybierz lokalizację do monitorowania.');
+      return;
+    }
+
+    const subscription: CityPriceAlertSubscription = {
+      key: selectedMarket.key,
+      label: selectedMarket.label,
+      city: selectedMarket.city,
+      region: selectedMarket.region,
+      propertyType,
+      marketType,
+      createdAt: new Date().toISOString(),
+    };
+
+    setCityAlertSubscriptions((current) => {
+      if (current.some((item) => item.key === subscription.key)) {
+        setCreateAlertFeedback('Ten alert już jest aktywny.');
+        return current;
+      }
+      const next = [subscription, ...current];
+      writeUserJsonStorage(user, CITY_PRICE_ALERTS_STORAGE_SUFFIX, next);
+      setCreateAlertFeedback('Alert został dodany do Twojego panelu.');
+      return next;
+    });
+
+    window.setTimeout(() => {
+      onNavigate('accountPriceAlerts');
+    }, 280);
+  };
+
   return (
     <section className="history-page" aria-label="Historia cen">
       <div className="history-shell">
@@ -13351,7 +13789,8 @@ function PriceHistoryPage({ onNavigate }: { onNavigate: (view: View) => void })
             <section className="history-alert-card">
               <span><Icon name="bell" /></span>
               <p><strong>Chcesz być na bieżąco?</strong><small>Ustaw alert cenowy i otrzymuj powiadomienia o zmianach cen w wybranej lokalizacji.</small></p>
-              <button type="button"><Icon name="bell" /> Utwórz alert cenowy</button>
+              <button type="button" onClick={createCityAlert}><Icon name="bell" /> {selectedMarketAlreadyAlerted ? 'Alert już aktywny' : 'Utwórz alert cenowy'}</button>
+              {createAlertFeedback && <small>{createAlertFeedback}</small>}
             </section>
           </div>
 

frontend/src/styles.css

@@ -17099,6 +17099,403 @@ svg {
   align-content: start;
 }
 
+.price-alerts-page {
+  background: linear-gradient(180deg, #f4f7fb 0%, #eef3f9 100%);
+}
+
+.price-alerts-heading {
+  display: grid;
+  gap: 10px;
+}
+
+.price-alerts-heading small {
+  align-items: center;
+  color: #7a8ba0;
+  display: inline-flex;
+  font-size: 11px;
+  font-weight: 850;
+  gap: 6px;
+}
+
+.price-alerts-heading small svg {
+  color: #a2afc1;
+  font-size: 12px;
+  transform: rotate(-45deg);
+}
+
+.price-alerts-heading h1 {
+  color: #162742;
+  font-size: 38px;
+  letter-spacing: -0.01em;
+  margin: 0;
+}
+
+.price-alerts-heading p {
+  color: #5d7088;
+  font-size: 13px;
+  font-weight: 760;
+  margin: 8px 0 0;
+  max-width: 780px;
+}
+
+.price-alerts-settings {
+  align-items: center;
+  background: #ffffff;
+  border: 1px solid #dbe5f0;
+  border-radius: 9px;
+  color: #2a3e58;
+  display: inline-flex;
+  font-size: 12px;
+  font-weight: 900;
+  gap: 7px;
+  height: 38px;
+  justify-self: end;
+  padding: 0 13px;
+}
+
+.price-alerts-hero {
+  background: #ffffff;
+  border: 1px solid #dfe8f1;
+  border-radius: 14px;
+  display: grid;
+  gap: 14px;
+  grid-template-columns: minmax(280px, 1fr) minmax(220px, 360px) minmax(200px, 280px);
+  padding: 16px;
+}
+
+.price-alerts-hero-main h2 {
+  color: #152841;
+  font-size: 33px;
+  line-height: 1.05;
+  margin: 8px 0 2px;
+}
+
+.price-alerts-hero-main p {
+  color: #2b4059;
+  font-size: 17px;
+  font-weight: 800;
+  margin: 0;
+}
+
+.price-alerts-hero-main > small {
+  align-items: center;
+  color: #5f738c;
+  display: inline-flex;
+  font-size: 12px;
+  font-weight: 700;
+  gap: 5px;
+  margin-top: 9px;
+}
+
+.price-alerts-badge {
+  background: #e9f8ef;
+  border-radius: 999px;
+  color: #0f9657;
+  display: inline-block;
+  font-size: 10px;
+  font-weight: 900;
+  letter-spacing: 0.04em;
+  padding: 3px 9px;
+  text-transform: uppercase;
+}
+
+.price-alerts-pricing {
+  align-items: baseline;
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px 11px;
+  margin-top: 14px;
+}
+
+.price-alerts-pricing strong {
+  color: #129256;
+  font-size: 39px;
+  line-height: 1;
+}
+
+.price-alerts-pricing em {
+  color: #8191a5;
+  font-size: 19px;
+  font-style: normal;
+  font-weight: 700;
+  text-decoration: line-through;
+}
+
+.price-alerts-pricing span {
+  color: #f04444;
+  font-size: 15px;
+  font-weight: 900;
+}
+
+.price-alerts-meta {
+  color: #71839b;
+  display: flex;
+  flex-wrap: wrap;
+  font-size: 12px;
+  font-weight: 750;
+  gap: 8px 18px;
+  margin-top: 8px;
+}
+
+.price-alerts-meta b {
+  color: #2a405a;
+}
+
+.price-alerts-hero-image {
+  background-position: center;
+  background-repeat: no-repeat;
+  background-size: cover;
+  border-radius: 12px;
+  min-height: 210px;
+}
+
+.price-alerts-hero-side {
+  background: #f4fbf7;
+  border: 1px solid #dfeee6;
+  border-radius: 12px;
+  display: grid;
+  gap: 10px;
+  padding: 14px;
+}
+
+.price-alerts-hero-side strong {
+  color: #148c53;
+  font-size: 14px;
+}
+
+.price-alerts-hero-side ul {
+  color: #3d556d;
+  display: grid;
+  font-size: 12px;
+  font-weight: 760;
+  gap: 6px;
+  list-style: none;
+  margin: 0;
+  padding: 0;
+}
+
+.price-alerts-hero-side b {
+  color: #1f354f;
+}
+
+.price-alerts-hero-side button {
+  align-items: center;
+  background: #17a762;
+  border: 0;
+  border-radius: 8px;
+  color: #ffffff;
+  display: inline-flex;
+  font-size: 12px;
+  font-weight: 900;
+  gap: 7px;
+  height: 35px;
+  justify-content: center;
+}
+
+.price-alerts-grid {
+  display: grid;
+  gap: 12px;
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+}
+
+.price-alerts-card {
+  background: #ffffff;
+  border: 1px solid #dfe8f1;
+  border-radius: 12px;
+  display: grid;
+  gap: 10px;
+  padding: 14px;
+}
+
+.price-alerts-card header h3 {
+  color: #182a45;
+  font-size: 18px;
+  margin: 0;
+}
+
+.price-alerts-card header p {
+  color: #6b7d93;
+  font-size: 11px;
+  font-weight: 800;
+  margin: 5px 0 0;
+}
+
+.price-alerts-kpi {
+  align-items: baseline;
+  display: flex;
+  gap: 12px;
+}
+
+.price-alerts-kpi strong {
+  color: #162a44;
+  font-size: 30px;
+  line-height: 1;
+}
+
+.price-alerts-kpi span {
+  color: #14a35f;
+  font-size: 18px;
+  font-weight: 900;
+}
+
+.price-alerts-chart {
+  height: 132px;
+  width: 100%;
+}
+
+.price-alerts-chart-line {
+  fill: none;
+  stroke: #26b36a;
+  stroke-linecap: round;
+  stroke-linejoin: round;
+  stroke-width: 3;
+}
+
+.price-alerts-districts {
+  display: grid;
+  gap: 9px;
+}
+
+.price-alerts-districts div {
+  align-items: center;
+  display: grid;
+  gap: 8px;
+  grid-template-columns: 88px minmax(90px, 1fr) auto auto;
+}
+
+.price-alerts-districts strong {
+  color: #233852;
+  font-size: 12px;
+}
+
+.price-alerts-district-bar {
+  background: #edf1f6;
+  border-radius: 999px;
+  display: block;
+  height: 8px;
+  overflow: hidden;
+}
+
+.price-alerts-district-bar i {
+  background: linear-gradient(90deg, #25b269 0%, #5ac987 100%);
+  border-radius: 999px;
+  display: block;
+  height: 100%;
+}
+
+.price-alerts-districts em {
+  color: #2d435e;
+  font-size: 12px;
+  font-style: normal;
+  font-weight: 820;
+}
+
+.price-alerts-districts b {
+  color: #15a35f;
+  font-size: 12px;
+}
+
+.price-alerts-link {
+  background: transparent;
+  border: 0;
+  color: #18a661;
+  font-size: 12px;
+  font-weight: 900;
+  justify-self: start;
+  padding: 0;
+}
+
+.price-alerts-active-list {
+  align-content: start;
+}
+
+.price-alerts-active-items {
+  display: grid;
+  gap: 8px;
+}
+
+.price-alerts-active-items button {
+  align-items: center;
+  background: #fbfcfe;
+  border: 1px solid #e2eaf3;
+  border-radius: 9px;
+  color: #21364f;
+  display: grid;
+  gap: 8px;
+  grid-template-columns: minmax(0, 1fr) auto;
+  padding: 9px;
+  text-align: left;
+}
+
+.price-alerts-active-items strong {
+  color: #1d3049;
+  display: block;
+  font-size: 12px;
+}
+
+.price-alerts-active-items small {
+  color: #6d7f96;
+  display: block;
+  font-size: 10px;
+  font-weight: 750;
+  margin-top: 2px;
+}
+
+.price-alerts-active-items span {
+  background: #e9f8ef;
+  border-radius: 999px;
+  color: #119659;
+  font-size: 10px;
+  font-weight: 900;
+  padding: 2px 8px;
+}
+
+.price-alerts-manage {
+  background: #f5f8fc;
+  border: 1px solid #dce6f1;
+  border-radius: 8px;
+  color: #334a64;
+  font-size: 12px;
+  font-weight: 900;
+  height: 35px;
+}
+
+@media (max-width: 1300px) {
+  .price-alerts-grid {
+    grid-template-columns: 1fr;
+  }
+
+  .price-alerts-hero {
+    grid-template-columns: 1fr;
+  }
+
+  .price-alerts-heading h1 {
+    font-size: 31px;
+  }
+
+  .price-alerts-settings {
+    justify-self: start;
+  }
+}
+
+@media (max-width: 740px) {
+  .price-alerts-pricing strong {
+    font-size: 30px;
+  }
+
+  .price-alerts-pricing em {
+    font-size: 15px;
+  }
+
+  .price-alerts-pricing span {
+    font-size: 12px;
+  }
+
+  .price-alerts-districts div {
+    grid-template-columns: 1fr;
+  }
+}
+
 .settings-head h1 {
   color: #1a2c46;
   font-size: 43px;