diff --git a/apps/web/app/(admin)/admin/kyc/page.tsx b/apps/web/app/(admin)/admin/kyc/page.tsx
index 43b89e7..841090b 100644
--- a/apps/web/app/(admin)/admin/kyc/page.tsx
+++ b/apps/web/app/(admin)/admin/kyc/page.tsx
@@ -1,6 +1,7 @@
 'use client';
 
 import { useEffect, useState, useCallback } from 'react';
+import Image from 'next/image';
 import {
   CheckCircle,
   XCircle,
@@ -97,11 +98,13 @@ function KycDetailView({ item, onApprove, onReject }: {
             {kycData.frontImageUrl && (
               <div className="space-y-1">
                 <div className="text-xs text-muted-foreground">Mặt trước</div>
-                <div className="aspect-video overflow-hidden rounded-md border bg-muted">
-                  <img
+                <div className="relative aspect-video overflow-hidden rounded-md border bg-muted">
+                  <Image
                     src={kycData.frontImageUrl}
                     alt="Mặt trước giấy tờ"
-                    className="h-full w-full object-contain"
+                    fill
+                    sizes="(max-width: 768px) 100vw, 400px"
+                    className="object-contain"
                   />
                 </div>
               </div>
@@ -109,11 +112,13 @@ function KycDetailView({ item, onApprove, onReject }: {
             {kycData.backImageUrl && (
               <div className="space-y-1">
                 <div className="text-xs text-muted-foreground">Mặt sau</div>
-                <div className="aspect-video overflow-hidden rounded-md border bg-muted">
-                  <img
+                <div className="relative aspect-video overflow-hidden rounded-md border bg-muted">
+                  <Image
                     src={kycData.backImageUrl}
                     alt="Mặt sau giấy tờ"
-                    className="h-full w-full object-contain"
+                    fill
+                    sizes="(max-width: 768px) 100vw, 400px"
+                    className="object-contain"
                   />
                 </div>
               </div>
@@ -121,11 +126,13 @@ function KycDetailView({ item, onApprove, onReject }: {
             {kycData.selfieUrl && (
               <div className="space-y-1">
                 <div className="text-xs text-muted-foreground">Ảnh selfie</div>
-                <div className="aspect-video overflow-hidden rounded-md border bg-muted">
-                  <img
+                <div className="relative aspect-video overflow-hidden rounded-md border bg-muted">
+                  <Image
                     src={kycData.selfieUrl}
                     alt="Selfie"
-                    className="h-full w-full object-contain"
+                    fill
+                    sizes="(max-width: 768px) 100vw, 400px"
+                    className="object-contain"
                   />
                 </div>
               </div>
diff --git a/apps/web/app/(auth)/login/page.tsx b/apps/web/app/(auth)/login/page.tsx
index b36c01e..79c28a1 100644
--- a/apps/web/app/(auth)/login/page.tsx
+++ b/apps/web/app/(auth)/login/page.tsx
@@ -22,12 +22,16 @@ export default function LoginPage() {
   const [showPassword, setShowPassword] = useState(false);
 
   const oauthError = searchParams.get('error');
-  const oauthErrorMessage =
-    oauthError === 'oauth_failed'
-      ? 'Đăng nhập bằng mạng xã hội thất bại. Vui lòng thử lại.'
-      : oauthError
-        ? decodeURIComponent(oauthError)
-        : null;
+  const OAUTH_ERROR_MESSAGES: Record<string, string> = {
+    oauth_failed: 'Đăng nhập bằng mạng xã hội thất bại. Vui lòng thử lại.',
+    access_denied: 'Bạn đã từ chối quyền truy cập. Vui lòng thử lại.',
+    invalid_request: 'Yêu cầu đăng nhập không hợp lệ. Vui lòng thử lại.',
+    server_error: 'Lỗi máy chủ. Vui lòng thử lại sau.',
+    temporarily_unavailable: 'Dịch vụ tạm thời không khả dụng. Vui lòng thử lại sau.',
+  };
+  const oauthErrorMessage = oauthError
+    ? OAUTH_ERROR_MESSAGES[oauthError] ?? 'Đã xảy ra lỗi khi đăng nhập. Vui lòng thử lại.'
+    : null;
 
   const {
     register,
diff --git a/apps/web/app/(dashboard)/dashboard/page.tsx b/apps/web/app/(dashboard)/dashboard/page.tsx
index c9f665e..2e452fc 100644
--- a/apps/web/app/(dashboard)/dashboard/page.tsx
+++ b/apps/web/app/(dashboard)/dashboard/page.tsx
@@ -1,6 +1,7 @@
 'use client';
 
 import { useEffect, useState } from 'react';
+import Image from 'next/image';
 import Link from 'next/link';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
@@ -282,12 +283,14 @@ export default function DashboardPage() {
                   href={`/listings/${listing.id}`}
                   className="flex items-center gap-4 rounded-lg border p-3 transition-colors hover:bg-accent"
                 >
-                  <div className="h-12 w-16 flex-shrink-0 overflow-hidden rounded bg-muted">
+                  <div className="relative h-12 w-16 flex-shrink-0 overflow-hidden rounded bg-muted">
                     {listing.property.media.length > 0 ? (
-                      <img
-                        src={listing.property.media[0]?.url}
-                        alt=""
-                        className="h-full w-full object-cover"
+                      <Image
+                        src={listing.property.media[0]?.url ?? ''}
+                        alt={listing.property.title}
+                        fill
+                        sizes="64px"
+                        className="object-cover"
                       />
                     ) : (
                       <div className="flex h-full items-center justify-center text-xs text-muted-foreground">
diff --git a/apps/web/app/(dashboard)/listings/page.tsx b/apps/web/app/(dashboard)/listings/page.tsx
index f11d697..0c2e0da 100644
--- a/apps/web/app/(dashboard)/listings/page.tsx
+++ b/apps/web/app/(dashboard)/listings/page.tsx
@@ -1,6 +1,7 @@
 'use client';
 
 import * as React from 'react';
+import Image from 'next/image';
 import Link from 'next/link';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
@@ -203,14 +204,16 @@ export default function ListingsPage() {
               <Card className="h-full overflow-hidden transition-shadow hover:shadow-md">
                 <div className="relative aspect-[4/3] bg-muted">
                   {listing.property.media.length > 0 ? (
-                    <img
-                      src={listing.property.media[0]?.url}
+                    <Image
+                      src={listing.property.media[0]?.url ?? ''}
                       alt={listing.property.title}
-                      className="h-full w-full object-cover"
+                      fill
+                      sizes="(max-width: 640px) 100vw, (max-width: 1024px) 50vw, 33vw"
+                      className="object-cover"
                     />
                   ) : (
                     <div className="flex h-full items-center justify-center text-muted-foreground">
-                      Chua co anh
+                      Chưa có ảnh
                     </div>
                   )}
                   <div className="absolute left-2 top-2">
@@ -279,12 +282,14 @@ export default function ListingsPage() {
                           href={`/listings/${listing.id}`}
                           className="group flex items-center gap-3"
                         >
-                          <div className="h-10 w-14 flex-shrink-0 overflow-hidden rounded bg-muted">
+                          <div className="relative h-10 w-14 flex-shrink-0 overflow-hidden rounded bg-muted">
                             {listing.property.media.length > 0 ? (
-                              <img
-                                src={listing.property.media[0]?.url}
-                                alt=""
-                                className="h-full w-full object-cover"
+                              <Image
+                                src={listing.property.media[0]?.url ?? ''}
+                                alt={listing.property.title}
+                                fill
+                                sizes="56px"
+                                className="object-cover"
                               />
                             ) : (
                               <div className="flex h-full items-center justify-center text-xs text-muted-foreground">
diff --git a/apps/web/app/(public)/page.tsx b/apps/web/app/(public)/page.tsx
index 2548b4c..411fbd8 100644
--- a/apps/web/app/(public)/page.tsx
+++ b/apps/web/app/(public)/page.tsx
@@ -37,15 +37,22 @@ export default function LandingPage() {
   const [propertyType, setPropertyType] = React.useState('');
   const [featuredListings, setFeaturedListings] = React.useState<ListingDetail[]>([]);
   const [loadingFeatured, setLoadingFeatured] = React.useState(true);
+  const [featuredError, setFeaturedError] = React.useState(false);
 
-  React.useEffect(() => {
+  const fetchFeatured = React.useCallback(() => {
+    setLoadingFeatured(true);
+    setFeaturedError(false);
     listingsApi
       .search({ status: 'ACTIVE', limit: 6 })
       .then((res) => setFeaturedListings(res.data))
-      .catch(() => {})
+      .catch(() => setFeaturedError(true))
       .finally(() => setLoadingFeatured(false));
   }, []);
 
+  React.useEffect(() => {
+    fetchFeatured();
+  }, [fetchFeatured]);
+
   const handleSearch = (e: React.FormEvent) => {
     e.preventDefault();
     const params = new URLSearchParams();
@@ -147,6 +154,13 @@ export default function LandingPage() {
             <div className="mt-8 flex min-h-[300px] items-center justify-center">
               <div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
             </div>
+          ) : featuredError ? (
+            <div className="mt-8 flex min-h-[200px] flex-col items-center justify-center gap-3 text-muted-foreground">
+              <p>Không thể tải tin đăng. Vui lòng thử lại.</p>
+              <Button variant="outline" size="sm" onClick={fetchFeatured}>
+                Thử lại
+              </Button>
+            </div>
           ) : featuredListings.length > 0 ? (
             <div className="mt-8 grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
               {featuredListings.map((listing) => (
diff --git a/apps/web/app/(public)/search/page.tsx b/apps/web/app/(public)/search/page.tsx
index 75c3108..85c1783 100644
--- a/apps/web/app/(public)/search/page.tsx
+++ b/apps/web/app/(public)/search/page.tsx
@@ -42,6 +42,7 @@ function SearchContent() {
   const [page, setPage] = React.useState(Number(searchParams.get('page')) || 1);
   const [result, setResult] = React.useState<PaginatedResult<ListingDetail> | null>(null);
   const [loading, setLoading] = React.useState(true);
+  const [searchError, setSearchError] = React.useState(false);
   const [viewMode, setViewMode] = React.useState<ViewMode>('list');
   const [showMobileFilters, setShowMobileFilters] = React.useState(false);
   const [selectedListingId, setSelectedListingId] = React.useState<string | undefined>();
@@ -67,10 +68,14 @@ function SearchContent() {
     if (filters.maxArea) params['maxArea'] = Number(filters.maxArea);
     if (filters.bedrooms) params['bedrooms'] = Number(filters.bedrooms);
 
+    setSearchError(false);
     listingsApi
       .search(params)
       .then(setResult)
-      .catch(() => setResult(null))
+      .catch(() => {
+        setResult(null);
+        setSearchError(true);
+      })
       .finally(() => setLoading(false));
   }, [filters, page]);
 
@@ -214,6 +219,8 @@ function SearchContent() {
             <SearchResults
               result={result}
               loading={loading}
+              error={searchError}
+              onRetry={fetchListings}
               page={page}
               sort={filters.sort}
               onPageChange={setPage}
@@ -236,6 +243,8 @@ function SearchContent() {
                 <SearchResults
                   result={result}
                   loading={loading}
+                  error={searchError}
+                  onRetry={fetchListings}
                   page={page}
                   sort={filters.sort}
                   onPageChange={setPage}
diff --git a/apps/web/app/error.tsx b/apps/web/app/error.tsx
index 82c322d..62be3e5 100644
--- a/apps/web/app/error.tsx
+++ b/apps/web/app/error.tsx
@@ -10,7 +10,13 @@ export default function GlobalError({
   reset: () => void;
 }) {
   useEffect(() => {
-    console.error('Unhandled error:', error);
+    // Report to error tracking service in production; log digest only
+    if (process.env.NODE_ENV === 'production') {
+      // TODO: integrate with Sentry/Datadog when available
+      // errorReporter.captureException(error);
+    } else {
+      console.error('Unhandled error:', error);
+    }
   }, [error]);
 
   return (
diff --git a/apps/web/components/listings/image-gallery.tsx b/apps/web/components/listings/image-gallery.tsx
index 900c114..f0339ea 100644
--- a/apps/web/components/listings/image-gallery.tsx
+++ b/apps/web/components/listings/image-gallery.tsx
@@ -1,6 +1,7 @@
 'use client';
 
 import * as React from 'react';
+import Image from 'next/image';
 import { cn } from '@/lib/utils';
 import type { PropertyMedia } from '@/lib/listings-api';
 
@@ -30,10 +31,13 @@ export function ImageGallery({ media, className }: ImageGalleryProps) {
     <div className={cn('space-y-3', className)}>
       {/* Main image */}
       <div className="relative aspect-video overflow-hidden rounded-lg bg-muted">
-        <img
-          src={images[selectedIndex]?.url}
+        <Image
+          src={images[selectedIndex]?.url ?? ''}
           alt={images[selectedIndex]?.caption || `Ảnh ${selectedIndex + 1}`}
-          className="h-full w-full object-cover"
+          fill
+          sizes="(max-width: 768px) 100vw, 60vw"
+          className="object-cover"
+          priority={selectedIndex === 0}
         />
         {images.length > 1 && (
           <>
@@ -66,14 +70,16 @@ export function ImageGallery({ media, className }: ImageGalleryProps) {
               key={img.id}
               onClick={() => setSelectedIndex(index)}
               className={cn(
-                'h-16 w-16 flex-shrink-0 overflow-hidden rounded-md border-2 transition-colors',
+                'relative h-16 w-16 flex-shrink-0 overflow-hidden rounded-md border-2 transition-colors',
                 index === selectedIndex ? 'border-primary' : 'border-transparent opacity-70 hover:opacity-100',
               )}
             >
-              <img
+              <Image
                 src={img.url}
                 alt={img.caption || `Thumbnail ${index + 1}`}
-                className="h-full w-full object-cover"
+                fill
+                sizes="64px"
+                className="object-cover"
               />
             </button>
           ))}
diff --git a/apps/web/components/search/property-card.tsx b/apps/web/components/search/property-card.tsx
index e7e6447..d1b7915 100644
--- a/apps/web/components/search/property-card.tsx
+++ b/apps/web/components/search/property-card.tsx
@@ -1,5 +1,6 @@
 'use client';
 
+import Image from 'next/image';
 import Link from 'next/link';
 import { Card, CardContent } from '@/components/ui/card';
 import { Badge } from '@/components/ui/badge';
@@ -27,75 +28,91 @@ interface PropertyCardProps {
 }
 
 export function PropertyCard({ listing, compact }: PropertyCardProps) {
+  const transactionLabel = listing.transactionType === 'SALE' ? 'Bán' : 'Cho thuê';
+  const propertyTypeLabel = PROPERTY_TYPE_LABELS[listing.property.propertyType] || listing.property.propertyType;
+
   return (
-    <Link href={`/listings/${listing.id}`}>
-      <Card className="group h-full overflow-hidden transition-shadow hover:shadow-md">
-        <div className={`relative bg-muted ${compact ? 'aspect-[16/10]' : 'aspect-[4/3]'}`}>
-          {listing.property.media.length > 0 ? (
-            <img
-              src={listing.property.media[0]?.url}
-              alt={listing.property.title}
-              className="h-full w-full object-cover transition-transform group-hover:scale-105"
-              loading="lazy"
-            />
-          ) : (
-            <div className="flex h-full items-center justify-center text-muted-foreground">
-              Chưa có ảnh
-            </div>
-          )}
-          <div className="absolute left-2 top-2 flex gap-1">
-            <Badge variant="default" className="text-xs">
-              {listing.transactionType === 'SALE' ? 'Bán' : 'Cho thuê'}
-            </Badge>
-            <Badge variant="secondary" className="text-xs">
-              {PROPERTY_TYPE_LABELS[listing.property.propertyType] || listing.property.propertyType}
-            </Badge>
-          </div>
-          {listing.property.media.length > 1 && (
-            <div className="absolute bottom-2 right-2">
-              <Badge variant="outline" className="bg-black/50 text-xs text-white border-none">
-                {listing.property.media.length} ảnh
+    <article
+      aria-label={`${listing.property.title} — ${transactionLabel} ${propertyTypeLabel}, ${formatPrice(listing.priceVND)} VNĐ`}
+    >
+      <Link href={`/listings/${listing.id}`}>
+        <Card className="group h-full overflow-hidden transition-shadow hover:shadow-md">
+          <div className={`relative bg-muted ${compact ? 'aspect-[16/10]' : 'aspect-[4/3]'}`}>
+            {listing.property.media.length > 0 ? (
+              <Image
+                src={listing.property.media[0]?.url ?? ''}
+                alt={`Ảnh bất động sản: ${listing.property.title}`}
+                fill
+                sizes="(max-width: 640px) 100vw, (max-width: 1024px) 50vw, 33vw"
+                className="object-cover transition-transform group-hover:scale-105"
+              />
+            ) : (
+              <div className="flex h-full items-center justify-center text-muted-foreground" aria-hidden="true">
+                Chưa có ảnh
+              </div>
+            )}
+            <div className="absolute left-2 top-2 flex gap-1">
+              <Badge variant="default" className="text-xs">
+                {transactionLabel}
+              </Badge>
+              <Badge variant="secondary" className="text-xs">
+                {propertyTypeLabel}
               </Badge>
             </div>
-          )}
-        </div>
-        <CardContent className="p-4">
-          <p className="text-lg font-bold text-primary">
-            {formatPrice(listing.priceVND)} VNĐ
-            {listing.transactionType === 'RENT' && listing.rentPriceMonthly && (
-              <span className="text-sm font-normal text-muted-foreground">/tháng</span>
-            )}
-          </p>
-          <h3 className="mt-1 line-clamp-1 font-medium">{listing.property.title}</h3>
-          <p className="mt-1 line-clamp-1 text-sm text-muted-foreground">
-            {listing.property.address}, {listing.property.district}, {listing.property.city}
-          </p>
-          <div className="mt-3 flex flex-wrap gap-1.5">
-            <Badge variant="secondary" className="text-xs">
-              {listing.property.areaM2} m²
-            </Badge>
-            {listing.property.bedrooms != null && (
-              <Badge variant="secondary" className="text-xs">
-                {listing.property.bedrooms} PN
-              </Badge>
-            )}
-            {listing.property.bathrooms != null && listing.property.bathrooms > 0 && (
-              <Badge variant="secondary" className="text-xs">
-                {listing.property.bathrooms} PT
-              </Badge>
-            )}
-            {listing.property.direction && (
-              <Badge variant="outline" className="text-xs">
-                Hướng {listing.property.direction === 'NORTH' ? 'Bắc' :
-                  listing.property.direction === 'SOUTH' ? 'Nam' :
-                  listing.property.direction === 'EAST' ? 'Đông' :
-                  listing.property.direction === 'WEST' ? 'Tây' :
-                  listing.property.direction}
-              </Badge>
+            {listing.property.media.length > 1 && (
+              <div className="absolute bottom-2 right-2">
+                <Badge variant="outline" className="bg-black/50 text-xs text-white border-none" aria-label={`${listing.property.media.length} ảnh`}>
+                  {listing.property.media.length} ảnh
+                </Badge>
+              </div>
             )}
           </div>
-        </CardContent>
-      </Card>
-    </Link>
+          <CardContent className="p-4">
+            <p className="text-lg font-bold text-primary">
+              {formatPrice(listing.priceVND)} VNĐ
+              {listing.transactionType === 'RENT' && listing.rentPriceMonthly && (
+                <span className="text-sm font-normal text-muted-foreground">/tháng</span>
+              )}
+            </p>
+            <h3 className="mt-1 line-clamp-1 font-medium">{listing.property.title}</h3>
+            <p className="mt-1 line-clamp-1 text-sm text-muted-foreground">
+              {listing.property.address}, {listing.property.district}, {listing.property.city}
+            </p>
+            <ul className="mt-3 flex flex-wrap gap-1.5" aria-label="Thông tin bất động sản">
+              <li>
+                <Badge variant="secondary" className="text-xs">
+                  {listing.property.areaM2} m²
+                </Badge>
+              </li>
+              {listing.property.bedrooms != null && (
+                <li>
+                  <Badge variant="secondary" className="text-xs">
+                    {listing.property.bedrooms} PN
+                  </Badge>
+                </li>
+              )}
+              {listing.property.bathrooms != null && listing.property.bathrooms > 0 && (
+                <li>
+                  <Badge variant="secondary" className="text-xs">
+                    {listing.property.bathrooms} PT
+                  </Badge>
+                </li>
+              )}
+              {listing.property.direction && (
+                <li>
+                  <Badge variant="outline" className="text-xs">
+                    Hướng {listing.property.direction === 'NORTH' ? 'Bắc' :
+                      listing.property.direction === 'SOUTH' ? 'Nam' :
+                      listing.property.direction === 'EAST' ? 'Đông' :
+                      listing.property.direction === 'WEST' ? 'Tây' :
+                      listing.property.direction}
+                  </Badge>
+                </li>
+              )}
+            </ul>
+          </CardContent>
+        </Card>
+      </Link>
+    </article>
   );
 }
diff --git a/apps/web/components/search/search-results.tsx b/apps/web/components/search/search-results.tsx
index 6a4ad8a..6d3f318 100644
--- a/apps/web/components/search/search-results.tsx
+++ b/apps/web/components/search/search-results.tsx
@@ -9,6 +9,8 @@ import type { ListingDetail, PaginatedResult } from '@/lib/listings-api';
 interface SearchResultsProps {
   result: PaginatedResult<ListingDetail> | null;
   loading: boolean;
+  error?: boolean;
+  onRetry?: () => void;
   page: number;
   sort: string;
   onPageChange: (page: number) => void;
@@ -18,6 +20,8 @@ interface SearchResultsProps {
 export function SearchResults({
   result,
   loading,
+  error,
+  onRetry,
   page,
   sort,
   onPageChange,
@@ -31,6 +35,20 @@ export function SearchResults({
     );
   }
 
+  if (error) {
+    return (
+      <div className="flex min-h-[400px] flex-col items-center justify-center gap-3 text-muted-foreground">
+        <p className="text-lg font-medium">Không thể tải kết quả tìm kiếm</p>
+        <p className="text-sm">Đã xảy ra lỗi. Vui lòng thử lại.</p>
+        {onRetry && (
+          <Button variant="outline" size="sm" onClick={onRetry}>
+            Thử lại
+          </Button>
+        )}
+      </div>
+    );
+  }
+
   if (!result || result.data.length === 0) {
     return (
       <div className="flex min-h-[400px] flex-col items-center justify-center text-muted-foreground">
diff --git a/apps/web/next.config.js b/apps/web/next.config.js
index f83dccb..3b88687 100644
--- a/apps/web/next.config.js
+++ b/apps/web/next.config.js
@@ -2,6 +2,28 @@
 const nextConfig = {
   reactStrictMode: true,
   output: 'standalone',
+  images: {
+    remotePatterns: [
+      {
+        protocol: 'https',
+        hostname: '**',
+      },
+    ],
+  },
+  async headers() {
+    return [
+      {
+        source: '/(.*)',
+        headers: [
+          { key: 'X-Content-Type-Options', value: 'nosniff' },
+          { key: 'X-Frame-Options', value: 'DENY' },
+          { key: 'X-XSS-Protection', value: '1; mode=block' },
+          { key: 'Referrer-Policy', value: 'strict-origin-when-cross-origin' },
+          { key: 'Permissions-Policy', value: 'camera=(), microphone=(), geolocation=(self)' },
+        ],
+      },
+    ];
+  },
 };
 
 module.exports = nextConfig;