diff --git a/frontend/src/components/ListingDetail.tsx b/frontend/src/components/ListingDetail.tsx
index 4a5d2d0..2b008f5 100644
--- a/frontend/src/components/ListingDetail.tsx
+++ b/frontend/src/components/ListingDetail.tsx
@@ -214,8 +214,12 @@ export function ListingDetail({ detail, onDecide, onClearDecision }: ListingDeta
               <div className="space-y-2">
                 {detail.price_history.map((entry) => (
                   <div key={entry.id} className="flex justify-between items-center text-sm py-1.5 border-b last:border-0">
-                    <span className="text-muted-foreground">{entry.last_seen.split('T')[0]}</span>
-                    <span className="font-medium">£{entry.price.toLocaleString()}</span>
+                    <span className="text-muted-foreground">
+                      {typeof entry.last_seen === 'string' ? entry.last_seen.split('T')[0] : '—'}
+                    </span>
+                    <span className="font-medium">
+                      £{typeof entry.price === 'number' && Number.isFinite(entry.price) ? entry.price.toLocaleString() : '—'}
+                    </span>
                   </div>
                 ))}
               </div>
diff --git a/frontend/src/components/PropertyCard.tsx b/frontend/src/components/PropertyCard.tsx
index dd4d9bf..663b088 100644
--- a/frontend/src/components/PropertyCard.tsx
+++ b/frontend/src/components/PropertyCard.tsx
@@ -145,8 +145,18 @@ export function PropertyCard({
     allPOIs,
     onClick,
 }: PropertyCardProps) {
-    const lastSeenDate = property.last_seen.split('T')[0];
-    const lastSeenDays = Math.round((Date.now() - new Date(lastSeenDate).getTime()) / (1000 * 60 * 60 * 24));
+    // BUY listings may have null numeric / date fields; coerce so renders don't throw.
+    const lastSeenRaw = property.last_seen;
+    const lastSeenDate = typeof lastSeenRaw === 'string' ? lastSeenRaw.split('T')[0] : null;
+    const lastSeenTime = lastSeenDate ? new Date(lastSeenDate).getTime() : NaN;
+    const lastSeenDays = Number.isFinite(lastSeenTime)
+        ? Math.round((Date.now() - lastSeenTime) / (1000 * 60 * 60 * 24))
+        : null;
+    const safeNum = (v: unknown): number => (typeof v === 'number' && Number.isFinite(v) ? v : 0);
+    const safeTotalPrice = safeNum(property.total_price);
+    const safeQm = safeNum(property.qm);
+    const safeQmprice = safeNum(property.qmprice);
+    const safeRooms = safeNum(property.rooms);
 
     // Determine if this is a good deal
     const isGoodDeal = avgPricePerSqm && property.qmprice > 0 && property.qmprice < avgPricePerSqm * 0.9;
@@ -175,7 +185,7 @@ export function PropertyCard({
                     {(property.photos?.length || property.photo_thumbnail) ? (
                         <CardCarousel
                             photos={property.photos?.length ? property.photos : [property.photo_thumbnail]}
-                            altText={`${property.rooms}-bed, ${property.qm}m², £${property.total_price.toLocaleString()}`}
+                            altText={`${safeRooms}-bed, ${safeQm}m², £${safeTotalPrice.toLocaleString()}`}
                         />
                     ) : null}
                 </div>
@@ -185,7 +195,7 @@ export function PropertyCard({
                     {/* Price */}
                     <div className="flex items-center gap-1.5">
                         <span className="text-lg font-bold tracking-tight">
-                            £{property.total_price.toLocaleString()}
+                            £{safeTotalPrice.toLocaleString()}
                             {property.listing_type !== 'BUY' && (
                                 <span className="text-muted-foreground font-normal text-sm">/mo</span>
                             )}
@@ -200,18 +210,22 @@ export function PropertyCard({
 
                     {/* Key metrics on one line */}
                     <div className="flex items-center gap-1 text-sm text-muted-foreground mt-0.5">
-                        <span>{property.rooms}</span><span>bed</span>
+                        <span>{safeRooms}</span><span>bed</span>
                         <span>·</span>
-                        <span>{property.qm} m²</span>
+                        <span>{safeQm} m²</span>
                         <span>·</span>
-                        <span>£{property.qmprice}/m²</span>
+                        <span>£{safeQmprice}/m²</span>
                     </div>
 
                     {/* Agency + freshness */}
                     <div className="flex items-center gap-1 text-xs text-muted-foreground mt-1">
                         <span>{property.agency}</span>
-                        <span>·</span>
-                        <span>{lastSeenDays}d ago</span>
+                        {lastSeenDays !== null && (
+                            <>
+                                <span>·</span>
+                                <span>{lastSeenDays}d ago</span>
+                            </>
+                        )}
                     </div>
 
                     {/* POI badges */}
@@ -234,7 +248,7 @@ export function PropertyCard({
                 {(property.photos?.length || property.photo_thumbnail) ? (
                     <CardCarousel
                         photos={property.photos?.length ? property.photos : [property.photo_thumbnail]}
-                        altText={`${property.rooms}-bed, ${property.qm}m², £${property.total_price.toLocaleString()}`}
+                        altText={`${safeRooms}-bed, ${safeQm}m², £${safeTotalPrice.toLocaleString()}`}
                     />
                 ) : null}
 
@@ -257,7 +271,7 @@ export function PropertyCard({
                 {/* Price as dominant element */}
                 <div className="flex items-center gap-1.5">
                     <span className="text-lg font-bold tracking-tight">
-                        £{property.total_price.toLocaleString()}
+                        £{safeTotalPrice.toLocaleString()}
                         {property.listing_type !== 'BUY' && (
                             <span className="text-muted-foreground font-normal text-sm">/mo</span>
                         )}
@@ -272,11 +286,11 @@ export function PropertyCard({
 
                 {/* Key metrics on one line */}
                 <div className="flex items-center gap-1 text-sm text-muted-foreground">
-                    <span>{property.rooms}</span><span>bed</span>
+                    <span>{safeRooms}</span><span>bed</span>
                     <span>·</span>
-                    <span>{property.qm} m²</span>
+                    <span>{safeQm} m²</span>
                     <span>·</span>
-                    <span>£{property.qmprice}/m²</span>
+                    <span>£{safeQmprice}/m²</span>
                 </div>
 
                 {/* Location */}
@@ -294,8 +308,12 @@ export function PropertyCard({
                 {/* Agency + freshness */}
                 <div className="flex items-center gap-1 text-xs text-muted-foreground">
                     <span>{property.agency}</span>
-                    <span>·</span>
-                    <span>{lastSeenDays}d ago</span>
+                    {lastSeenDays !== null && (
+                        <>
+                            <span>·</span>
+                            <span>{lastSeenDays}d ago</span>
+                        </>
+                    )}
                 </div>
             </div>
         </div>
diff --git a/frontend/src/components/PropertyCardCompact.tsx b/frontend/src/components/PropertyCardCompact.tsx
index 685734a..f6d0d99 100644
--- a/frontend/src/components/PropertyCardCompact.tsx
+++ b/frontend/src/components/PropertyCardCompact.tsx
@@ -16,8 +16,15 @@ export function PropertyCardCompact({
     avgPricePerSqm,
     onClick,
 }: PropertyCardCompactProps) {
-    const isGoodDeal = avgPricePerSqm && property.qmprice > 0 && property.qmprice < avgPricePerSqm * 0.9;
-    const isExpensive = avgPricePerSqm && property.qmprice > avgPricePerSqm * 1.1;
+    // BUY listings may have null numeric fields; coerce so renders don't throw.
+    const safeNum = (v: unknown): number => (typeof v === 'number' && Number.isFinite(v) ? v : 0);
+    const safeTotalPrice = safeNum(property.total_price);
+    const safeQm = safeNum(property.qm);
+    const safeQmprice = safeNum(property.qmprice);
+    const safeRooms = safeNum(property.rooms);
+
+    const isGoodDeal = avgPricePerSqm && safeQmprice > 0 && safeQmprice < avgPricePerSqm * 0.9;
+    const isExpensive = avgPricePerSqm && safeQmprice > avgPricePerSqm * 1.1;
 
     const priceIndicator = isGoodDeal
         ? { dotColor: 'bg-[var(--deal-good)]', label: 'Good deal' }
@@ -37,7 +44,7 @@ export function PropertyCardCompact({
                 {property.photo_thumbnail && (
                     <img
                         src={property.photo_thumbnail}
-                        alt={`${property.rooms}-bed, £${property.total_price.toLocaleString()}`}
+                        alt={`${safeRooms}-bed, £${safeTotalPrice.toLocaleString()}`}
                         className="w-full h-full object-cover"
                     />
                 )}
@@ -48,7 +55,7 @@ export function PropertyCardCompact({
                 {/* Price bold */}
                 <div className="flex items-center gap-1.5">
                     <span className="font-bold text-base">
-                        £{property.total_price.toLocaleString()}
+                        £{safeTotalPrice.toLocaleString()}
                         {property.listing_type !== 'BUY' && (
                             <span className="text-muted-foreground font-normal text-sm">/mo</span>
                         )}
@@ -62,10 +69,10 @@ export function PropertyCardCompact({
                 <div className="flex items-center gap-2 text-sm text-muted-foreground">
                     <span className="flex items-center gap-1">
                         <Bed className="h-3.5 w-3.5" />
-                        {property.rooms} bed
+                        {safeRooms} bed
                     </span>
                     <span>·</span>
-                    <span>{property.qm} m²</span>
+                    <span>{safeQm} m²</span>
                 </div>
 
                 {/* Location */}
diff --git a/frontend/src/components/SwipeCard.tsx b/frontend/src/components/SwipeCard.tsx
index c9883f6..e080fef 100644
--- a/frontend/src/components/SwipeCard.tsx
+++ b/frontend/src/components/SwipeCard.tsx
@@ -19,6 +19,12 @@ export function SwipeCard({ feature, onSwipe, onTap, isTop, stackIndex }: SwipeC
   const hasSwiped = useRef(false);
   const p = feature.properties;
   const photos = p.photos?.length ? p.photos : p.photo_thumbnail ? [p.photo_thumbnail] : [];
+  // BUY listings may have null numeric fields; coerce so renders don't throw.
+  const safeNum = (v: unknown): number => (typeof v === 'number' && Number.isFinite(v) ? v : 0);
+  const safeTotalPrice = safeNum(p.total_price);
+  const safeQm = safeNum(p.qm);
+  const safeQmprice = safeNum(p.qmprice);
+  const safeRooms = safeNum(p.rooms);
 
   const prefersReducedMotion = useMemo(
     () => window.matchMedia('(prefers-reduced-motion: reduce)').matches,
@@ -150,7 +156,7 @@ export function SwipeCard({ feature, onSwipe, onTap, isTop, stackIndex }: SwipeC
               </div>
             </>
           ) : photos.length === 1 ? (
-            <img src={photos[0]} alt={`${p.rooms}-bed, ${p.qm}m², £${p.total_price.toLocaleString()}`} className="w-full h-full object-cover" />
+            <img src={photos[0]} alt={`${safeRooms}-bed, ${safeQm}m², £${safeTotalPrice.toLocaleString()}`} className="w-full h-full object-cover" />
           ) : null}
           <button
             className="absolute top-3 right-3 bg-background/80 backdrop-blur-sm rounded-full p-2 z-20"
@@ -171,7 +177,7 @@ export function SwipeCard({ feature, onSwipe, onTap, isTop, stackIndex }: SwipeC
         >
           {/* Price */}
           <div className="text-2xl font-semibold">
-            £{p.total_price.toLocaleString()}
+            £{safeTotalPrice.toLocaleString()}
             {p.listing_type !== 'BUY' && (
               <span className="text-muted-foreground font-normal text-base">/mo</span>
             )}
@@ -180,12 +186,12 @@ export function SwipeCard({ feature, onSwipe, onTap, isTop, stackIndex }: SwipeC
           {/* Key stats */}
           <div className="flex items-center gap-4 text-sm text-muted-foreground">
             <span className="flex items-center gap-1">
-              <Bed className="h-4 w-4" /> {p.rooms} bed
+              <Bed className="h-4 w-4" /> {safeRooms} bed
             </span>
             <span className="flex items-center gap-1">
-              <Maximize2 className="h-4 w-4" /> {p.qm} m²
+              <Maximize2 className="h-4 w-4" /> {safeQm} m²
             </span>
-            <span>£{p.qmprice}/m²</span>
+            <span>£{safeQmprice}/m²</span>
           </div>
 
           {/* Agency & availability */}
diff --git a/frontend/src/components/__tests__/PropertyCard.test.tsx b/frontend/src/components/__tests__/PropertyCard.test.tsx
index 676b184..ec6043f 100644
--- a/frontend/src/components/__tests__/PropertyCard.test.tsx
+++ b/frontend/src/components/__tests__/PropertyCard.test.tsx
@@ -2,6 +2,7 @@ import { render, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { PropertyCard } from '@/components/PropertyCard';
 import { createMockProperty } from '@/__tests__/helpers';
+import type { PropertyProperties } from '@/types';
 
 describe('PropertyCard', () => {
   it('renders rent price with /mo suffix', () => {
@@ -88,4 +89,35 @@ describe('PropertyCard', () => {
     const { container } = render(<PropertyCard property={property} isHighlighted />);
     expect(container.querySelector('.ring-2')).toBeInTheDocument();
   });
+
+  it('renders without crashing when BUY listing has null numeric/date fields', () => {
+    // Regression: backend returns null for total_price/qm/qmprice/rooms/last_seen on some BUY listings.
+    const partial = {
+      ...createMockProperty({ listing_type: 'BUY' }),
+      total_price: null,
+      qm: null,
+      qmprice: null,
+      rooms: null,
+      last_seen: null,
+    } as unknown as PropertyProperties;
+
+    expect(() => render(<PropertyCard property={partial} />)).not.toThrow();
+    expect(screen.queryByText(/NaN/)).not.toBeInTheDocument();
+    expect(screen.queryByText(/d ago/)).not.toBeInTheDocument();
+  });
+
+  it('renders full variant without crashing when BUY listing has null fields', () => {
+    const partial = {
+      ...createMockProperty({ listing_type: 'BUY' }),
+      total_price: null,
+      qm: null,
+      qmprice: null,
+      rooms: null,
+      last_seen: null,
+    } as unknown as PropertyProperties;
+
+    expect(() => render(<PropertyCard property={partial} variant="full" />)).not.toThrow();
+    expect(screen.queryByText(/NaN/)).not.toBeInTheDocument();
+    expect(screen.queryByText(/d ago/)).not.toBeInTheDocument();
+  });
 });
diff --git a/frontend/tsconfig.app.tsbuildinfo b/frontend/tsconfig.app.tsbuildinfo
index ae7d696..2c80063 100644
--- a/frontend/tsconfig.app.tsbuildinfo
+++ b/frontend/tsconfig.app.tsbuildinfo
@@ -1 +1 @@
-{"root":["./src/app.tsx","./src/main.tsx","./src/vite-env.d.ts","./src/auth/authservice.ts","./src/auth/config.ts","./src/auth/errors.ts","./src/auth/passkeyservice.ts","./src/auth/types.ts","./src/components/alerterror.tsx","./src/components/authcallback.tsx","./src/components/errorboundary.tsx","./src/components/favoritesview.tsx","./src/components/filterbar.tsx","./src/components/filterchips.tsx","./src/components/filterpanel.tsx","./src/components/header.tsx","./src/components/healthindicator.tsx","./src/components/listview.tsx","./src/components/listingdetail.tsx","./src/components/listingdetailsheet.tsx","./src/components/loginmodal.tsx","./src/components/map.tsx","./src/components/mobilebottomsheet.tsx","./src/components/mobilemenu.tsx","./src/components/poimanager.tsx","./src/components/photocarousel.tsx","./src/components/propertycard.tsx","./src/components/propertycardcompact.tsx","./src/components/spinner.tsx","./src/components/statsbar.tsx","./src/components/streamingprogressbar.tsx","./src/components/swipecard.tsx","./src/components/swipereviewmode.tsx","./src/components/swipeablecardrow.tsx","./src/components/swipeablepropertycard.tsx","./src/components/taskindicator.tsx","./src/components/taskprogressdrawer.tsx","./src/components/visualizationcard.tsx","./src/components/ui/datepicker.tsx","./src/components/ui/accordion.tsx","./src/components/ui/alert-dialog.tsx","./src/components/ui/breadcrumb.tsx","./src/components/ui/button.tsx","./src/components/ui/calendar.tsx","./src/components/ui/checkbox.tsx","./src/components/ui/dialog.tsx","./src/components/ui/form.tsx","./src/components/ui/hover-card.tsx","./src/components/ui/input.tsx","./src/components/ui/label.tsx","./src/components/ui/popover.tsx","./src/components/ui/progress.tsx","./src/components/ui/range-slider-field.tsx","./src/components/ui/scroll-area.tsx","./src/components/ui/select.tsx","./src/components/ui/separator.tsx","./src/components/ui/sheet.tsx","./src/components/ui/sidebar.tsx","./src/components/ui/skeleton.tsx","./src/components/ui/slider.tsx","./src/components/ui/tabs.tsx","./src/components/ui/tooltip.tsx","./src/constants/colorschemes.ts","./src/constants/index.ts","./src/hooks/use-mobile.ts","./src/hooks/usedecisions.ts","./src/hooks/usefilterparams.ts","./src/hooks/uselistingdetail.ts","./src/hooks/usetaskprogress.ts","./src/lib/utils.ts","./src/services/apiclient.ts","./src/services/decisionservice.ts","./src/services/healthservice.ts","./src/services/index.ts","./src/services/listingcache.ts","./src/services/listingdetailservice.ts","./src/services/listingservice.ts","./src/services/perfcollector.ts","./src/services/poiservice.ts","./src/services/streamingservice.ts","./src/services/taskservice.ts","./src/types/index.ts","./src/utils/format.ts","./src/utils/maputils.ts","./src/utils/poiutils.ts","./src/utils/taskutils.ts","./src/workers/hexgridheatmapclient.ts","./src/workers/hexgrid.worker.ts","./src/workers/types.ts"],"version":"5.8.3"}
\ No newline at end of file
+{"root":["./src/App.tsx","./src/main.tsx","./src/vite-env.d.ts","./src/auth/authService.ts","./src/auth/config.ts","./src/auth/errors.ts","./src/auth/passkeyService.ts","./src/auth/types.ts","./src/components/AlertError.tsx","./src/components/AuthCallback.tsx","./src/components/ErrorBoundary.tsx","./src/components/FavoritesView.tsx","./src/components/FilterBar.tsx","./src/components/FilterChips.tsx","./src/components/FilterPanel.tsx","./src/components/Header.tsx","./src/components/HealthIndicator.tsx","./src/components/ListView.tsx","./src/components/ListingDetail.tsx","./src/components/ListingDetailSheet.tsx","./src/components/LoginModal.tsx","./src/components/Map.tsx","./src/components/MobileBottomSheet.tsx","./src/components/MobileMenu.tsx","./src/components/POIManager.tsx","./src/components/PhotoCarousel.tsx","./src/components/PropertyCard.tsx","./src/components/PropertyCardCompact.tsx","./src/components/Spinner.tsx","./src/components/StatsBar.tsx","./src/components/StreamingProgressBar.tsx","./src/components/SwipeCard.tsx","./src/components/SwipeReviewMode.tsx","./src/components/SwipeableCardRow.tsx","./src/components/SwipeablePropertyCard.tsx","./src/components/TaskIndicator.tsx","./src/components/TaskProgressDrawer.tsx","./src/components/VisualizationCard.tsx","./src/components/ui/DatePicker.tsx","./src/components/ui/accordion.tsx","./src/components/ui/alert-dialog.tsx","./src/components/ui/breadcrumb.tsx","./src/components/ui/button.tsx","./src/components/ui/calendar.tsx","./src/components/ui/checkbox.tsx","./src/components/ui/dialog.tsx","./src/components/ui/form.tsx","./src/components/ui/hover-card.tsx","./src/components/ui/input.tsx","./src/components/ui/label.tsx","./src/components/ui/popover.tsx","./src/components/ui/progress.tsx","./src/components/ui/range-slider-field.tsx","./src/components/ui/scroll-area.tsx","./src/components/ui/select.tsx","./src/components/ui/separator.tsx","./src/components/ui/sheet.tsx","./src/components/ui/sidebar.tsx","./src/components/ui/skeleton.tsx","./src/components/ui/slider.tsx","./src/components/ui/tabs.tsx","./src/components/ui/tooltip.tsx","./src/constants/colorSchemes.ts","./src/constants/index.ts","./src/hooks/use-mobile.ts","./src/hooks/useDecisions.ts","./src/hooks/useFilterParams.ts","./src/hooks/useListingDetail.ts","./src/hooks/useTaskProgress.ts","./src/lib/utils.ts","./src/services/apiClient.ts","./src/services/decisionService.ts","./src/services/healthService.ts","./src/services/index.ts","./src/services/listingCache.ts","./src/services/listingDetailService.ts","./src/services/listingService.ts","./src/services/perfCollector.ts","./src/services/poiService.ts","./src/services/streamingService.ts","./src/services/taskService.ts","./src/types/index.ts","./src/utils/format.ts","./src/utils/mapUtils.ts","./src/utils/poiUtils.ts","./src/utils/taskUtils.ts","./src/workers/HexgridHeatmapClient.ts","./src/workers/hexgrid.worker.ts","./src/workers/types.ts"],"version":"5.8.3"}
\ No newline at end of file