diff --git a/apps/ui/src/components/dialogs/board-background-modal.tsx b/apps/ui/src/components/dialogs/board-background-modal.tsx
index c1acdfd9..ae6bd714 100644
--- a/apps/ui/src/components/dialogs/board-background-modal.tsx
+++ b/apps/ui/src/components/dialogs/board-background-modal.tsx
@@ -13,7 +13,8 @@ import { Label } from '@/components/ui/label';
 import { Checkbox } from '@/components/ui/checkbox';
 import { cn } from '@/lib/utils';
 import { useAppStore, defaultBackgroundSettings } from '@/store/app-store';
-import { getHttpApiClient, getServerUrlSync } from '@/lib/http-api-client';
+import { getHttpApiClient } from '@/lib/http-api-client';
+import { getAuthenticatedImageUrl } from '@/lib/api-fetch';
 import { useBoardBackgroundSettings } from '@/hooks/use-board-background-settings';
 import { toast } from 'sonner';
 import {
@@ -62,12 +63,13 @@ export function BoardBackgroundModal({ open, onOpenChange }: BoardBackgroundModa
   // Update preview image when background settings change
   useEffect(() => {
     if (currentProject && backgroundSettings.imagePath) {
-      const serverUrl = import.meta.env.VITE_SERVER_URL || getServerUrlSync();
       // Add cache-busting query parameter to force browser to reload image
-      const cacheBuster = imageVersion ? `&v=${imageVersion}` : `&v=${Date.now()}`;
-      const imagePath = `${serverUrl}/api/fs/image?path=${encodeURIComponent(
-        backgroundSettings.imagePath
-      )}&projectPath=${encodeURIComponent(currentProject.path)}${cacheBuster}`;
+      const cacheBuster = imageVersion ?? Date.now().toString();
+      const imagePath = getAuthenticatedImageUrl(
+        backgroundSettings.imagePath,
+        currentProject.path,
+        cacheBuster
+      );
       setPreviewImage(imagePath);
     } else {
       setPreviewImage(null);
diff --git a/apps/ui/src/components/ui/description-image-dropzone.tsx b/apps/ui/src/components/ui/description-image-dropzone.tsx
index 9df5e0e6..78fe0346 100644
--- a/apps/ui/src/components/ui/description-image-dropzone.tsx
+++ b/apps/ui/src/components/ui/description-image-dropzone.tsx
@@ -3,7 +3,7 @@ import { cn } from '@/lib/utils';
 import { ImageIcon, X, Loader2, FileText } from 'lucide-react';
 import { Textarea } from '@/components/ui/textarea';
 import { getElectronAPI } from '@/lib/electron';
-import { getServerUrlSync } from '@/lib/http-api-client';
+import { getAuthenticatedImageUrl } from '@/lib/api-fetch';
 import { useAppStore, type FeatureImagePath, type FeatureTextFilePath } from '@/store/app-store';
 import {
   sanitizeFilename,
@@ -94,9 +94,8 @@ export function DescriptionImageDropZone({
   // Construct server URL for loading saved images
   const getImageServerUrl = useCallback(
     (imagePath: string): string => {
-      const serverUrl = import.meta.env.VITE_SERVER_URL || getServerUrlSync();
       const projectPath = currentProject?.path || '';
-      return `${serverUrl}/api/fs/image?path=${encodeURIComponent(imagePath)}&projectPath=${encodeURIComponent(projectPath)}`;
+      return getAuthenticatedImageUrl(imagePath, projectPath);
     },
     [currentProject?.path]
   );
diff --git a/apps/ui/src/components/views/board-view/hooks/use-board-background.ts b/apps/ui/src/components/views/board-view/hooks/use-board-background.ts
index 5bd5f4f2..e61ba44c 100644
--- a/apps/ui/src/components/views/board-view/hooks/use-board-background.ts
+++ b/apps/ui/src/components/views/board-view/hooks/use-board-background.ts
@@ -1,6 +1,6 @@
 import { useMemo } from 'react';
 import { useAppStore, defaultBackgroundSettings } from '@/store/app-store';
-import { getServerUrlSync } from '@/lib/http-api-client';
+import { getAuthenticatedImageUrl } from '@/lib/api-fetch';
 
 interface UseBoardBackgroundProps {
   currentProject: { path: string; id: string } | null;
@@ -22,14 +22,14 @@ export function useBoardBackground({ currentProject }: UseBoardBackgroundProps)
       return {};
     }
 
+    const imageUrl = getAuthenticatedImageUrl(
+      backgroundSettings.imagePath,
+      currentProject.path,
+      backgroundSettings.imageVersion
+    );
+
     return {
-      backgroundImage: `url(${
-        import.meta.env.VITE_SERVER_URL || getServerUrlSync()
-      }/api/fs/image?path=${encodeURIComponent(
-        backgroundSettings.imagePath
-      )}&projectPath=${encodeURIComponent(currentProject.path)}${
-        backgroundSettings.imageVersion ? `&v=${backgroundSettings.imageVersion}` : ''
-      })`,
+      backgroundImage: `url(${imageUrl})`,
       backgroundSize: 'cover',
       backgroundPosition: 'center',
       backgroundRepeat: 'no-repeat',
diff --git a/apps/ui/src/lib/api-fetch.ts b/apps/ui/src/lib/api-fetch.ts
index fc76c266..f3df93bf 100644
--- a/apps/ui/src/lib/api-fetch.ts
+++ b/apps/ui/src/lib/api-fetch.ts
@@ -153,3 +153,37 @@ export async function apiDeleteRaw(
 ): Promise<Response> {
   return apiFetch(endpoint, 'DELETE', options);
 }
+
+/**
+ * Build an authenticated image URL for use in <img> tags or CSS background-image
+ * Adds authentication via query parameter since headers can't be set for image loads
+ *
+ * @param path - Image path
+ * @param projectPath - Project path
+ * @param version - Optional cache-busting version
+ * @returns Full URL with auth credentials
+ */
+export function getAuthenticatedImageUrl(
+  path: string,
+  projectPath: string,
+  version?: string | number
+): string {
+  const serverUrl = getServerUrl();
+  const params = new URLSearchParams({
+    path,
+    projectPath,
+  });
+
+  if (version !== undefined) {
+    params.set('v', String(version));
+  }
+
+  // Add auth credential as query param (needed for image loads that can't set headers)
+  const apiKey = getApiKey();
+  if (apiKey) {
+    params.set('apiKey', apiKey);
+  }
+  // Note: Session token auth relies on cookies which are sent automatically by the browser
+
+  return `${serverUrl}/api/fs/image?${params.toString()}`;
+}