diff --git a/api/server/controllers/mcpApps.js b/api/server/controllers/mcpApps.js
index 9d7fb2cbd5..ca9738fe78 100644
--- a/api/server/controllers/mcpApps.js
+++ b/api/server/controllers/mcpApps.js
@@ -75,9 +75,23 @@ const serveMCPSandbox = async (_req, res) => {
     res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
     res.setHeader('X-Content-Type-Options', 'nosniff');
     res.setHeader('Referrer-Policy', 'same-origin');
-    res.setHeader('Cross-Origin-Resource-Policy', 'same-origin');
-    res.setHeader('Content-Security-Policy', "frame-ancestors 'self'");
-    res.setHeader('X-Frame-Options', 'SAMEORIGIN');
+
+    // The MCP Apps spec requires the Host and Sandbox to have different origins for web hosts.
+    // Default to same-origin framing; when a dedicated sandbox origin is deployed, the operator
+    // lists the allowed host origin(s) so the host page can frame this sandbox cross-origin.
+    const allowedParents = (process.env.MCP_SANDBOX_FRAME_ANCESTORS || '').trim();
+    if (allowedParents) {
+      const ancestors = allowedParents
+        .split(/[\s,]+/)
+        .filter(Boolean)
+        .join(' ');
+      res.setHeader('Content-Security-Policy', `frame-ancestors 'self' ${ancestors}`);
+      res.setHeader('Cross-Origin-Resource-Policy', 'cross-origin');
+    } else {
+      res.setHeader('Content-Security-Policy', "frame-ancestors 'self'");
+      res.setHeader('Cross-Origin-Resource-Policy', 'same-origin');
+      res.setHeader('X-Frame-Options', 'SAMEORIGIN');
+    }
 
     const sandboxPath = path.resolve(
       __dirname,
diff --git a/client/src/hooks/MCP/useAppBridge.ts b/client/src/hooks/MCP/useAppBridge.ts
index ba98be4c80..43b8ca695c 100644
--- a/client/src/hooks/MCP/useAppBridge.ts
+++ b/client/src/hooks/MCP/useAppBridge.ts
@@ -85,7 +85,16 @@ export function useAppBridge(
         ) as never;
 
       bridge.onopenlink = async ({ url }) => {
-        window.open(url, '_blank', 'noopener,noreferrer');
+        try {
+          const { protocol } = new URL(url);
+          if (protocol === 'http:' || protocol === 'https:') {
+            window.open(url, '_blank', 'noopener,noreferrer');
+          } else {
+            logger.warn('[MCP App] Blocked open-link with unsupported scheme', protocol);
+          }
+        } catch {
+          logger.warn('[MCP App] Blocked malformed open-link url');
+        }
         return {};
       };
 
diff --git a/client/src/utils/mcpApps.ts b/client/src/utils/mcpApps.ts
index 78baeafefa..1efe5f166c 100644
--- a/client/src/utils/mcpApps.ts
+++ b/client/src/utils/mcpApps.ts
@@ -77,12 +77,20 @@ export async function fetchMCPResourceHtml(
   permissions?: ResourceUiMeta['permissions'];
 }> {
   const result = (await readMCPResource(serverName, uri, userId)) as {
-    contents?: Array<{ text?: string; _meta?: { ui?: ResourceUiMeta } }>;
+    contents?: Array<{ text?: string; blob?: string; _meta?: { ui?: ResourceUiMeta } }>;
   };
   const item = result?.contents?.[0];
   const uiMeta = item?._meta?.ui;
+  let html = item?.text ?? '';
+  if (!html && typeof item?.blob === 'string' && item.blob) {
+    try {
+      html = atob(item.blob);
+    } catch {
+      html = '';
+    }
+  }
   return {
-    html: item?.text ?? '',
+    html,
     csp: uiMeta?.csp,
     permissions: uiMeta?.permissions,
   };
diff --git a/packages/api/src/mcp/__tests__/parsers.test.ts b/packages/api/src/mcp/__tests__/parsers.test.ts
index 6bb6b19c17..7ca4fccce1 100644
--- a/packages/api/src/mcp/__tests__/parsers.test.ts
+++ b/packages/api/src/mcp/__tests__/parsers.test.ts
@@ -307,6 +307,25 @@ describe('formatToolContent', () => {
       expect(uiResourceArtifact?.content).toEqual(result.content);
     });
 
+    it('gives embedded ui:// resources distinct ids per tool result payload', () => {
+      const resourceIdFor = (sc: Record<string, unknown>) =>
+        formatToolContent(
+          {
+            content: [
+              {
+                type: 'resource',
+                resource: { uri: 'ui://app', mimeType: 'text/html', text: '<p>same</p>' },
+              },
+            ],
+            structuredContent: sc,
+          } as t.MCPToolCallResponse,
+          'openai',
+          { serverName: 'srv', toolName: 'do_thing' },
+        )[1]?.ui_resources?.data?.[0]?.resourceId;
+
+      expect(resourceIdFor({ a: 1 })).not.toEqual(resourceIdFor({ a: 2 }));
+    });
+
     it('should handle regular resources', () => {
       const result: t.MCPToolCallResponse = {
         content: [
diff --git a/packages/api/src/mcp/parsers.ts b/packages/api/src/mcp/parsers.ts
index 0df5c19c1b..942cb096ac 100644
--- a/packages/api/src/mcp/parsers.ts
+++ b/packages/api/src/mcp/parsers.ts
@@ -194,11 +194,14 @@ export function formatToolContent(
       const resourceText: string[] = [];
 
       if (isUiResource) {
-        const contentToHash =
+        const baseHash =
           'text' in item.resource && item.resource.text && typeof item.resource.text === 'string'
             ? item.resource.text
             : item.resource.uri;
-        const resourceId = generateResourceId(contentToHash);
+        const scKey =
+          result?.structuredContent != null ? JSON.stringify(result.structuredContent) : '';
+        const argsKey = metadata?.toolArgs != null ? JSON.stringify(metadata.toolArgs) : '';
+        const resourceId = generateResourceId(baseHash + '\x00' + scKey + '\x00' + argsKey);
         const uiResource: UIResource = {
           ...item.resource,
           resourceId,