From b1fa8221ef8f7e3248d2a8e61262decbfc997762 Mon Sep 17 00:00:00 2001
From: Dustin Healy <54083382+dustinhealy@users.noreply.github.com>
Date: Tue, 23 Jun 2026 16:39:58 -0700
Subject: [PATCH] fix(mcp): fix three correctness issues from Codex review

parsers.ts: the early-return guard for empty content was firing before the
synthetic UIResource block, so tools returning only structuredContent (no
content items) never produced an app resource. Now the guard skips the early
return when a synthetic app is expected. Also, the synthetic block was not
appending the \ui{resourceId} marker to the text, leaving the LLM without an
ID to place; fixed by mirroring the marker lines that the non-synthetic
resource handler already emits.

ToolCall / MCPUIResource: "Loading interactive view..." was a hardcoded
string; replaced with com_ui_loading_interactive_view from the localization
layer in both components, per project convention.
---
 client/src/components/Chat/Messages/Content/ToolCall.tsx | 3 ++-
 client/src/components/MCPUIResource/MCPUIResource.tsx    | 2 +-
 client/src/locales/en/translation.json                   | 1 +
 packages/api/src/mcp/parsers.ts                          | 7 ++++++-
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/client/src/components/Chat/Messages/Content/ToolCall.tsx b/client/src/components/Chat/Messages/Content/ToolCall.tsx
index a713d60da2..dc95a98722 100644
--- a/client/src/components/Chat/Messages/Content/ToolCall.tsx
+++ b/client/src/components/Chat/Messages/Content/ToolCall.tsx
@@ -29,6 +29,7 @@ const MCPAppView = React.memo(function MCPAppView({
   app: UIResource;
   args: string | Record<string, unknown>;
 }) {
+  const localize = useLocalize();
   const iframeRef = useRef<HTMLIFrameElement>(null);
   const [height, setHeight] = useState<number | undefined>(undefined);
   const [loaded, setLoaded] = useState(false);
@@ -82,7 +83,7 @@ const MCPAppView = React.memo(function MCPAppView({
               d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z"
             />
           </svg>
-          Loading interactive view...
+          {localize('com_ui_loading_interactive_view')}
         </div>
       )}
       <iframe
diff --git a/client/src/components/MCPUIResource/MCPUIResource.tsx b/client/src/components/MCPUIResource/MCPUIResource.tsx
index b65812636d..84e0f28d87 100644
--- a/client/src/components/MCPUIResource/MCPUIResource.tsx
+++ b/client/src/components/MCPUIResource/MCPUIResource.tsx
@@ -57,7 +57,7 @@ export function MCPUIResource(props: MCPUIResourceProps) {
         <span className="mx-1 inline-block w-full align-middle">
           {!loaded && (
             <div className="flex items-center gap-2 rounded-lg border border-border-light bg-surface-secondary px-4 py-3 text-sm text-text-secondary">
-              Loading interactive view...
+              {localize('com_ui_loading_interactive_view')}
             </div>
           )}
           <iframe
diff --git a/client/src/locales/en/translation.json b/client/src/locales/en/translation.json
index 27036505c5..5440779c8e 100644
--- a/client/src/locales/en/translation.json
+++ b/client/src/locales/en/translation.json
@@ -1199,6 +1199,7 @@
   "com_ui_live": "live",
   "com_ui_load_more": "Load more",
   "com_ui_loading": "Loading...",
+  "com_ui_loading_interactive_view": "Loading interactive view...",
   "com_ui_locked": "Locked",
   "com_ui_logo": "{{0}} Logo",
   "com_ui_low": "Low",
diff --git a/packages/api/src/mcp/parsers.ts b/packages/api/src/mcp/parsers.ts
index 2e4d8ab9f8..bd9544f40b 100644
--- a/packages/api/src/mcp/parsers.ts
+++ b/packages/api/src/mcp/parsers.ts
@@ -154,7 +154,9 @@ export function formatToolContent(
   }
 
   const content = result?.content ?? [];
-  if (!content.length) {
+  const hasSyntheticApp =
+    metadata?.resourceUri != null && metadata.serverName != null && metadata.toolName != null;
+  if (!content.length && !hasSyntheticApp) {
     return ['(No response)', undefined];
   }
 
@@ -253,6 +255,9 @@ export function formatToolContent(
       csp: metadata.csp,
       permissions: metadata.permissions,
     });
+    currentTextBlock +=
+      (currentTextBlock ? '\n\n' : '') +
+      `UI Resource ID: ${resourceId}\nUI Resource Marker: \\ui{${resourceId}}`;
   }
 
   if (uiResources.length > 0) {