fix(rectification): keep offer-message defined through next build

Boolean() does not narrow find(), so Docker next build failed typecheck on the selection-card key.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/rectification-agentic-chat.tsx

@@ -549,7 +549,7 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
       && Boolean(message.turnId)
       && Boolean(message.text)
     ))?.renderKey;
-  const latestOfferMessageKey = [...messages]
+  const latestOfferMessage = [...messages]
     .reverse()
     .find((message) => (
       message.role === "assistant"
@@ -559,12 +559,14 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
     ));
   const showSelectionCards = Boolean(
     candidateResult?.selectionAllowed
-    && latestOfferMessageKey
-    && turnOfferedSelection(latestOfferMessageKey)
+    && latestOfferMessage
+    && turnOfferedSelection(latestOfferMessage)
     && !busy
     && regeneratingMessageKey === null,
   );
-  const selectionCardMessageKey = showSelectionCards ? latestOfferMessageKey.renderKey : undefined;
+  const selectionCardMessageKey = showSelectionCards && latestOfferMessage
+    ? latestOfferMessage.renderKey
+    : undefined;
   const canSend = !busy && !readonly && !regeneratingMessageKey;
 
   return (