fix: show agent subtask

src/components/chat/hooks/useChatMessages.ts

@@ -13,6 +13,48 @@ function formatToolResultContent(content: unknown): string {
   return toolUseErrorMatch ? toolUseErrorMatch[1] : text;
 }
 
+type ParsedTaskNotification = {
+  status: string;
+  summary: string;
+  result: string;
+};
+
+/**
+ * Parses a background-agent `<task-notification>` block.
+ *
+ * The harness injects these as user-role messages when a background task stops.
+ * Newer notifications carry extra fields (`<tool-use-id>`, `<note>`, `<usage>`,
+ * and a `<result>` markdown payload) that the previous single-shot regex could
+ * not match, so the whole raw XML block leaked through as plain user text.
+ * Fields are extracted independently so the block renders as an assistant
+ * notification plus, when present, the agent's markdown result.
+ */
+function parseTaskNotification(content: string): ParsedTaskNotification | null {
+  if (!content.trimStart().startsWith('<task-notification>')) {
+    return null;
+  }
+
+  const statusMatch = /<status>([\s\S]*?)<\/status>/.exec(content);
+  const summaryMatch = /<summary>([\s\S]*?)<\/summary>/.exec(content);
+
+  let result = '';
+  const resultOpen = content.indexOf('<result>');
+  if (resultOpen !== -1) {
+    const afterOpen = content.slice(resultOpen + '<result>'.length);
+    const closeIndex = afterOpen.indexOf('</result>');
+    result =
+      closeIndex === -1
+        ? afterOpen.replace(/<\/task-notification>\s*$/, '').trim()
+        : afterOpen.slice(0, closeIndex).trim();
+  }
+
+  return {
+    status: statusMatch?.[1]?.trim() || 'completed',
+    summary: summaryMatch?.[1]?.trim() || 'Background task finished',
+    result,
+  };
+}
+
 /**
  * Convert NormalizedMessage[] from the session store into ChatMessage[]
  * that the existing UI components expect.
@@ -56,17 +98,26 @@ export function normalizedToChatMessages(messages: NormalizedMessage[]): ChatMes
 
         if (msg.role === 'user') {
           // Parse task notifications
-          const taskNotifRegex = /<task-notification>\s*<task-id>[^<]*<\/task-id>\s*<output-file>[^<]*<\/output-file>\s*<status>([^<]*)<\/status>\s*<summary>([^<]*)<\/summary>\s*<\/task-notification>/g;
-          const taskNotifMatch = taskNotifRegex.exec(content);
-          if (taskNotifMatch) {
+          const taskNotif = parseTaskNotification(content);
+          if (taskNotif) {
             converted.push({
               type: 'assistant',
-              content: taskNotifMatch[2]?.trim() || 'Background task finished',
+              content: taskNotif.summary,
               timestamp: msg.timestamp,
               isTaskNotification: true,
-              taskStatus: taskNotifMatch[1]?.trim() || 'completed',
+              taskStatus: taskNotif.status,
               ...sharedMetadata,
             });
+            // Render the agent's result as a normal assistant message so its
+            // markdown displays correctly instead of leaking raw XML.
+            if (taskNotif.result) {
+              converted.push({
+                type: 'assistant',
+                content: formatUsageLimitText(unescapeWithMathProtection(decodeHtmlEntities(taskNotif.result))),
+                timestamp: msg.timestamp,
+                ...sharedMetadata,
+              });
+            }
           } else {
             converted.push({
               type: 'user',