fix: improve subagent UI display and interruption handling (#330)

Co-authored-by: Letta <noreply@letta.com>

src/cli/helpers/subagentDisplay.ts

@@ -8,7 +8,7 @@
  * Format tool count and token statistics for display
  *
  * @param toolCount - Number of tool calls
- * @param totalTokens - Total tokens used
+ * @param totalTokens - Total tokens used (0 or undefined means no data available)
  * @param isRunning - If true, shows "—" for tokens (since usage is only available at end)
  */
 export function formatStats(
@@ -16,12 +16,19 @@ export function formatStats(
   totalTokens: number,
   isRunning = false,
 ): string {
-  const tokenStr = isRunning
-    ? "—"
-    : totalTokens >= 1000
+  const toolStr = `${toolCount} tool use${toolCount !== 1 ? "s" : ""}`;
+
+  // Only show token count if we have actual data (not running and totalTokens > 0)
+  const hasTokenData = !isRunning && totalTokens > 0;
+  if (!hasTokenData) {
+    return toolStr;
+  }
+
+  const tokenStr =
+    totalTokens >= 1000
       ? `${(totalTokens / 1000).toFixed(1)}k`
       : String(totalTokens);
-  return `${toolCount} tool use${toolCount !== 1 ? "s" : ""} · ${tokenStr} tokens`;
+  return `${toolStr} · ${tokenStr} tokens`;
 }
 
 /**