fix(cli): improve spinner line clearing to prevent garbled output with prompt_toolkit

agent/display.py

@@ -182,9 +182,8 @@ class KawaiiSpinner:
             frame = self.spinner_frames[self.frame_idx % len(self.spinner_frames)]
             elapsed = time.time() - self.start_time
             line = f"  {frame} {self.message} ({elapsed:.1f}s)"
-            # Use \r + ANSI erase-to-EOL in a single write to avoid the
-            # two-phase clear+redraw that flickers under patch_stdout.
-            self._write(f"\r\033[K{line}", end='', flush=True)
+            pad = max(self.last_line_len - len(line), 0)
+            self._write(f"\r{line}{' ' * pad}", end='', flush=True)
             self.last_line_len = len(line)
             self.frame_idx += 1
             time.sleep(0.12)
@@ -204,7 +203,10 @@ class KawaiiSpinner:
         self.running = False
         if self.thread:
             self.thread.join(timeout=0.5)
-        self._write('\r\033[K', end='', flush=True)
+        # Clear the spinner line with spaces instead of \033[K to avoid
+        # garbled escape codes when prompt_toolkit's patch_stdout is active.
+        blanks = ' ' * max(self.last_line_len + 5, 40)
+        self._write(f"\r{blanks}\r", end='', flush=True)
         if final_message:
             self._write(f"  {final_message}", flush=True)