Your own message came back twice — once from the POST that sent it, once
echoed over your own SSE stream — so the felt printed it on the rail twice.
Drop any chat id already seen; reset the seen-set when the log is cleared
(unseated, and on a full chat reload).
Claude-Session: https://claude.ai/code/session_013M5nD7PgUboJXoDcYHzpuJ