One argv string is capped at MAX_ARG_STRLEN (131,072 bytes on Linux), so a prompt passed as --prompt could not reach the registry once it carried a large diff. submit now takes --prompt-file and passes the same path to `registry.py register --prompt-file`; the loop type's per-iteration update goes by file too. --prompt keeps working unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>