Reaching a cap requires every worker in flight simultaneously, and the retry workers share an Io thread pool with the firehose reconnect and accept loops. The 16-worker default reproducibly peaks at 13-14 on a 32-core Linux box and 16 on macOS; the config is honored either way (the process logs workers 16 and all 20 candidates are attempted). Small caps saturate regardless and still assert equality. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>