BOT_FIRE_CONCURRENCY (8) — pg-boss worker pool size, gates max accounts firing fan-outs in parallel. BOT_GROUP_CONCURRENCY (3) — per-account parallel group sends; parts within a group stay serial so chat order is preserved. BOT_MAX_SEND_PER_MINUTE (40) — per-account token-bucket rate. Defaults are tuned for an established WhatsApp account (~30-60 msg/min safe band). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>