Shown after each step for your last post topic. The sim collects competitor posts from the last 12 simulated hours, counts how many topics overlap yours (≥50% shared words), and divides by the number of those recent competitor posts. Result is capped at 1.0. High saturation usually means more crowd overlap; the environment can lower engagement when you post into a crowded topic.

Viral probability (dashboard only): min(100, round(engagement_rate × 1000)) with LOW / MEDIUM / HIGH labels at 40% and 70%. It is not the grader and not a forecast of real-world reach.