Constant MAX_RISK_DELTA 

pub const MAX_RISK_DELTA: f64 = 0.20;

Documented upper bound for any single per-key risk-score adjustment the challenge memory can apply.

The default is 0.20 (twenty percent of the risk-score range). This conservative ceiling is the key safety property of the feedback loop: a single transient outcome can never move the policy into a fundamentally different strategy band. Callers may lower the clamp via ChallengeFeedbackPolicy::with_max_delta but the value is hard-capped at MAX_RISK_DELTA to prevent runaway escalation.