Constant DEFAULT_LABEL_CARDINALITY_CAP

pub const DEFAULT_LABEL_CARDINALITY_CAP: usize = 4096;

Default cap on the number of distinct label-tuples retained for any one label-keyed metric. Prevents a misconfigured caller (or an attacker-controlled tenant_id) from growing the map without bound. When the cap is reached, new label-tuples are dropped and a warning is logged ONCE per metric.