EXPONENTIAL_HISTOGRAM

A distribution of measurements answering quantile queries (e.g. p50/p99 latency).

Backed by a us.tractat.kuilt.crdt.DDSketch. Every quantile estimate is within the sketch's relative accuracy α; the merge is lossless, so two replicas' sketches combine into exactly the sketch of the combined stream. Exports as an OTLP ExponentialHistogramDataPoint — the sketch's α must be OTLP-aligned via alphaForOtlpScale (the exporter enforces this).