Fixed-hierarchy sensor aggregation
Thousands of sensors rolling up through a fixed group hierarchy, updated by telemetry increments. Measured on Theodolite's UC4 benchmark on x86 against the stock Kafka Streams implementation of the same topology. Draining a standing backlog, HST ran 15x the baseline rate across all windows and 21x once warm. Held instead at a matched offered rate of 16,384 events per second, the same pair ran on 38% less CPU per million events and 61% less resident memory. That is a deployment result rather than a kernel one: six stages of the pipeline differ between the two arms and five are architectural — no fan-out, no per-sensor serialization, no repartition over the network, no RocksDB, no feedback topic — with the aggregate combine being the HST part. Measured instead against a competent compiled delta rather than a streaming framework, the method's envelope is 6.94x falling to 4.75x as churn rises from 0.2% to 25% of the changed set per step, on 21 sparse operators under local drift, g++ 13.3 on one x86 box. That pair is a research result from a scheduling variant, not a figure for the distributed build. This is the single most-plausible paying shape we have found.