MeasurementRouter.onLevelMeasurement was writing level samples via
.value(value).unit(context.unit), which dropped the timestamp. The
level-rate fallback in FlowAggregator derives netFlow from dlevel/dt,
so without a timestamp on each sample it had nothing to differentiate.
Switch to the positional .value(value, timestamp, unit) form so the
fallback works. Add a basic test that drives two level samples 2 s
apart and asserts the aggregator produces direction=filling with a
finite dlevel/dt-derived netFlow.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
a3536b7b7f