Aggregation & rolling windows

Raw streams can be noisy or too fast to plot usefully. Aggregation rolls points into one value per interval.

• Set an aggregation function (mean, min, max, sum) and an interval on a widget's source.
• The widget buffers raw points for the interval, then emits the aggregate — repeating every interval.
• One aggregate of the loaded history is shown immediately so the widget isn't blank on load.

Use a longer interval to smooth trends; use max to catch spikes you'd otherwise miss between samples. For long ranges, combine with the rs485-query source for server-side bucketing.