Summarise the errors matching a filter, across the whole window.

Returns total, the number of distinct sessions and agents involved, last_ts (null when nothing matched), a bins array of exactly 24 counts, and the bounds in epoch milliseconds that those bins span.

Two things to know. The result is ALWAYS restricted to errored events, so it is not a general event rollup — the same filters here and on /events/summary?errored=true describe the same set, which is what keeps a chart and its rows in agreement. And when ts_from/ts_to are omitted, the bins span the matched data’s own first and last event rather than a fixed window, so bounds is the only reliable way to turn a bin index back into a time range. Counts are computed over the entire window, not the current page, and are cached for about ten seconds.