milestone 30: overview as a dashboard, explicit health contract, period aggregations

src/upstream/health.zig

@@ -45,10 +45,7 @@ pub const Config = struct {
 /// `State.window`.
 pub const window_len = 32;
 
-/// Bytes kept of an `@errorName`, truncated to fit. Shared rather than repeated:
-/// `history.Accumulator.Cell` and `upstream_history_repo.WindowStats` carry the
-/// same name through the minute aggregates, and three buffers of three different
-/// sizes would truncate one error name three ways.
+/// Bytes kept of an `@errorName`, truncated to fit.
 pub const error_name_capacity = 48;
 
 /// The shift is capped so `base_backoff_ms << shift` cannot run away; by then