docs(historian): #680 lane B review — QuestDB data-range lookups are partition scans, both-direction gate, all-Bad Count 0x80000401, outage-last parity test, CLAUDE.md per-sample bullet

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb/QuestDbHistorianDataSource.cs

@@ -495,7 +495,7 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
                         rows.Add(ReadBucket(reader, family));
                 }
                 // The tag's data range (earliest + latest live sample): the start/end-of-data Partial rules (#677/#680 —
-                // forward reads of an aggregate other than Average) and Count's in-range empty interval (#680); skipped
+                // any per-sample aggregate but Average, either direction) and Count's in-range empty interval (#680); skipped
                 // otherwise.
                 if (AggregateEvaluator.NeedsDataRange(aggregate, plan))
                 {

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerHistorianDataSource.cs

@@ -458,7 +458,7 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource
                     _ => SqlAggregateQueries.ActualTime(sample, aggregate == HistoryAggregateType.MaximumActualTime, plan.Reversed),
                 };
                 // Second result set: the tag's data range (earliest + latest sample) — the start/end-of-data Partial rules
-                // (#677/#680, forward reads of an aggregate other than Average) and Count's in-range empty interval (#680).
+                // (#677/#680 — any per-sample aggregate but Average, either direction) and Count's in-range empty interval (#680).
                 var needsRange = AggregateEvaluator.NeedsDataRange(aggregate, plan);
                 if (needsRange) sql += " " + SqlAggregateQueries.DataRange(sample);
                 await using var conn = await _conn.OpenAsync(cancellationToken).ConfigureAwait(false);