fix(historian): respect gateway ceilings and history value contracts

2026-10-13 03:51:04 -04:00
parent 66a2b0c3e9
commit 97668d26d3
15 changed files with 474 additions and 29 deletions
@@ -227,7 +227,27 @@ internal static class GatewayAtTimeReader
                {
                    if (!beforeKnown)
                    {
-                        before = await WalkBackAsync(ctx, qs, walkKnown, walkWidth).ConfigureAwait(false);
+                        // #696: prove the future stretch empty before jumping to now. Historian clocks or imports
+                        // can place real rows there; a full bounded probe seeds the original backward search.
+                        var searchEnd = qs;
+                        if (qs > now && walkKnown is null)
+                        {
+                            var future = await ReadTrustedAsync(ctx, MsFloor(now),
+                                Min(MsFloor(qs) + OneMs, horizon), ReadRows).ConfigureAwait(false);
+                            StoredSample? latest = null;
+                            foreach (var row in future.Rows)
+                                if (row.TimeUtc <= qs) latest = row;
+                            if (future.Complete)
+                            {
+                                before = latest;
+                                beforeKnown = latest is not null;
+                                searchEnd = now;
+                            }
+                            else if (latest is { } found)
+                                walkKnown = found.TimeUtc;
+                        }
+                        if (!beforeKnown)
+                            before = await WalkBackAsync(ctx, searchEnd, walkKnown, walkWidth).ConfigureAwait(false);
                        beforeKnown = true;
                    }
                    prev = before;