diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/SessionIndexFieldManifestTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/SessionIndexFieldManifestTests.cs
index 6a159402..d63375ac 100644
--- a/src/Backend/AutopilotMonitor.Functions.Tests/SessionIndexFieldManifestTests.cs
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/SessionIndexFieldManifestTests.cs
@@ -90,6 +90,7 @@ public class SessionIndexFieldManifestTests
         ["DiagnosticsBlobName"] = "diag-0001.zip",
         ["DiagnosticsBlobDestination"] = "Hosted",
         ["LastEventAt"] = new DateTimeOffset(StartedAt.AddMinutes(44)),
+        ["LastIngestAt"] = new DateTimeOffset(StartedAt.AddMinutes(46)),
         ["ResumedAt"] = new DateTimeOffset(StartedAt.AddMinutes(10)),
         ["StalledAt"] = new DateTimeOffset(StartedAt.AddMinutes(20)),
         ["AvgApiLatencyMs"] = 513.5,
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/SessionIndexFieldManifest.cs b/src/Backend/AutopilotMonitor.Functions/Services/SessionIndexFieldManifest.cs
index f3e8bdf0..e7921fec 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/SessionIndexFieldManifest.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/SessionIndexFieldManifest.cs
@@ -78,6 +78,7 @@ namespace AutopilotMonitor.Functions.Services
             "DiagnosticsBlobName",
             "DiagnosticsBlobDestination",
             "LastEventAt",
+            "LastIngestAt",
             "ResumedAt",
             "StalledAt",
             "AvgApiLatencyMs",
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Sessions.cs b/src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Sessions.cs
index ffea48ed..8fc6872f 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Sessions.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Sessions.cs
@@ -225,6 +225,13 @@ namespace AutopilotMonitor.Functions.Services
             if (lastEventAt.HasValue)
                 indexEntity["LastEventAt"] = EnsureUtc(lastEventAt.Value);
 
+            // Server-frame ingest stamp (IncrementSessionEventCountAsync merges this on every
+            // batch, so the index already carries it) — must be in this superset or a
+            // StartedAt-shift full upsert drops it and index-served reads lose the field.
+            var lastIngestAt = sessionEntity.GetDateTimeOffset("LastIngestAt")?.UtcDateTime;
+            if (lastIngestAt.HasValue)
+                indexEntity["LastIngestAt"] = EnsureUtc(lastIngestAt.Value);
+
             var resumedAt = sessionEntity.GetDateTimeOffset("ResumedAt")?.UtcDateTime;
             if (resumedAt.HasValue)
                 indexEntity["ResumedAt"] = EnsureUtc(resumedAt.Value);