Merge master into feat/677-aggregates

# Conflicts:
#	docs/Historian.md

tests/Drivers/Historian.Conformance/EventReadConformance.cs

@@ -0,0 +1,106 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Conformance;
+
+/// <summary>
+///     The direction-aware event read (Gitea #675): forward is <c>[lo, hi)</c> ascending by <c>(EventTimeUtc, EventId)</c>;
+///     reverse is the Part 11 reverse window <c>(lo, hi]</c> DESCENDING by the same key, so a capped reverse read returns the
+///     LATEST events and flags truncation. Paging a reverse read the way the server does — resume at the last returned
+///     time inclusive and drop the boundary ties already emitted — must visit every event exactly once, newest-first,
+///     through a same-timestamp tie cluster.
+/// </summary>
+public abstract class EventReadConformance : ConformanceBase
+{
+    private static readonly CancellationToken Ct = CancellationToken.None;
+
+    /// <summary>e0@0, e1@1, then the ties t0..t4@2, then e5@3 and e6@4 (all source "s"), plus o0@2 from another source.</summary>
+    private async Task<IHistorianDataSource> SeedAsync()
+    {
+        await B.SeedEventsAsync(
+            (At(0), "e0", "s"), (At(1), "e1", "s"),
+            (At(2), "t0", "s"), (At(2), "t1", "s"), (At(2), "t2", "s"), (At(2), "t3", "s"), (At(2), "t4", "s"),
+            (At(3), "e5", "s"), (At(4), "e6", "s"),
+            (At(2), "o0", "other"));
+        return B.CreateDataSource();
+    }
+
+    private static readonly string[] NewestFirst = ["e6", "e5", "t4", "t3", "t2", "t1", "t0", "e1", "e0"];
+
+    [Fact]
+    public async Task Reverse_read_is_newest_first_by_time_then_EventId_descending()
+    {
+        using var src = await SeedAsync();
+        var r = await src.ReadEventsAsync("s", At(-1), At(10), 0, reverse: true, Ct);
+        r.Events.Select(e => e.EventId).ShouldBe(NewestFirst);
+        r.ContinuationPoint.ShouldBeNull();
+    }
+
+    [Fact]
+    public async Task Reverse_window_is_end_exclusive_start_inclusive_whichever_order_the_bounds_come_in()
+    {
+        using var src = await SeedAsync();
+        // (At(1), At(3)]: e1 at the lower bound is excluded, e5 at the upper bound included.
+        (await src.ReadEventsAsync("s", At(3), At(1), 0, reverse: true, Ct)).Events.Select(e => e.EventId)
+            .ShouldBe(["e5", "t4", "t3", "t2", "t1", "t0"]);
+        (await src.ReadEventsAsync("s", At(1), At(3), 0, reverse: true, Ct)).Events.Select(e => e.EventId)
+            .ShouldBe(["e5", "t4", "t3", "t2", "t1", "t0"]);
+        // Forward is unchanged: [At(1), At(3)) ascending.
+        (await src.ReadEventsAsync("s", At(1), At(3), 0, reverse: false, Ct)).Events.Select(e => e.EventId)
+            .ShouldBe(["e1", "t0", "t1", "t2", "t3", "t4"]);
+    }
+
+    [Fact]
+    public async Task A_capped_reverse_read_keeps_the_LATEST_events_and_flags_truncation()
+    {
+        using var src = await SeedAsync();
+        var r = await src.ReadEventsAsync("s", At(10), At(-1), 3, reverse: true, Ct);
+        r.Events.Select(e => e.EventId).ShouldBe(["e6", "e5", "t4"]);
+        r.ContinuationPoint.ShouldNotBeNull();
+        // An exact fit is complete.
+        (await src.ReadEventsAsync("s", At(10), At(-1), 9, reverse: true, Ct)).ContinuationPoint.ShouldBeNull();
+    }
+
+    [Fact]
+    public async Task Paging_a_reverse_read_through_a_tie_cluster_visits_every_event_once_newest_first()
+    {
+        using var src = await SeedAsync();
+        foreach (var cap in new[] { 1, 2, 3, 4 })
+        {
+            var all = new List<string>();
+            var lo = At(-1);
+            var from = At(10);
+            var skip = 0;
+            for (var page = 0; ; page++)
+            {
+                page.ShouldBeLessThan(40, "paging must terminate");
+                var r = await src.ReadEventsAsync("s", from, lo, cap + skip, reverse: true, Ct);
+                var events = r.Events.ToList();
+                var drop = 0;
+                while (drop < skip && drop < events.Count && events[drop].EventTimeUtc == from) drop++;
+                events = events.Skip(drop).ToList();
+                // The server asks for cap + skip rows (it re-reads the boundary ties it then drops), so a page is never
+                // emptied by the trim while more remains.
+                if (r.ContinuationPoint is not null) events.Count.ShouldBe(cap);
+
+                all.AddRange(events.Select(e => e.EventId));
+                if (r.ContinuationPoint is null) break;
+                var boundary = events[^1].EventTimeUtc;
+                var ties = events.AsEnumerable().Reverse().TakeWhile(e => e.EventTimeUtc == boundary).Count();
+                skip = boundary == from ? skip + ties : ties;
+                from = boundary;
+            }
+
+            all.SequenceEqual(NewestFirst).ShouldBeTrue($"cap {cap}: {string.Join(",", all)}");
+        }
+    }
+
+    [Fact]
+    public async Task Reverse_read_with_a_null_source_spans_every_source()
+    {
+        using var src = await SeedAsync();
+        var r = await src.ReadEventsAsync(null, At(2.5), At(1.5), 0, reverse: true, Ct);
+        r.Events.Select(e => e.EventId).ShouldBe(["t4", "t3", "t2", "t1", "t0", "o0"]);
+    }
+}

tests/Drivers/Historian.Conformance/IConformanceBackend.cs

@@ -41,6 +41,13 @@ public interface IConformanceBackend : IAsyncDisposable
     /// <param name="samples">The rows to store.</param>
     Task SeedAsync(string tag, params (DateTime T, HistorianValue V, uint Status)[] samples);
 
+    /// <summary>
+    ///     Writes historical events directly in the backend's event table (never through the alarm writer): event id,
+    ///     source and time as given (rounded to the storage resolution), severity 500, received time = event time.
+    /// </summary>
+    /// <param name="events">The events to store.</param>
+    Task SeedEventsAsync(params (DateTime T, string Id, string Source)[] events);
+
     /// <summary>
     ///     Live (non-deleted) rows for a tag, ascending by time, read directly from storage. The status is returned
     ///     VERBATIM as stored — there is no read-side clamp (an Empty row stored non-Bad reads back non-Bad here).

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.IntegrationTests/Series/WireBackendTests.cs

@@ -71,7 +71,7 @@ public sealed class WireBackendTests
             await driver.InitializeAsync("{}", ct);
 
             await WaitFor(() =>
-                driver.GetDeviceState(DeviceHost) is { FixedTreeCache: not null }, TimeSpan.FromSeconds(5));
+                driver.GetDeviceState(DeviceHost) is { FixedTreeCache: not null }, WaitTimeout);
 
             var state = driver.GetDeviceState(DeviceHost);
             state.ShouldNotBeNull();
@@ -82,7 +82,7 @@ public sealed class WireBackendTests
 
             await WaitFor(() =>
                 state.LastFixedSnapshots.ContainsKey($"{DeviceHost}/Axes/X/AbsolutePosition"),
-                TimeSpan.FromSeconds(3));
+                WaitTimeout);
             state.LastFixedSnapshots[$"{DeviceHost}/Axes/X/AbsolutePosition"].ShouldBe(123456);
         }
     }
@@ -136,7 +136,7 @@ public sealed class WireBackendTests
 
             await WaitFor(() =>
                 driver.GetDeviceState(DeviceHost) is { LastProgramInfo: not null },
-                TimeSpan.FromSeconds(5));
+                WaitTimeout);
 
             var snapshots = await driver.ReadAsync(
                 [$"{DeviceHost}/Program/Name",
@@ -194,7 +194,7 @@ public sealed class WireBackendTests
             {
                 var state = driver.GetDeviceState(DeviceHost);
                 return state is not null && state.LastTimers.Count == 4;
-            }, TimeSpan.FromSeconds(5));
+            }, WaitTimeout);
 
             var snapshots = await driver.ReadAsync(
                 [$"{DeviceHost}/Timers/PowerOnSeconds",
@@ -265,8 +265,11 @@ public sealed class WireBackendTests
             {
                 var state = driver.GetDeviceState(DeviceHost);
                 return state?.FixedTreeCache is { Capabilities.SpindleLoad: true, Capabilities.SpindleMotorSpeed: true }
-                    && state.LastSpindleLoads.Count >= 2;
-            }, TimeSpan.FromSeconds(5));
+                    && state.LastSpindleLoads.Count >= 2
+                    // Motor speeds are cached after a SECOND wire round-trip (FocasDriver spindle poll), so the loads
+                    // arriving first does not mean the speeds have — waiting on loads alone raced under load (#678.3).
+                    && state.LastSpindleMotorSpeeds.Count >= 2;
+            }, WaitTimeout);
 
             var snapshots = await driver.ReadAsync(
                 [$"{DeviceHost}/Spindle/S1/Load",
@@ -282,6 +285,10 @@ public sealed class WireBackendTests
         }
     }
 
+    /// <summary>Generous: the sim fixture answers fast, but a loaded CI host (e.g. a concurrent docker build) does not.</summary>
+    private static readonly TimeSpan WaitTimeout = TimeSpan.FromSeconds(15);
+
+    /// <summary>Polls <paramref name="pred"/>; FAILS the test with a clear message on timeout rather than returning silently.</summary>
     private static async Task WaitFor(Func<bool> pred, TimeSpan timeout)
     {
         var deadline = DateTime.UtcNow + timeout;
@@ -290,5 +297,7 @@ public sealed class WireBackendTests
             if (pred()) return;
             await Task.Delay(50);
         }
+        if (pred()) return;
+        Assert.Fail($"Condition not met within {timeout.TotalSeconds:0.#}s waiting on the FOCAS wire backend.");
     }
 }

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/GatewayEventBoundsTests.cs

@@ -0,0 +1,123 @@
+using System.Net;
+using Google.Protobuf.WellKnownTypes;
+using Grpc.Core;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Server.Kestrel.Core;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.HistorianGateway.Contracts.Grpc;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Runtime.Historian;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests;
+
+/// <summary>
+///     Gitea #675: the Gateway backend's event-read bounds and direction, offline.
+///     <list type="bullet">
+///       <item>A reverse (newest-first) read is refused before anything is sent — the gateway streams ascending only.</item>
+///       <item>The open upper bound a start-only forward read uses (<c>DateTime.MaxValue</c>, UTC kind) survives the
+///         PUBLISHED client package's proto conversion — captured on the wire by an in-process gRPC server — and the
+///         Windows FILETIME encoding the gateway converts it to. The live AVEVA leg (what the historian does with a
+///         year-9999 bound) stays open: it needs the VPN.</item>
+///     </list>
+/// </summary>
+public sealed class GatewayEventBoundsTests
+{
+    private static readonly DateTime UtcMax = new(DateTime.MaxValue.Ticks, DateTimeKind.Utc);
+    private static CancellationToken Ct => TestContext.Current.CancellationToken;
+
+    [Fact]
+    public async Task A_reverse_events_read_is_refused_and_sends_nothing()
+    {
+        var fake = new FakeHistorianGatewayClient();
+        IHistorianDataSource ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+
+        await Should.ThrowAsync<NotSupportedException>(() =>
+            ds.ReadEventsAsync("Pump1", DateTime.UtcNow, DateTime.UtcNow.AddHours(-1), 10, reverse: true, Ct));
+        fake.ReadEventsCallCount.ShouldBe(0);
+
+        // Forward through the same overload is the five-argument read, unchanged.
+        await ds.ReadEventsAsync("Pump1", DateTime.UtcNow.AddHours(-1), DateTime.UtcNow, 10, reverse: false, Ct);
+        fake.ReadEventsCallCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public void UtcMax_round_trips_through_the_proto_Timestamp_and_FILETIME_encodings()
+    {
+        var ts = Timestamp.FromDateTime(UtcMax);
+        ts.ToDateTime().ShouldBe(UtcMax);
+        ts.ToDateTime().Kind.ShouldBe(DateTimeKind.Utc);
+
+        // The gateway hands its bounds to the historian as FILETIME (100 ns since 1601) — in range up to year 30828.
+        var fileTime = ts.ToDateTime().ToFileTimeUtc();
+        DateTime.FromFileTimeUtc(fileTime).ShouldBe(UtcMax);
+    }
+
+    [Fact]
+    public async Task A_start_only_bound_of_UtcMax_reaches_the_wire_intact_through_the_published_client()
+    {
+        var capture = new CapturingReadService();
+        await using var server = await StartServerAsync(capture);
+        using var adapter = HistorianGatewayClientAdapter.Create(
+            new ServerHistorianOptions
+            {
+                Enabled = true,
+                Endpoint = $"http://127.0.0.1:{server.Port}",
+                ApiKey = "histgw_test_key",
+                UseTls = false,
+            },
+            NullLoggerFactory.Instance);
+        IHistorianDataSource ds = new GatewayHistorianDataSource(adapter, NullLogger<GatewayHistorianDataSource>.Instance);
+
+        var start = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var r = await ds.ReadEventsAsync("Pump1", start, UtcMax, 5, Ct);
+
+        r.Events.ShouldBeEmpty();
+        capture.Request.ShouldNotBeNull();
+        capture.Request!.StartTime.ToDateTime().ShouldBe(start);
+        capture.Request.EndTime.ToDateTime().ShouldBe(UtcMax);
+        DateTime.FromFileTimeUtc(capture.Request.EndTime.ToDateTime().ToFileTimeUtc()).ShouldBe(UtcMax);
+    }
+
+    private sealed class CapturingReadService : HistorianRead.HistorianReadBase
+    {
+        public ReadEventsRequest? Request { get; private set; }
+
+        public override Task ReadEvents(
+            ReadEventsRequest request, IServerStreamWriter<HistorianEvent> responseStream, ServerCallContext context)
+        {
+            Request = request;
+            return Task.CompletedTask;
+        }
+    }
+
+    private sealed class Server(WebApplication app, int port) : IAsyncDisposable
+    {
+        public int Port { get; } = port;
+
+        public async ValueTask DisposeAsync()
+        {
+            await app.StopAsync();
+            await app.DisposeAsync();
+        }
+    }
+
+    private static async Task<Server> StartServerAsync(CapturingReadService service)
+    {
+        var builder = WebApplication.CreateSlimBuilder();
+        builder.Logging.ClearProviders();
+        builder.WebHost.ConfigureKestrel(k =>
+            k.Listen(IPAddress.Loopback, 0, o => o.Protocols = HttpProtocols.Http2));
+        builder.Services.AddGrpc();
+        builder.Services.AddSingleton(service);
+        var app = builder.Build();
+        app.MapGrpcService<CapturingReadService>();
+        await app.StartAsync();
+        var port = new Uri(app.Urls.First()).Port;
+        return new Server(app, port);
+    }
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests.csproj

@@ -15,12 +15,18 @@
         <PackageReference Include="Microsoft.NET.Test.Sdk"/>
         <!-- ServiceCollection + BuildServiceProvider for the CreateDataSource factory test. -->
         <PackageReference Include="Microsoft.Extensions.DependencyInjection"/>
+        <!-- In-process gRPC server capturing the published client's ReadEvents request (#675 bounds pin). -->
+        <PackageReference Include="Grpc.AspNetCore"/>
         <PackageReference Include="xunit.runner.visualstudio">
             <PrivateAssets>all</PrivateAssets>
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
         </PackageReference>
     </ItemGroup>
 
+    <ItemGroup>
+        <FrameworkReference Include="Microsoft.AspNetCore.App"/>
+    </ItemGroup>
+
     <ItemGroup>
         <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway\ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.csproj"/>
     </ItemGroup>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests/QuestDbConformance.cs

@@ -60,3 +60,10 @@ public sealed class QuestDbModifiedValueConformance(QuestDbFixture fx) : Modifie
     /// <inheritdoc/>
     protected override Task<IConformanceBackend> CreateBackendAsync() => QuestDbConformanceBackend.CreateAsync(fx);
 }
+
+[Collection(QuestDbCollection.Name)]
+public sealed class QuestDbEventReadConformance(QuestDbFixture fx) : EventReadConformance
+{
+    /// <inheritdoc/>
+    protected override Task<IConformanceBackend> CreateBackendAsync() => QuestDbConformanceBackend.CreateAsync(fx);
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests/QuestDbConformanceBackend.cs

@@ -143,6 +143,27 @@ internal sealed class QuestDbConformanceBackend : IConformanceBackend
         await Wal.WaitAsync(Conn.SampleTable, CancellationToken.None);
     }
 
+    /// <inheritdoc/>
+    public async Task SeedEventsAsync(params (DateTime T, string Id, string Source)[] events)
+    {
+        await using (var c = await Conn.OpenAsync(CancellationToken.None))
+        {
+            foreach (var (t, id, source) in events)
+            {
+                await using var cmd = Conn.CreateCommand(c,
+                    $"INSERT INTO {Conn.EventTable} (ts, event_id, source, severity, message, received_utc) VALUES ($1, $2, $3, $4, $5, $6)");
+                QuestDbConnection.BindTimestamp(cmd, t);
+                QuestDbConnection.BindText(cmd, id);
+                QuestDbConnection.BindText(cmd, source);
+                cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Integer, Value = 500 });
+                QuestDbConnection.BindText(cmd, null);
+                QuestDbConnection.BindTimestamp(cmd, t);
+                await cmd.ExecuteNonQueryAsync();
+            }
+        }
+        await Wal.WaitAsync(Conn.EventTable, CancellationToken.None);
+    }
+
     /// <summary>Runs a statement against this table set (test-only escape hatch for hand-made rows), then waits for WAL visibility of the sample table.</summary>
     /// <param name="sql">The statement; parameters are bound positionally by <paramref name="bind"/>.</param>
     /// <param name="bind">Binds the parameters.</param>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests/TtlWallClockTests.cs

@@ -0,0 +1,80 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests;
+
+/// <summary>
+///     Gitea #674.1 — pins the QuestDB TTL behaviour the historian's retention relies on: a table TTL is judged against
+///     the wall clock (<c>min(max timestamp, now)</c>), so one far-future row — a 2066 typo that reached the backend
+///     without going through the node manager's <c>HistoryUpdateMaxFutureSkew</c> bound — cannot age out every older
+///     partition, including the Part 11 modification trail (the record of who changed history).
+/// </summary>
+/// <remarks>
+///     <para>
+///         <b>Positive control.</b> A partition genuinely older than the TTL (40 days, against a 30-day TTL) is kept until
+///         the far-future commit and evicted BY it — proving TTL housekeeping ran on exactly the commit that could have
+///         dropped the in-TTL partitions. Without it the "nothing evicted" assertion would also pass against a table
+///         whose TTL never ran.
+///     </para>
+///     <para>
+///         ⚠️ Observed on QuestDB 10.0.1 (2026-10-11): the in-TTL partitions also survived with
+///         <c>cairo.ttl.use.wall.clock=false</c> (verified effective via <c>SHOW PARAMETERS</c>), so this test does not
+///         isolate that flag — it pins the outcome. Keep the flag at its default (<c>true</c>) regardless; the server-side
+///         future-skew bound is the primary guard.
+///     </para>
+/// </remarks>
+[Collection(QuestDbCollection.Name)]
+public sealed class TtlWallClockTests(QuestDbFixture fx)
+{
+    private static CancellationToken Ct => TestContext.Current.CancellationToken;
+    private static readonly HistoryUpdateContext Who = new("ttl-test", null);
+
+    [Fact]
+    public async Task A_far_future_row_evicts_only_partitions_older_than_the_ttl_by_the_wall_clock()
+    {
+        fx.SkipIfUnavailable();
+        var o = fx.Options(fx.UniquePrefix(), retentionDays: 30);
+        var c = new QuestDbConnection(o);
+        var wal = new QuestDbWalVisibility(c, o.VisibilityTimeout);
+        var tags = new QuestDbTagCatalog(c, new QuestDbSchemaBootstrapper(c, o), wal);
+        var updater = new QuestDbHistorianDataUpdater(c, tags, wal);
+
+        // Whole seconds (µs-aligned), one row per DAY partition. With the newest row 10 days old, the 40-day partition is
+        // still inside the TTL measured from the table's max timestamp, so this commit evicts nothing.
+        var now = DateTime.UtcNow;
+        var today = new DateTime(now.Year, now.Month, now.Day, now.Hour, now.Minute, now.Second, DateTimeKind.Utc);
+        DateTime[] older = [today.AddDays(-40), today.AddDays(-20), today.AddDays(-10)];
+        (await updater.UpdateDataAsync("ttl.tag", HistoryUpdateMode.Insert, older.Select((t, i) => V(t, i)).ToList(), Who, Ct))
+            .ShouldAllBe(code => code == HistorianStatusCodes.GoodEntryInserted);
+        (await DaysAsync(c, c.SampleTable)).ShouldBe(older.Select(t => t.Date));
+        (await DaysAsync(c, c.SampleModifiedTable)).ShouldBe(older.Select(t => t.Date));
+
+        // The far-future row, then one more ordinary commit (TTL housekeeping runs on commits).
+        (await updater.UpdateDataAsync("ttl.tag", HistoryUpdateMode.Insert,
+            [V(new DateTime(2066, 1, 1, 0, 0, 0, DateTimeKind.Utc), 9)], Who, Ct)).ShouldBe([HistorianStatusCodes.GoodEntryInserted]);
+        (await updater.UpdateDataAsync("ttl.tag", HistoryUpdateMode.Insert, [V(today, 10)], Who, Ct))
+            .ShouldBe([HistorianStatusCodes.GoodEntryInserted]);
+        (await wal.WaitAsync(c.SampleTable, Ct)).ShouldBeTrue();
+        (await wal.WaitAsync(c.SampleModifiedTable, Ct)).ShouldBeTrue();
+
+        // Only the genuinely expired 40-day partition is gone; the 20- and 10-day partitions survive in both tables.
+        DateTime[] expected = [today.AddDays(-20).Date, today.AddDays(-10).Date, today.Date, new(2066, 1, 1)];
+        (await DaysAsync(c, c.SampleTable)).ShouldBe(expected);
+        (await DaysAsync(c, c.SampleModifiedTable)).ShouldBe(expected);
+    }
+
+    private static HistorizationValue V(DateTime t, double v) => new(t, HistorianValue.FromDouble(v), HistorianStatusCodes.Good);
+
+    /// <summary>The distinct UTC days holding rows, ascending.</summary>
+    private static async Task<List<DateTime>> DaysAsync(QuestDbConnection c, string table)
+    {
+        await using var conn = await c.OpenAsync(Ct);
+        await using var cmd = c.CreateCommand(conn, $"SELECT ts FROM {table} ORDER BY ts");
+        await using var r = await cmd.ExecuteReaderAsync(Ct);
+        var days = new SortedSet<DateTime>();
+        while (await r.ReadAsync(Ct)) days.Add(QuestDbConnection.ReadUtc(r, 0).Date);
+        return days.ToList();
+    }
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/StatusCodeOracleTests.cs

@@ -14,6 +14,11 @@ public sealed class StatusCodeOracleTests
         ((uint)Opc.Ua.AggregateBits.Calculated).ShouldBe(HistorianInfoBits.HistorianCalculated);
     }
 
+    /// <summary>#674: the v1-schema refusal code is the SDK's BadHistoryOperationUnsupported.</summary>
+    [Fact]
+    public void History_operation_unsupported_matches_the_SDK() =>
+        HistorianStatusCodes.BadHistoryOperationUnsupported.ShouldBe(Opc.Ua.StatusCodes.BadHistoryOperationUnsupported);
+
     [Fact]
     public void Interpolated_bits_match_the_SDK()
     {

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/ModifiedHistoryAtomicityTests.cs

@@ -54,7 +54,7 @@ public sealed class ModifiedHistoryAtomicityTests(SqlHistorianFixture fx)
     public async Task A_replace_whose_trail_insert_fails_changes_nothing()
     {
         var db = await ReadTestDb.CreateAsync(fx);
-        var u = new SqlServerHistorianDataUpdater(db.Conn, new SqlServerTagCatalog(db.Conn, db.Boot));
+        var u = new SqlServerHistorianDataUpdater(db.Conn, db.Boot, new SqlServerTagCatalog(db.Conn, db.Boot));
         (await u.UpdateDataAsync("t", HistoryUpdateMode.Insert, [V(T1, 1)], Who, CancellationToken.None))
             .ShouldBe([HistorianStatusCodes.GoodEntryInserted]);
         (await CountTrailAsync(db)).ShouldBe(1);
@@ -78,7 +78,7 @@ public sealed class ModifiedHistoryAtomicityTests(SqlHistorianFixture fx)
     public async Task Deletes_whose_trail_insert_fails_delete_nothing()
     {
         var db = await ReadTestDb.CreateAsync(fx);
-        var u = new SqlServerHistorianDataUpdater(db.Conn, new SqlServerTagCatalog(db.Conn, db.Boot));
+        var u = new SqlServerHistorianDataUpdater(db.Conn, db.Boot, new SqlServerTagCatalog(db.Conn, db.Boot));
         await u.UpdateDataAsync("t", HistoryUpdateMode.Insert, [V(T1, 1), V(T2, 2)], Who, CancellationToken.None);
 
         await BreakTheTrailAsync(db);
@@ -99,7 +99,7 @@ public sealed class ModifiedHistoryAtomicityTests(SqlHistorianFixture fx)
     public async Task An_over_long_principal_is_truncated_never_refused()
     {
         var db = await ReadTestDb.CreateAsync(fx);
-        var u = new SqlServerHistorianDataUpdater(db.Conn, new SqlServerTagCatalog(db.Conn, db.Boot));
+        var u = new SqlServerHistorianDataUpdater(db.Conn, db.Boot, new SqlServerTagCatalog(db.Conn, db.Boot));
         var who = new HistoryUpdateContext(new string('p', 500), new string('k', 500));
 
         (await u.UpdateDataAsync("t", HistoryUpdateMode.Insert, [V(T1, 1)], who, CancellationToken.None))

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/RetentionTests.cs

@@ -178,6 +178,97 @@ public sealed class RetentionTests(SqlHistorianFixture fx)
         (await LockIsFreeAsync(s)).ShouldBeTrue();
     }
 
+    [Fact]
+    public async Task Cancelling_mid_command_while_the_delete_is_blocked_still_releases_the_applock()
+    {
+        fx.SkipIfUnavailable();
+        var (c, b, _, s) = Make();
+        await SeedAsync(b, s);
+
+        // A second session holds an exclusive table lock, so the purger's first DELETE blocks server-side.
+        await using var holder = new SqlConnection(fx.ConnectionString);
+        await holder.OpenAsync();
+        await using var tx = (SqlTransaction)await holder.BeginTransactionAsync();
+        await using (var cmd = holder.CreateCommand())
+        {
+            cmd.Transaction = tx;
+            cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Sample WITH (TABLOCKX, HOLDLOCK)";
+            await cmd.ExecuteScalarAsync();
+        }
+        short holderSpid;
+        await using (var cmd = holder.CreateCommand())
+        {
+            cmd.Transaction = tx;
+            cmd.CommandText = "SELECT CAST(@@SPID AS smallint)";
+            holderSpid = (short)(await cmd.ExecuteScalarAsync())!;
+        }
+
+        using var cts = new CancellationTokenSource();
+        var purger = new SqlServerHistorianRetention(c, b, TimeSpan.FromHours(1), 30, 4000, time: new FixedTime(Now));
+        var purge = purger.PurgeAsync(cts.Token);
+
+        // Cancel only once the server reports a DELETE actually blocked behind the holder — a fixed delay could
+        // cancel during bootstrap/applock acquisition on a slow host and never exercise the mid-command path.
+        var deadline = DateTime.UtcNow.AddSeconds(15);
+        while (await CountAsync(
+                   $"SELECT COUNT(*) FROM sys.dm_exec_requests WHERE blocking_session_id = {holderSpid} AND command = 'DELETE'") == 0)
+        {
+            purge.IsCompleted.ShouldBeFalse("the purge finished without ever blocking on the holder's table lock");
+            DateTime.UtcNow.ShouldBeLessThan(deadline, "the purge's DELETE never blocked behind the holder");
+            await Task.Delay(50);
+        }
+        cts.Cancel();
+
+        // SqlClient surfaces the attention as OperationCanceledException or as a SqlException.
+        var ex = await Should.ThrowAsync<Exception>(() => purge);
+        (ex is OperationCanceledException or SqlException).ShouldBeTrue($"unexpected {ex.GetType().Name}: {ex.Message}");
+
+        await tx.RollbackAsync();
+        (await LockIsFreeAsync(s)).ShouldBeTrue();
+        (await CountAsync($"SELECT COUNT(*) FROM [{s}].Sample")).ShouldBe(21);
+    }
+
+    [Fact]
+    public async Task A_failing_release_falls_back_to_clearing_the_pool_so_the_applock_is_freed()
+    {
+        fx.SkipIfUnavailable();
+        var (c, b, _, s) = Make();
+        await SeedAsync(b, s);
+        var purger = new SqlServerHistorianRetention(c, b, TimeSpan.FromHours(1), 30, 4000, time: new FixedTime(Now))
+        {
+            ReleaseSql = "EXEC sp_this_procedure_does_not_exist;",
+        };
+
+        await purger.PurgeAsync(CancellationToken.None);
+
+        (await LockIsFreeAsync(s)).ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task Falsification_control_a_failing_release_with_a_no_op_ClearPool_leaves_the_applock_held()
+    {
+        fx.SkipIfUnavailable();
+        var (c, b, _, s) = Make();
+        await SeedAsync(b, s);
+        var purger = new SqlServerHistorianRetention(c, b, TimeSpan.FromHours(1), 30, 4000, time: new FixedTime(Now))
+        {
+            ReleaseSql = "EXEC sp_this_procedure_does_not_exist;",
+            ClearPool = _ => { },
+        };
+
+        await purger.PurgeAsync(CancellationToken.None);
+
+        try
+        {
+            // The pooled session still owns the Session-scoped lock: proves the fallback test above is not vacuous.
+            (await LockIsFreeAsync(s)).ShouldBeFalse();
+        }
+        finally
+        {
+            SqlConnection.ClearAllPools(); // drop the leaked session so the lock does not outlive the test
+        }
+    }
+
     [Fact]
     public async Task A_throwing_purge_releases_the_applock()
     {

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/SchemaBootstrapIntegrationTests.cs

@@ -32,7 +32,7 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
         var s = SqlHistorianFixture.UniqueSchema();
         await Boot(Opts(s)).EnsureAsync(CancellationToken.None);
         await Boot(Opts(s)).EnsureAsync(CancellationToken.None); // fresh instance => re-runs the guarded path
-        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.RequiredVersion);
+        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.ModifiedTrailVersion);
         (await ScalarAsync($"SELECT COUNT(*) FROM sys.indexes WHERE name='CX_Event_Time' AND object_id=OBJECT_ID('[{s}].Event')")).ShouldBe(1);
     }
 
@@ -51,13 +51,14 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
             cmd.CommandText = b;
             await cmd.ExecuteNonQueryAsync();
         }
-        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.RequiredVersion);
+        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.ModifiedTrailVersion);
     }
 
     /// <summary>
     ///     #668 upgrade path: a schema left at version 1 (only <c>001_initial.sql</c> applied, as every pre-#668 install is)
     ///     is upgraded in place by an auto-creating bootstrap — <c>SampleModified</c> appears, both version rows exist, and
-    ///     existing samples are untouched. With <c>AutoCreateSchema=false</c> the same v1 schema is refused.
+    ///     existing samples are untouched. With <c>AutoCreateSchema=false</c> the same v1 schema is accepted with the
+    ///     modification trail switched off and left at v1 (#674).
     /// </summary>
     [Fact]
     public async Task A_version_1_schema_is_upgraded_to_version_2_in_place()
@@ -81,11 +82,15 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
         }
         (await ScalarAsync($"SELECT COUNT(*) FROM sys.tables WHERE name = 'SampleModified' AND schema_id = SCHEMA_ID('{s}')")).ShouldBe(0);
 
-        var refused = await Should.ThrowAsync<HistorianSchemaMissingException>(
-            () => Boot(Opts(s, auto: false)).EnsureAsync(CancellationToken.None));
-        refused.Message.ShouldContain("missing version 2 (found 1)");
+        // #674: verify-only accepts v1 — with the modification trail switched off — and does not upgrade it.
+        var verifyOnly = Boot(Opts(s, auto: false));
+        await verifyOnly.EnsureAsync(CancellationToken.None);
+        verifyOnly.SupportsModifiedTrail.ShouldBeFalse();
+        (await ScalarAsync($"SELECT MAX(Version) FROM [{s}].SchemaVersion")).ShouldBe(1);
 
-        await Boot(Opts(s)).EnsureAsync(CancellationToken.None);
+        var upgrading = Boot(Opts(s));
+        await upgrading.EnsureAsync(CancellationToken.None);
+        upgrading.SupportsModifiedTrail.ShouldBeTrue();
 
         (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(2);
         (await ScalarAsync($"SELECT MAX(Version) FROM [{s}].SchemaVersion")).ShouldBe(2);
@@ -101,7 +106,7 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
         var s = SqlHistorianFixture.UniqueSchema();
         var tasks = Enumerable.Range(0, 4).Select(_ => Task.Run(() => Boot(Opts(s)).EnsureAsync(CancellationToken.None))).ToArray();
         await Task.WhenAll(tasks);
-        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.RequiredVersion);
+        (await ScalarAsync($"SELECT COUNT(*) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.ModifiedTrailVersion);
     }
 
     [Fact]
@@ -110,7 +115,7 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
         fx.SkipIfUnavailable();
         var ex = await Should.ThrowAsync<HistorianSchemaMissingException>(
             () => Boot(Opts(SqlHistorianFixture.UniqueSchema(), auto: false)).EnsureAsync(CancellationToken.None));
-        ex.Message.ShouldContain("missing version 2");
+        ex.Message.ShouldContain("missing version 1 (found 0)");
     }
 
     [Fact]

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/SchemaV1PostureTests.cs

@@ -0,0 +1,181 @@
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Logging;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+/// <summary>
+///     Gitea #674: a database left at schema version 1 (no Part 11 <c>SampleModified</c> trail) with
+///     <c>AutoCreateSchema=false</c> keeps historizing. Before #674 the bootstrapper required v2 and refused EVERY call —
+///     live writes, raw reads, alarm events, retention — until script 002 was applied by hand. Now only the features
+///     that need the trail are refused (<c>BadHistoryOperationUnsupported</c>, nothing sent to SQL), and the
+///     bootstrapper logs ONE warning for the whole provider. Built through <see cref="SqlServerHistorianProvider"/>, the
+///     production wiring, so every seam shares the one bootstrapper the way a node does.
+/// </summary>
+[Collection(SqlHistorianCollection.Name)]
+public sealed class SchemaV1PostureTests(SqlHistorianFixture fx)
+{
+    private static CancellationToken Ct => TestContext.Current.CancellationToken;
+    private static readonly DateTime Recent = DateTime.UtcNow.AddHours(-1);
+    private static readonly HistoryUpdateContext Who = new("editor", "k1");
+
+    [Fact]
+    public async Task A_v1_schema_keeps_historizing_and_refuses_only_the_modified_trail_features()
+    {
+        fx.SkipIfUnavailable();
+        var s = SqlHistorianFixture.UniqueSchema();
+        await ApplyV1Async(s);
+        var old = DateTime.UtcNow.AddDays(-40);
+        var loggers = new CapturingLoggerFactory();
+        var provider = new SqlServerHistorianProvider(new SqlServerHistorianOptions
+        {
+            ConnectionString = fx.ConnectionString, Schema = s, AutoCreateSchema = false, RetentionDays = 30,
+        });
+        var sp = new LoggerServices(loggers);
+
+        // Live writes (the continuous-historization drain) and raw reads work.
+        var writer = provider.CreateValueWriter(sp);
+        (await writer.WriteLiveValuesAsync("Plant.Speed",
+            [new HistorizationValue(old, HistorianValue.FromDouble(1), 0), new HistorizationValue(Recent, HistorianValue.FromDouble(2), 0)],
+            Ct)).ShouldBeTrue();
+        var source = provider.CreateDataSource(sp);
+        var raw = await source.ReadRawAsync("Plant.Speed", Recent.AddMinutes(-1), Recent.AddMinutes(1), 10, Ct);
+        raw.Samples.Select(v => v.Value).ShouldBe([2d]);
+
+        // Alarm events are written.
+        var alarms = provider.CreateAlarmWriter(sp);
+        (await alarms.WriteBatchAsync(
+            [new AlarmHistorianEvent("alarm-1", "Plant/Line/Eq", "HiTemp", "LimitAlarm", AlarmSeverity.High, "Activated", "m", "u", null, Recent)],
+            Ct)).ShouldBe([HistorianWriteOutcome.Ack]);
+        (await CountAsync($"SELECT COUNT(*) FROM [{s}].Event")).ShouldBe(1);
+
+        // Modified reads: the interface's "no trail" signal (the node manager reports BadHistoryOperationUnsupported),
+        // not a backend failure — health stays clean.
+        await Should.ThrowAsync<NotSupportedException>(() =>
+            source.ReadModifiedAsync("Plant.Speed", Recent.AddDays(-1), Recent.AddDays(1), 10, null, Ct));
+        source.GetHealthSnapshot().LastError.ShouldBeNull();
+
+        // HistoryUpdate: every item refused, and NOTHING reaches SQL — a sent MERGE/DELETE would either change the
+        // samples or fail on the missing SampleModified target; an Insert on an unknown tag would create its Tag row.
+        var updater = provider.CreateUpdater(sp)!;
+        var tagsBefore = await CountAsync($"SELECT COUNT(*) FROM [{s}].Tag");
+        (await updater.UpdateDataAsync("Plant.Speed", HistoryUpdateMode.Update,
+            [new HistorizationValue(Recent, HistorianValue.FromDouble(99), 0), new HistorizationValue(Recent.AddSeconds(1), HistorianValue.FromDouble(98), 0)],
+            Who, Ct)).ShouldBe([HistorianStatusCodes.BadHistoryOperationUnsupported, HistorianStatusCodes.BadHistoryOperationUnsupported]);
+        (await updater.UpdateDataAsync("Plant.Brand.New", HistoryUpdateMode.Insert,
+            [new HistorizationValue(Recent, HistorianValue.FromDouble(1), 0)], Who, Ct))
+            .ShouldBe([HistorianStatusCodes.BadHistoryOperationUnsupported]);
+        (await updater.DeleteRawAsync("Plant.Speed", Recent.AddMinutes(-1), Recent.AddMinutes(1), Who, Ct))
+            .ShouldBe(HistorianStatusCodes.BadHistoryOperationUnsupported);
+        (await updater.DeleteAtTimeAsync("Plant.Speed", [Recent], Who, Ct))
+            .ShouldBe([HistorianStatusCodes.BadHistoryOperationUnsupported]);
+        (await CountAsync($"SELECT COUNT(*) FROM [{s}].Tag")).ShouldBe(tagsBefore);
+        (await source.ReadRawAsync("Plant.Speed", Recent.AddMinutes(-1), Recent.AddMinutes(1), 10, Ct))
+            .Samples.Select(v => v.Value).ShouldBe([2d]);
+
+        // Retention purges samples and skips the trail it does not have.
+        var purge = await provider.CreateRetention(sp)!.PurgeAsync(Ct);
+        purge.Select(r => r.Table).ShouldBe(["Sample", "Event"]);
+        purge.Single(r => r.Table == "Sample").Rows.ShouldBe(1);
+        (await CountAsync($"SELECT COUNT(*) FROM [{s}].Sample")).ShouldBe(1);
+
+        // One warning for the whole provider (= per boot), however many seams and calls touched the bootstrapper.
+        loggers.Warnings.Count(w => w.Contains("Part 11 modification trail is unavailable")).ShouldBe(1);
+        (await CountAsync($"SELECT MAX(Version) FROM [{s}].SchemaVersion")).ShouldBe(1); // verify-only: never upgraded
+    }
+
+    /// <summary>
+    ///     #674: <c>AutoCreateSchema=true</c> still upgrades a v1 schema to v2 — the modification trail appears and a
+    ///     HistoryUpdate is recorded in it — and logs no v1 warning.
+    /// </summary>
+    [Fact]
+    public async Task Auto_create_still_upgrades_a_v1_schema_and_enables_the_trail()
+    {
+        fx.SkipIfUnavailable();
+        var s = SqlHistorianFixture.UniqueSchema();
+        await ApplyV1Async(s);
+        var loggers = new CapturingLoggerFactory();
+        var provider = new SqlServerHistorianProvider(new SqlServerHistorianOptions
+        {
+            ConnectionString = fx.ConnectionString, Schema = s, AutoCreateSchema = true,
+        });
+        var sp = new LoggerServices(loggers);
+
+        (await provider.CreateUpdater(sp)!.UpdateDataAsync("Plant.Speed", HistoryUpdateMode.Insert,
+            [new HistorizationValue(Recent, HistorianValue.FromDouble(5), 0)], Who, Ct))
+            .ShouldBe([HistorianStatusCodes.GoodEntryInserted]);
+
+        (await CountAsync($"SELECT MAX(Version) FROM [{s}].SchemaVersion")).ShouldBe(SqlServerSchemaBootstrapper.ModifiedTrailVersion);
+        var trail = await provider.CreateDataSource(sp)
+            .ReadModifiedAsync("Plant.Speed", Recent.AddMinutes(-1), Recent.AddMinutes(1), 10, null, Ct);
+        trail.Values.ShouldHaveSingleItem().UpdateType.ShouldBe(HistoryModificationType.Insert);
+        loggers.Warnings.ShouldNotContain(w => w.Contains("Part 11 modification trail is unavailable"));
+    }
+
+    private async Task ApplyV1Async(string schema)
+    {
+        var v1 = new StreamReader(typeof(SqlServerSchemaBootstrapper).Assembly.GetManifestResourceStream("Schema.001_initial.sql")!).ReadToEnd();
+        await using var c = new SqlConnection(fx.ConnectionString);
+        await c.OpenAsync(Ct);
+        foreach (var b in SqlServerSchemaBootstrapper.SplitBatches(v1.Replace("$(Schema)", schema)))
+        {
+            await using var cmd = c.CreateCommand();
+            cmd.CommandText = b;
+            await cmd.ExecuteNonQueryAsync(Ct);
+        }
+    }
+
+    private async Task<long> CountAsync(string sql)
+    {
+        await using var c = new SqlConnection(fx.ConnectionString);
+        await c.OpenAsync(Ct);
+        await using var cmd = c.CreateCommand();
+        cmd.CommandText = sql;
+        return Convert.ToInt64(await cmd.ExecuteScalarAsync(Ct));
+    }
+
+    /// <summary>The only service the provider resolves is <see cref="ILoggerFactory"/>.</summary>
+    private sealed class LoggerServices(ILoggerFactory loggers) : IServiceProvider
+    {
+        public object? GetService(Type serviceType) => serviceType == typeof(ILoggerFactory) ? loggers : null;
+    }
+
+    /// <summary>Captures every Warning-or-above message from every logger it creates.</summary>
+    private sealed class CapturingLoggerFactory : ILoggerFactory
+    {
+        private readonly List<string> _warnings = [];
+
+        public IReadOnlyList<string> Warnings
+        {
+            get { lock (_warnings) return _warnings.ToList(); }
+        }
+
+        public ILogger CreateLogger(string categoryName) => new Capturing(this);
+
+        public void AddProvider(ILoggerProvider provider)
+        {
+        }
+
+        public void Dispose()
+        {
+        }
+
+        private sealed class Capturing(CapturingLoggerFactory owner) : ILogger
+        {
+            public IDisposable? BeginScope<TState>(TState state) where TState : notnull => null;
+
+            public bool IsEnabled(LogLevel logLevel) => true;
+
+            public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception,
+                Func<TState, Exception?, string> formatter)
+            {
+                if (logLevel < LogLevel.Warning) return;
+                lock (owner._warnings) owner._warnings.Add(formatter(state, exception));
+            }
+        }
+    }
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/SqlServerConformance.cs

@@ -60,3 +60,10 @@ public sealed class SqlServerModifiedValueConformance(SqlHistorianFixture fx) :
     /// <inheritdoc/>
     protected override Task<IConformanceBackend> CreateBackendAsync() => SqlServerConformanceBackend.CreateAsync(fx);
 }
+
+[Collection(SqlHistorianCollection.Name)]
+public sealed class SqlServerEventReadConformance(SqlHistorianFixture fx) : EventReadConformance
+{
+    /// <inheritdoc/>
+    protected override Task<IConformanceBackend> CreateBackendAsync() => SqlServerConformanceBackend.CreateAsync(fx);
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/SqlServerConformanceBackend.cs

@@ -34,12 +34,28 @@ internal sealed class SqlServerConformanceBackend : IConformanceBackend
 
     /// <inheritdoc/>
     public IHistorianDataUpdater CreateUpdater() =>
-        new SqlServerHistorianDataUpdater(_db.Conn, new SqlServerTagCatalog(_db.Conn, _db.Boot));
+        new SqlServerHistorianDataUpdater(_db.Conn, _db.Boot, new SqlServerTagCatalog(_db.Conn, _db.Boot));
 
     /// <inheritdoc/>
     public async Task SeedAsync(string tag, params (DateTime T, HistorianValue V, uint Status)[] samples) =>
         await _db.SeedAsync(tag, samples);
 
+    /// <inheritdoc/>
+    public async Task SeedEventsAsync(params (DateTime T, string Id, string Source)[] events)
+    {
+        await using var c = await _db.Conn.OpenAsync(CancellationToken.None);
+        foreach (var (t, id, source) in events)
+        {
+            await using var cmd = _db.Conn.CreateCommand(c,
+                $"INSERT {_db.Conn.Q("Event")} (EventId, SourceName, AlarmId, AlarmName, AlarmTypeName, Severity, EventKind, Message, " +
+                "UserName, Comment, EventTimeUtc, ReceivedTimeUtc) VALUES (@id, @src, 'a', 'n', 'T', 500, 'Activated', NULL, NULL, NULL, @t, @t)");
+            cmd.Parameters.AddWithValue("@id", id);
+            cmd.Parameters.AddWithValue("@src", source);
+            SqlHistorianConnection.AddDateTime2(cmd, "@t", t);
+            await cmd.ExecuteNonQueryAsync();
+        }
+    }
+
     /// <inheritdoc/>
     public async Task<IReadOnlyList<(DateTime T, HistorianValue V, uint Status)>> ReadBackAsync(string tag)
     {

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/SchemaScriptTests.cs

@@ -32,7 +32,7 @@ public sealed class SchemaScriptTests
 
     /// <summary>
     ///     #668: schema v2 (the Part 11 modification trail) is embedded, matches its docs copy, records version 2 (which
-    ///     must equal <see cref="SqlServerSchemaBootstrapper.RequiredVersion"/>), and carries none of the constructs an
+    ///     must equal <see cref="SqlServerSchemaBootstrapper.ModifiedTrailVersion"/>), and carries none of the constructs an
     ///     <c>OUTPUT … INTO</c> target forbids (FOREIGN KEY / CHECK / trigger) — any of them would fail every HistoryUpdate.
     /// </summary>
     [Fact]
@@ -45,7 +45,8 @@ public sealed class SchemaScriptTests
         text.ShouldContain("[SampleModified]");
         text.ShouldContain("PRIMARY KEY CLUSTERED (TagId, SourceTimeUtc, ModifiedId)");
         text.ShouldContain("VALUES (2, SYSUTCDATETIME())");
-        SqlServerSchemaBootstrapper.RequiredVersion.ShouldBe(2);
+        SqlServerSchemaBootstrapper.ModifiedTrailVersion.ShouldBe(2);
+        SqlServerSchemaBootstrapper.RequiredVersion.ShouldBe(1); // #674: v1 is still served, without the trail
         var ddl = string.Join('\n', text.Split('\n').Where(l => !l.TrimStart().StartsWith("--", StringComparison.Ordinal)));
         ddl.ShouldNotContain("FOREIGN KEY", Case.Insensitive);
         ddl.ShouldNotContain("CHECK", Case.Insensitive);