diff --git a/src/AVEVA.Historian.Client/HistorianSession.cs b/src/AVEVA.Historian.Client/HistorianSession.cs
new file mode 100644
index 0000000..9873fa2
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+++ b/src/AVEVA.Historian.Client/HistorianSession.cs
@@ -0,0 +1,186 @@
+using System.Runtime.CompilerServices;
+using AVEVA.Historian.Client.Grpc;
+using AVEVA.Historian.Client.Models;
+
+namespace AVEVA.Historian.Client;
+
+/// <summary>A live, reusable authenticated Historian session: holds one gRPC connection + one
+/// OpenConnection handle and runs ops on them WITHOUT re-handshaking. Reuse across ops amortizes the
+/// auth handshake. Idle-expires server-side in ~20-25s — callers keep it warm (PingAsync) or re-open.
+/// Reads/historical-write/tag-write/status only; events are NOT exposed (separate channel+auth).</summary>
+public sealed class HistorianSession : IAsyncDisposable
+{
+    private readonly HistorianGrpcConnection _connection;
+    private readonly HistorianGrpcHandshake.Session _session;
+    private readonly HistorianClientOptions _options;
+
+    /// <summary>Whether this session was opened read-only or write-enabled (the Open2 connection mode).</summary>
+    public HistorianSessionKind Kind { get; }
+
+    internal HistorianSession(
+        HistorianGrpcConnection connection,
+        HistorianGrpcHandshake.Session session,
+        HistorianClientOptions options,
+        HistorianSessionKind kind)
+    {
+        _connection = connection;
+        _session = session;
+        _options = options;
+        Kind = kind;
+    }
+
+    // --- reads (mirror the orchestrators' async-enumerable wrapping; call the …OnSession seams,
+    //     which take the transient uint client handle) ---
+
+    /// <summary>Raw values for <paramref name="tag"/> in [<paramref name="startUtc"/>,
+    /// <paramref name="endUtc"/>], capped at <paramref name="maxValues"/>, on the held session.</summary>
+    public async IAsyncEnumerable<HistorianSample> ReadRawAsync(
+        string tag,
+        DateTime startUtc,
+        DateTime endUtc,
+        int maxValues,
+        [EnumeratorCancellation] CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcReadOrchestrator(_options);
+        IReadOnlyList<HistorianSample> rows = await Task.Run(
+            () => orch.RunRawQueryOnSession(_connection, _session.ClientHandle, tag, startUtc, endUtc, maxValues, ct), ct)
+            .ConfigureAwait(false);
+        foreach (HistorianSample sample in rows)
+        {
+            ct.ThrowIfCancellationRequested();
+            yield return sample;
+        }
+    }
+
+    /// <summary>Aggregate values for <paramref name="tag"/> over [<paramref name="startUtc"/>,
+    /// <paramref name="endUtc"/>] in <paramref name="interval"/> buckets, using the supplied
+    /// retrieval <paramref name="mode"/>, on the held session.</summary>
+    public async IAsyncEnumerable<HistorianAggregateSample> ReadAggregateAsync(
+        string tag,
+        DateTime startUtc,
+        DateTime endUtc,
+        RetrievalMode mode,
+        TimeSpan interval,
+        [EnumeratorCancellation] CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcReadOrchestrator(_options);
+        IReadOnlyList<HistorianAggregateSample> rows = await Task.Run(
+            () => orch.RunAggregateQueryOnSession(_connection, _session.ClientHandle, tag, startUtc, endUtc, mode, interval, ct), ct)
+            .ConfigureAwait(false);
+        foreach (HistorianAggregateSample sample in rows)
+        {
+            ct.ThrowIfCancellationRequested();
+            yield return sample;
+        }
+    }
+
+    /// <summary>Interpolated values for <paramref name="tag"/> at each of the supplied
+    /// <paramref name="timestampsUtc"/>, on the held session.</summary>
+    public Task<IReadOnlyList<HistorianSample>> ReadAtTimeAsync(
+        string tag,
+        IReadOnlyList<DateTime> timestampsUtc,
+        CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcReadOrchestrator(_options);
+        return Task.Run<IReadOnlyList<HistorianSample>>(
+            () => orch.RunAtTimeOnSession(_connection, _session.ClientHandle, tag, timestampsUtc, ct), ct);
+    }
+
+    // --- writes (the …OnSession seams take the full Session, since the historical write keys on the
+    //     string handle + tag GUID and the tag-config ops mix string/uint handles) ---
+
+    /// <summary>Writes historical/backfill values for <paramref name="tag"/> on the held (write-enabled) session.</summary>
+    public Task<bool> AddHistoricalValuesAsync(
+        string tag,
+        IReadOnlyList<HistorianHistoricalValue> values,
+        CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcHistoricalWriteOrchestrator(_options);
+        return Task.Run(() => orch.RunWriteOnSession(_connection, _session, tag, values, ct), ct);
+    }
+
+    /// <summary>Ensures the tag described by <paramref name="definition"/> exists on the held (write-enabled) session.</summary>
+    public Task<bool> EnsureTagAsync(HistorianTagDefinition definition, CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcTagWriteOrchestrator(_options);
+        return Task.Run(() => orch.EnsureTagOnSession(_connection, _session, definition, ct), ct);
+    }
+
+    /// <summary>Deletes <paramref name="tagName"/> on the held (write-enabled) session.</summary>
+    public Task<bool> DeleteTagAsync(string tagName, CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcTagWriteOrchestrator(_options);
+        return Task.Run(() => orch.DeleteTagOnSession(_connection, _session, tagName, ct), ct);
+    }
+
+    /// <summary>Renames the supplied (old,new) tag-name <paramref name="pairs"/> on the held (write-enabled) session.</summary>
+    public Task<HistorianTagRenameResult> RenameTagsAsync(
+        IReadOnlyList<(string OldName, string NewName)> pairs,
+        CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcTagWriteOrchestrator(_options);
+        return Task.Run(() => orch.RenameTagsOnSession(_connection, _session, pairs, ct), ct);
+    }
+
+    /// <summary>Adds extended <paramref name="properties"/> to <paramref name="tagName"/> on the held (write-enabled) session.</summary>
+    public Task<bool> AddTagExtendedPropertiesAsync(
+        string tagName,
+        IReadOnlyList<HistorianTagExtendedProperty> properties,
+        CancellationToken ct = default)
+    {
+        var orch = new HistorianGrpcTagWriteOrchestrator(_options);
+        return Task.Run(() => orch.AddTagExtendedPropertiesOnSession(_connection, _session, tagName, properties, ct), ct);
+    }
+
+    // --- status + keepalive (the status seams are static; handle shape differs per op) ---
+
+    /// <summary>Reads the named system parameter (e.g. "HistorianVersion") on the held session.</summary>
+    public Task<string?> GetSystemParameterAsync(string parameterName, CancellationToken ct = default)
+        => Task.Run(() => HistorianGrpcStatusClient.GetSystemParameterOnSession(
+            _connection, _session.ClientHandle, _options, parameterName, ct), ct);
+
+    /// <summary>Reports connection status derived from the held session's storage handle (no follow-on RPC).</summary>
+    public Task<HistorianConnectionStatus> GetConnectionStatusAsync(CancellationToken ct = default)
+        => Task.Run(() =>
+        {
+            (bool connected, string? error) = HistorianGrpcStatusClient.EvaluateConnectionStatusOnSession(_connection, _session);
+            return new HistorianConnectionStatus(
+                ServerName: _options.Host,
+                Pending: false,
+                ErrorOccurred: !connected,
+                Error: error,
+                ConnectedToServer: connected,
+                ConnectedToServerStorage: connected,
+                ConnectedToStoreForward: false,
+                ConnectionKind: HistorianConnectionKind.Process);
+        }, ct);
+
+    /// <summary>Reports a measured store-forward status (GetHistorianConsoleStatus) on the held session.</summary>
+    public Task<HistorianStoreForwardStatus> GetStoreForwardStatusAsync(CancellationToken ct = default)
+        => Task.Run(() =>
+        {
+            HistorianStoreForwardStatus NotStoring(bool errorOccurred, string? error) => new(
+                ServerName: _options.Host,
+                Pending: false,
+                ErrorOccurred: errorOccurred,
+                Error: error,
+                DataStored: false,
+                Storing: false,
+                ConnectionKind: HistorianConnectionKind.Process);
+
+            return HistorianGrpcStatusClient.GetStoreForwardStatusOnSession(
+                _connection, _session.StringHandle, _options, NotStoring, ct);
+        }, ct);
+
+    /// <summary>Keeps the session warm against the server's ~20-25s idle expiry by issuing a cheap
+    /// system-parameter read. Call periodically (or before a latency-sensitive op) to avoid re-handshaking.</summary>
+    public Task PingAsync(CancellationToken ct = default) => GetSystemParameterAsync("HistorianVersion", ct);
+
+    /// <summary>Disposes the underlying gRPC connection (closes the channel). The server-side session
+    /// also idle-expires on its own; this releases the local channel resources immediately.</summary>
+    public ValueTask DisposeAsync()
+    {
+        _connection.Dispose();
+        return ValueTask.CompletedTask;
+    }
+}