diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway/Mapping/HistorianTypeMapper.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway/Mapping/HistorianTypeMapper.cs
new file mode 100644
index 00000000..97631961
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway/Mapping/HistorianTypeMapper.cs
@@ -0,0 +1,63 @@
+using ZB.MOM.WW.HistorianGateway.Contracts.Grpc;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Mapping;
+
+/// <summary>
+/// Maps the driver-agnostic <see cref="DriverDataType"/> onto the gateway's
+/// <see cref="HistorianDataType"/> for tag provisioning + historical writes.
+/// </summary>
+/// <remarks>
+/// Only the nine numeric types are historizable on the gateway's analog write path. Two of them
+/// fall back to a wider historian type because the narrower one's write path is deferred upstream:
+/// <see cref="DriverDataType.UInt16"/> maps to <see cref="HistorianDataType.Uint4"/> (the historian's
+/// <c>UInt2</c> write path is not proven). String / DateTime / Reference are not historized in v1
+/// and throw <see cref="NotSupportedException"/>; callers that want to skip them without catching an
+/// exception should consult <see cref="IsHistorizable(DriverDataType)"/> first.
+/// </remarks>
+internal static class HistorianTypeMapper
+{
+    /// <summary>Maps a driver data type to the historian data type used for provisioning/writes.</summary>
+    /// <param name="dataType">The driver-agnostic data type.</param>
+    /// <returns>The matching <see cref="HistorianDataType"/>.</returns>
+    /// <exception cref="NotSupportedException">
+    /// The type is explicitly deferred (string/datetime/reference) or a future, unclassified member.
+    /// </exception>
+    public static HistorianDataType ToHistorianDataType(DriverDataType dataType) => dataType switch
+    {
+        DriverDataType.Boolean => HistorianDataType.Int1,
+        DriverDataType.Int16 => HistorianDataType.Int2,
+        DriverDataType.Int32 => HistorianDataType.Int4,
+        DriverDataType.Int64 => HistorianDataType.Int8,
+        DriverDataType.UInt16 => HistorianDataType.Uint4, // UInt2 write path deferred upstream → widen
+        DriverDataType.UInt32 => HistorianDataType.Uint4,
+        DriverDataType.UInt64 => HistorianDataType.Uint8,
+        DriverDataType.Float32 => HistorianDataType.Float,
+        DriverDataType.Float64 => HistorianDataType.Double,
+        DriverDataType.String or DriverDataType.DateTime or DriverDataType.Reference =>
+            throw new NotSupportedException(
+                $"DriverDataType.{dataType} is not historized in v1 " +
+                "(string/datetime/reference writes are deferred — gated on the analog SQL write path)."),
+        _ => throw new NotSupportedException(
+            $"DriverDataType.{dataType} is not classified for historian write mapping — add a HistorianDataType mapping."),
+    };
+
+    /// <summary>
+    /// True when <paramref name="dataType"/> is one of the nine historizable numeric types — lets the
+    /// provisioning hook skip deferred types without catching <see cref="NotSupportedException"/>.
+    /// </summary>
+    /// <param name="dataType">The driver-agnostic data type.</param>
+    public static bool IsHistorizable(DriverDataType dataType) => dataType switch
+    {
+        DriverDataType.Boolean
+            or DriverDataType.Int16
+            or DriverDataType.Int32
+            or DriverDataType.Int64
+            or DriverDataType.UInt16
+            or DriverDataType.UInt32
+            or DriverDataType.UInt64
+            or DriverDataType.Float32
+            or DriverDataType.Float64 => true,
+        _ => false,
+    };
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Mapping/HistorianTypeMapperTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Mapping/HistorianTypeMapperTests.cs
new file mode 100644
index 00000000..1dde2678
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Mapping/HistorianTypeMapperTests.cs
@@ -0,0 +1,52 @@
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;        // DriverDataType
+using ZB.MOM.WW.HistorianGateway.Contracts.Grpc;  // HistorianDataType
+using ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Mapping;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests.Mapping;
+
+public sealed class HistorianTypeMapperTests
+{
+    [Theory]
+    [InlineData(DriverDataType.Boolean, HistorianDataType.Int1)]
+    [InlineData(DriverDataType.Int16,   HistorianDataType.Int2)]
+    [InlineData(DriverDataType.Int32,   HistorianDataType.Int4)]
+    [InlineData(DriverDataType.Int64,   HistorianDataType.Int8)]
+    [InlineData(DriverDataType.UInt16,  HistorianDataType.Uint4)]  // fallback: UInt2 write deferred upstream
+    [InlineData(DriverDataType.UInt32,  HistorianDataType.Uint4)]
+    [InlineData(DriverDataType.UInt64,  HistorianDataType.Uint8)]
+    [InlineData(DriverDataType.Float32, HistorianDataType.Float)]
+    [InlineData(DriverDataType.Float64, HistorianDataType.Double)]
+    public void Maps_writable_numeric_types(DriverDataType d, HistorianDataType expected)
+        => Assert.Equal(expected, HistorianTypeMapper.ToHistorianDataType(d));
+
+    [Theory]
+    [InlineData(DriverDataType.String)]
+    [InlineData(DriverDataType.DateTime)]
+    [InlineData(DriverDataType.Reference)]
+    public void Deferred_types_throw_NotSupported_with_clear_message(DriverDataType d)
+    {
+        var ex = Assert.Throws<NotSupportedException>(() => HistorianTypeMapper.ToHistorianDataType(d));
+        Assert.Contains("not historized in v1", ex.Message);  // human-actionable, no tag value leaked
+    }
+
+    [Fact] // matrix guard: a new DriverDataType member must be classified (mapped or explicitly deferred)
+    public void Every_DriverDataType_member_is_classified()
+    {
+        foreach (var d in Enum.GetValues<DriverDataType>())
+        {
+            try { _ = HistorianTypeMapper.ToHistorianDataType(d); }
+            catch (NotSupportedException) { /* explicitly deferred — acceptable */ }
+            // any OTHER exception (e.g. ArgumentOutOfRangeException from an unhandled new member) fails the test
+        }
+    }
+
+    [Theory]
+    [InlineData(DriverDataType.Boolean, true)]
+    [InlineData(DriverDataType.Float64, true)]
+    [InlineData(DriverDataType.String,  false)]
+    [InlineData(DriverDataType.DateTime, false)]
+    [InlineData(DriverDataType.Reference, false)]
+    public void IsHistorizable_matches_writable_set(DriverDataType d, bool expected)
+        => Assert.Equal(expected, HistorianTypeMapper.IsHistorizable(d));
+}