diff --git a/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json b/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json
index 6bbe0462..42326c7b 100644
--- a/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json
+++ b/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json
@@ -5,7 +5,7 @@
     { "id": "T1",  "subject": "Golden TagConfig corpus + compose→encode→decode parity characterization test (Runtime.Tests, green on unmodified tree)", "status": "completed", "blockedBy": [] },
     { "id": "T2",  "subject": "FullName-semantics characterization for EquipmentNodeWalker (Core.Tests) + DraftValidator Galaxy rule (Configuration.Tests)", "status": "completed", "blockedBy": [] },
     { "id": "T3",  "subject": "TagConfigIntent + TagAlarmIntent in Commons/Types (TDD; port composer semantics verbatim + OpcUaServer ExtractTag* test tables)", "status": "completed", "blockedBy": [] },
-    { "id": "T4",  "subject": "DeviceConfigIntent (TryExtractHost/NormalizeHost) in Commons/Types (TDD)", "status": "pending", "blockedBy": [] },
+    { "id": "T4",  "subject": "DeviceConfigIntent (TryExtractHost/NormalizeHost) in Commons/Types (TDD)", "status": "completed", "blockedBy": [] },
     { "id": "T5",  "subject": "AddressSpaceComposer swap: single TagConfigIntent.Parse per tag, delete 4 Extract* statics (P-1 parse-once)", "status": "pending", "blockedBy": ["T1", "T3"] },
     { "id": "T6",  "subject": "Device-host re-home: composer TryExtractDeviceHost/NormalizeDeviceHost → DeviceConfigIntent; update DriverHostActor + DeploymentArtifact callers", "status": "pending", "blockedBy": ["T4", "T5"] },
     { "id": "T7",  "subject": "DeploymentArtifact swap: delete 4 private mirrors, parse once per tag element via TagConfigIntent", "status": "pending", "blockedBy": ["T5"] },
diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Commons/Types/DeviceConfigIntent.cs b/src/Core/ZB.MOM.WW.OtOpcUa.Commons/Types/DeviceConfigIntent.cs
new file mode 100644
index 00000000..cca42273
--- /dev/null
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Commons/Types/DeviceConfigIntent.cs
@@ -0,0 +1,47 @@
+using System.Text.Json;
+
+namespace ZB.MOM.WW.OtOpcUa.Commons.Types;
+
+/// <summary>
+///     SINGLE SOURCE OF TRUTH for extracting + normalizing a <c>Device</c>'s connection host from its
+///     schemaless <c>DeviceConfig</c> JSON. Shared by the live-compose seam (<c>AddressSpaceComposer</c>),
+///     the artifact-decode seam (<c>DeploymentArtifact</c>), and the FixedTree-partition path
+///     (<c>DriverHostActor</c>) so an <c>EquipmentNode.DeviceHost</c> and a driver-discovered device-host
+///     folder segment for the same device compare byte-equal. Ported verbatim from the historical
+///     <c>AddressSpaceComposer.TryExtractDeviceHost</c> / <c>NormalizeDeviceHost</c>.
+/// </summary>
+public static class DeviceConfigIntent
+{
+    /// <summary>
+    ///     Extract a <c>Device</c>'s connection host from its schemaless <c>DeviceConfig</c> JSON: the
+    ///     top-level <c>"HostAddress"</c> string (e.g. <c>"10.201.31.5:8193"</c>). Returns
+    ///     <see langword="null"/> when the config is blank, not a JSON object, has no string
+    ///     <c>HostAddress</c>, or the value is blank/whitespace. Never throws. The returned host is
+    ///     deterministically normalized via <see cref="NormalizeHost"/> (trim + lower-case).
+    /// </summary>
+    /// <param name="deviceConfigJson">The device's schemaless <c>DeviceConfig</c> JSON blob.</param>
+    /// <returns>The normalized device host, or <see langword="null"/> when absent/blank/unparseable.</returns>
+    public static string? TryExtractHost(string? deviceConfigJson)
+    {
+        if (string.IsNullOrWhiteSpace(deviceConfigJson)) return null;
+        try
+        {
+            using var doc = JsonDocument.Parse(deviceConfigJson);
+            if (doc.RootElement.ValueKind != JsonValueKind.Object) return null;
+            if (!doc.RootElement.TryGetProperty("HostAddress", out var hostEl)
+                || hostEl.ValueKind != JsonValueKind.String) return null;
+            var raw = hostEl.GetString();
+            if (string.IsNullOrWhiteSpace(raw)) return null;
+            return NormalizeHost(raw);
+        }
+        catch (JsonException) { return null; }
+    }
+
+    /// <summary>
+    ///     The single normalization authority for a device host: trims surrounding whitespace and
+    ///     lower-cases (invariant). Idempotent (an already-normalized value is unchanged).
+    /// </summary>
+    /// <param name="host">The raw host string (non-null; a non-empty <c>HostAddress</c> or folder segment).</param>
+    /// <returns>The normalized host (trimmed + lower-cased).</returns>
+    public static string NormalizeHost(string host) => host.Trim().ToLowerInvariant();
+}
diff --git a/tests/Core/ZB.MOM.WW.OtOpcUa.Commons.Tests/DeviceConfigIntentTests.cs b/tests/Core/ZB.MOM.WW.OtOpcUa.Commons.Tests/DeviceConfigIntentTests.cs
new file mode 100644
index 00000000..55e6db11
--- /dev/null
+++ b/tests/Core/ZB.MOM.WW.OtOpcUa.Commons.Tests/DeviceConfigIntentTests.cs
@@ -0,0 +1,46 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Commons.Types;
+
+namespace ZB.MOM.WW.OtOpcUa.Commons.Tests;
+
+/// <summary>
+///     Pins <see cref="DeviceConfigIntent"/> device-host extraction + normalization semantics (ported
+///     from the historical composer statics; R2-11): null on blank/non-object/non-string/whitespace,
+///     trim+lower normalization, and idempotence.
+/// </summary>
+public sealed class DeviceConfigIntentTests
+{
+    [Theory]
+    [InlineData("{\"HostAddress\":\"10.0.0.5:8193\"}", "10.0.0.5:8193")]
+    [InlineData("{\"HostAddress\":\"  HOST:8193  \"}", "host:8193")]       // trim + lower
+    [InlineData("{\"HostAddress\":\"HOST:8193\",\"other\":1}", "host:8193")]
+    // null-yielding cases
+    [InlineData(null, null)]
+    [InlineData("", null)]
+    [InlineData("   ", null)]
+    [InlineData("not json {", null)]
+    [InlineData("[1,2]", null)]                                            // non-object root
+    [InlineData("{\"HostAddress\":123}", null)]                           // non-string
+    [InlineData("{\"HostAddress\":\"   \"}", null)]                       // whitespace value
+    [InlineData("{\"other\":\"x\"}", null)]                              // absent
+    public void TryExtractHost(string? cfg, string? expected)
+    {
+        DeviceConfigIntent.TryExtractHost(cfg).ShouldBe(expected);
+    }
+
+    [Theory]
+    [InlineData("  HOST:8193  ", "host:8193")]
+    [InlineData("host:8193", "host:8193")]
+    public void NormalizeHost_trims_and_lowercases(string raw, string expected)
+    {
+        DeviceConfigIntent.NormalizeHost(raw).ShouldBe(expected);
+    }
+
+    [Fact]
+    public void NormalizeHost_is_idempotent()
+    {
+        var once = DeviceConfigIntent.NormalizeHost("  HOST:8193 ");
+        DeviceConfigIntent.NormalizeHost(once).ShouldBe(once);
+    }
+}