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 46bbe08a..d952ba71 100644
--- a/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json
+++ b/archreview/plans/R2-11-tagconfig-consolidation-plan.md.tasks.json
@@ -2,7 +2,7 @@
   "planPath": "archreview/plans/R2-11-tagconfig-consolidation-plan.md",
   "lastUpdated": "2026-07-12",
   "tasks": [
-    { "id": "T1",  "subject": "Golden TagConfig corpus + compose→encode→decode parity characterization test (Runtime.Tests, green on unmodified tree)", "status": "pending", "blockedBy": [] },
+    { "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": "pending", "blockedBy": [] },
     { "id": "T3",  "subject": "TagConfigIntent + TagAlarmIntent in Commons/Types (TDD; port composer semantics verbatim + OpcUaServer ExtractTag* test tables)", "status": "pending", "blockedBy": [] },
     { "id": "T4",  "subject": "DeviceConfigIntent (TryExtractHost/NormalizeHost) in Commons/Types (TDD)", "status": "pending", "blockedBy": [] },
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigCorpusParityTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigCorpusParityTests.cs
new file mode 100644
index 00000000..562c27a4
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigCorpusParityTests.cs
@@ -0,0 +1,111 @@
+using System.Linq;
+using System.Text.Json;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
+using ZB.MOM.WW.OtOpcUa.OpcUaServer;
+using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
+
+namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;
+
+/// <summary>
+///     The cross-seam characterization net for R2-11 (01/C-1 + 01/P-1). Composes one equipment tag per
+///     <see cref="TagConfigGoldenCorpus"/> blob, serialises the SAME draft to the artifact blob shape,
+///     decodes it, and asserts the decoded <see cref="EquipmentTagPlan"/> list equals the composer's
+///     element-wise (positional-record value equality) over the WHOLE corpus. Because both producers parse
+///     the identical raw <c>TagConfig</c> string, this proves the four byte-parity parse sites agree TODAY,
+///     and is the permanent regression guard held green through every subsequent seam swap
+///     (<c>TagConfigIntent.Parse</c> consolidation).
+/// </summary>
+public sealed class TagConfigCorpusParityTests
+{
+    [Fact]
+    public void Composer_and_artifact_agree_over_the_whole_TagConfig_corpus()
+    {
+        var ns = new Namespace
+        {
+            NamespaceId = "ns-eq",
+            ClusterId = "c1",
+            Kind = NamespaceKind.Equipment,
+            NamespaceUri = "urn:eq",
+        };
+        var driver = new DriverInstance
+        {
+            DriverInstanceId = "drv-1",
+            ClusterId = "c1",
+            NamespaceId = "ns-eq",
+            Name = "Modbus1",
+            DriverType = "Modbus",
+            DriverConfig = "{}",
+        };
+        var area = new UnsArea { UnsAreaId = "area-1", ClusterId = "c1", Name = "filling" };
+        var line = new UnsLine { UnsLineId = "line-1", UnsAreaId = "area-1", Name = "line-1" };
+        var equip = new Equipment
+        {
+            EquipmentId = "eq-1",
+            DriverInstanceId = "drv-1",
+            UnsLineId = "line-1",
+            Name = "Machine_001",
+            MachineCode = "MACHINE_001",
+        };
+
+        var tags = TagConfigGoldenCorpus.Blobs
+            .Select((blob, i) => new Tag
+            {
+                TagId = $"tag-{i:D2}",
+                DriverInstanceId = "drv-1",
+                EquipmentId = "eq-1",
+                FolderPath = null,
+                Name = $"Sig{i:D2}",
+                DataType = "Float",
+                AccessLevel = TagAccessLevel.Read,
+                TagConfig = blob,
+            })
+            .ToArray();
+
+        // ---- Side 1: the live-edit composer ----
+        var composed = AddressSpaceComposer.Compose(
+            new[] { area }, new[] { line }, new[] { equip },
+            new[] { driver }, Array.Empty<ScriptedAlarm>(), tags, new[] { ns });
+
+        // ---- Side 2: serialise the SAME draft to the artifact blob shape, then decode it ----
+        var blob = JsonSerializer.SerializeToUtf8Bytes(new
+        {
+            Namespaces = new[]
+            {
+                new { ns.NamespaceId, ns.ClusterId, Kind = (int)ns.Kind },
+            },
+            DriverInstances = new[]
+            {
+                new { driver.DriverInstanceId, driver.DriverType, driver.DriverConfig, driver.NamespaceId, driver.ClusterId },
+            },
+            Tags = tags.Select(ToSnapshot).ToArray(),
+        });
+
+        var decoded = DeploymentArtifact.ParseComposition(blob);
+
+        decoded.EquipmentTags.Count.ShouldBe(tags.Length);
+        // Full byte-parity: every field, same order (positional-record value equality). A field-by-field
+        // spell-out per blob so a divergence names the offending corpus entry.
+        for (var i = 0; i < composed.EquipmentTags.Count; i++)
+        {
+            var c = composed.EquipmentTags[i];
+            var d = decoded.EquipmentTags.Single(t => t.TagId == c.TagId);
+            d.ShouldBe(c, customMessage: $"corpus blob #{c.TagId} diverged: '{tags.Single(t => t.TagId == c.TagId).TagConfig}'");
+        }
+        decoded.EquipmentTags.SequenceEqual(composed.EquipmentTags).ShouldBeTrue();
+    }
+
+    private static object ToSnapshot(Tag t) => new
+    {
+        t.TagId,
+        t.DriverInstanceId,
+        t.EquipmentId,
+        t.Name,
+        t.FolderPath,
+        t.DataType,
+        AccessLevel = (int)t.AccessLevel,
+        t.TagConfig,
+    };
+}
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigGoldenCorpus.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigGoldenCorpus.cs
new file mode 100644
index 00000000..a76bed77
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/TagConfigGoldenCorpus.cs
@@ -0,0 +1,83 @@
+namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;
+
+/// <summary>
+///     The shared golden corpus of <c>TagConfig</c> JSON blobs used to characterise the cross-driver
+///     platform-intent parse (FullName / alarm / isHistorized / historianTagname / isArray / arrayLength).
+///     Every entry is a NON-NULL string (the DB <c>CK_Tag_TagConfig_IsJson</c> constraint guarantees a
+///     non-null TagConfig for a real deploy) so the compose→encode→decode parity test
+///     (<see cref="TagConfigCorpusParityTests"/>) can round-trip each through both equipment-tag producers
+///     and assert byte-parity field-by-field. The <c>null</c>-input divergence (composer returns the raw
+///     null, artifact coalesces to "") is a documented seam handled only at the
+///     <c>TagConfigIntent.Parse</c> unit level, not through the parity round-trip.
+///     <para>Covers: happy path, blank, non-object root, malformed JSON, FullName absent/non-string/whitespace,
+///     alarm object with each field absent/wrong-type, historizeToAveva true/false/non-bool,
+///     historianTagname whitespace, isArray/arrayLength combinations (incl. negative/overflow/non-number/
+///     length-without-flag/zero), unknown keys, and mixed platform+driver keys.</para>
+/// </summary>
+public static class TagConfigGoldenCorpus
+{
+    /// <summary>The corpus blobs, index-ordered. The parity test builds one equipment tag per blob.</summary>
+    public static readonly IReadOnlyList<string> Blobs = new[]
+    {
+        // 0 happy path
+        "{\"FullName\":\"X.Y\"}",
+        // 1 blank (whitespace) — FullName falls back to the raw (blank) blob on both seams
+        "   ",
+        // 2 non-object root
+        "[1,2]",
+        // 3 malformed JSON
+        "not json {",
+        // 4 FullName absent (driver keys only) — FullName = raw blob
+        "{\"region\":\"HoldingRegisters\",\"address\":5}",
+        // 5 FullName present but non-string — FullName = raw blob
+        "{\"FullName\":123}",
+        // 6 FullName whitespace value (not trimmed)
+        "{\"FullName\":\"   \"}",
+        // 7 alarm empty object → defaults (AlarmCondition, 500, historize null)
+        "{\"FullName\":\"A\",\"alarm\":{}}",
+        // 8 alarm fully specified
+        "{\"FullName\":\"A\",\"alarm\":{\"alarmType\":\"OffNormalAlarm\",\"severity\":700}}",
+        // 9 alarm non-object → no alarm
+        "{\"FullName\":\"A\",\"alarm\":\"oops\"}",
+        // 10 alarm historizeToAveva true
+        "{\"FullName\":\"A\",\"alarm\":{\"alarmType\":\"LimitAlarm\",\"severity\":500,\"historizeToAveva\":true}}",
+        // 11 alarm historizeToAveva false
+        "{\"FullName\":\"A\",\"alarm\":{\"alarmType\":\"LimitAlarm\",\"severity\":500,\"historizeToAveva\":false}}",
+        // 12 alarm historizeToAveva non-bool → null
+        "{\"FullName\":\"A\",\"alarm\":{\"alarmType\":\"LimitAlarm\",\"severity\":500,\"historizeToAveva\":\"oops\"}}",
+        // 13 alarm severity non-number → 500
+        "{\"FullName\":\"A\",\"alarm\":{\"severity\":\"high\"}}",
+        // 14 alarm alarmType non-string → AlarmCondition
+        "{\"FullName\":\"A\",\"alarm\":{\"alarmType\":123}}",
+        // 15 isHistorized true
+        "{\"FullName\":\"A\",\"isHistorized\":true}",
+        // 16 isHistorized true + explicit tagname
+        "{\"FullName\":\"A\",\"isHistorized\":true,\"historianTagname\":\"P.L.X\"}",
+        // 17 isHistorized false + JSON-null tagname
+        "{\"FullName\":\"A\",\"isHistorized\":false,\"historianTagname\":null}",
+        // 18 historianTagname whitespace → null
+        "{\"FullName\":\"A\",\"isHistorized\":true,\"historianTagname\":\"   \"}",
+        // 19 isHistorized non-bool → false
+        "{\"FullName\":\"A\",\"isHistorized\":\"yes\"}",
+        // 20 isArray true + length
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":16}",
+        // 21 isArray true, no length
+        "{\"FullName\":\"A\",\"isArray\":true}",
+        // 22 isArray false + length → scalar
+        "{\"FullName\":\"A\",\"isArray\":false,\"arrayLength\":16}",
+        // 23 isArray true, length 0 → true, 0
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":0}",
+        // 24 arrayLength non-number → true, null
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":\"16\"}",
+        // 25 arrayLength negative → true, null
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":-1}",
+        // 26 arrayLength float → true, null
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":16.5}",
+        // 27 arrayLength overflow (uint.MaxValue + 1) → true, null
+        "{\"FullName\":\"A\",\"isArray\":true,\"arrayLength\":4294967296}",
+        // 28 unknown + mixed platform/driver keys
+        "{\"FullName\":\"A.B\",\"region\":\"Coils\",\"address\":5,\"dataType\":\"Int16\",\"isHistorized\":true,\"alarm\":{\"severity\":250},\"foo\":\"bar\"}",
+        // 29 all intents combined
+        "{\"FullName\":\"C.D\",\"isArray\":true,\"arrayLength\":4,\"isHistorized\":true,\"historianTagname\":\"H\",\"alarm\":{\"alarmType\":\"DiscreteAlarm\",\"severity\":900,\"historizeToAveva\":false}}",
+    };
+}