diff --git a/src/AR.Iec61850/Discovery/CdcInferenceEngine.cs b/src/AR.Iec61850/Discovery/CdcInferenceEngine.cs
index f580a835..f84e3b05 100644
--- a/src/AR.Iec61850/Discovery/CdcInferenceEngine.cs
+++ b/src/AR.Iec61850/Discovery/CdcInferenceEngine.cs
@@ -25,6 +25,62 @@ public static class CdcInferenceEngine
     public static bool IsKnownCdc(string cdc)
         => !string.IsNullOrWhiteSpace(cdc) && KnownCdcValues.Contains(cdc.Trim());
 
+    /// <summary>
+    /// Refines only low/medium-confidence generic status inference when the MMS
+    /// TypeSpecification provides an exact primitive stVal type. Exact wire type is
+    /// stronger evidence than the generic ST/stVal/q/t shape; object names are never
+    /// used as a substitute for missing type evidence.
+    /// </summary>
+    public static CdcInferenceResult RefineWithExactPrimaryType(
+        CdcInferenceResult inferred,
+        IReadOnlyCollection<LiveIedDataAttributeModel> attributes)
+    {
+        ArgumentNullException.ThrowIfNull(inferred);
+        ArgumentNullException.ThrowIfNull(attributes);
+
+        if (!string.Equals(inferred.Cdc, "SPS", StringComparison.OrdinalIgnoreCase) ||
+            inferred.Confidence >= 0.85)
+        {
+            return inferred;
+        }
+
+        var exactStatusValues = attributes
+            .Where(attribute =>
+                attribute.TypeConfidence == LiveIedDiscoveryConfidenceLevel.Exact &&
+                string.Equals(
+                    (attribute.AttributePath ?? string.Empty).Trim().Split('.').LastOrDefault(),
+                    "stVal",
+                    StringComparison.OrdinalIgnoreCase))
+            .ToArray();
+
+        if (exactStatusValues.Length != 1)
+            return inferred;
+
+        var primary = exactStatusValues[0];
+        var bType = (primary.SclBType ?? string.Empty).Trim().ToUpperInvariant();
+        var mmsType = (primary.MmsType ?? string.Empty).Trim().ToUpperInvariant();
+
+        if (IsExactSignedIntegerType(bType, mmsType))
+        {
+            return Result(
+                "INS",
+                0.96,
+                inferred.Evidence.Append(
+                    $"exact MMS TypeSpecification stVal={FirstNonEmpty(primary.SclBType, primary.MmsType)} overrides generic SPS shape"));
+        }
+
+        if (IsExactBooleanType(bType, mmsType))
+        {
+            return Result(
+                "SPS",
+                Math.Max(inferred.Confidence, 0.96),
+                inferred.Evidence.Append(
+                    $"exact MMS TypeSpecification stVal={FirstNonEmpty(primary.SclBType, primary.MmsType)} confirms SPS"));
+        }
+
+        return inferred;
+    }
+
     public static CdcInferenceResult Infer(
         string logicalNodeClass,
         string dataObjectName,
@@ -133,6 +189,18 @@ public static CdcInferenceResult Infer(
         return Result(string.Empty, 0.0, evidence.Append("CDC cannot be inferred from current online discovery only"));
     }
 
+    private static bool IsExactSignedIntegerType(string bType, string mmsType)
+        => bType is "INT8" or "INT16" or "INT24" or "INT32" or "INT64" or "INTEGER" ||
+           mmsType.Contains("INTEGER", StringComparison.Ordinal) ||
+           mmsType.Contains("SIGNED", StringComparison.Ordinal);
+
+    private static bool IsExactBooleanType(string bType, string mmsType)
+        => bType == "BOOLEAN" ||
+           mmsType.Contains("BOOLEAN", StringComparison.Ordinal);
+
+    private static string FirstNonEmpty(params string?[] values)
+        => values.FirstOrDefault(value => !string.IsNullOrWhiteSpace(value))?.Trim() ?? string.Empty;
+
     private static bool IsProtectionOperation(string lnClass, string dataObjectName)
         => string.Equals(dataObjectName, "Op", StringComparison.OrdinalIgnoreCase) &&
            ((lnClass.Length > 0 && lnClass[0] == 'P') || string.Equals(lnClass, "RREC", StringComparison.OrdinalIgnoreCase));
diff --git a/src/AR.Iec61850/Discovery/Iec61850StandardModelRegistry.cs b/src/AR.Iec61850/Discovery/Iec61850StandardModelRegistry.cs
index 904cd251..4e92e272 100644
--- a/src/AR.Iec61850/Discovery/Iec61850StandardModelRegistry.cs
+++ b/src/AR.Iec61850/Discovery/Iec61850StandardModelRegistry.cs
@@ -51,13 +51,13 @@ public static class Iec61850StandardModelRegistry
         [Key("MMXU", "PF")] = Def("MMXU", "PF", "WYE", 0.84, "power factor"),
 
         // Harmonic measurements use phase-group CDCs. Physical AA1E1F06R4
-        // plus IEDScout SCL prove that MHAI ThdA / ThdPhV are WYE objects whose
+        // plus field-reference SCL evidence prove that MHAI ThdA / ThdPhV are WYE objects whose
         // phase children are CMV SDOs, not ACD indication structures.
         [Key("MHAI", "ThdA")] = Def("MHAI", "ThdA", "WYE", 0.98, "three-phase current THD"),
         [Key("MHAI", "ThdPhV")] = Def("MHAI", "ThdPhV", "WYE", 0.98, "three-phase voltage THD"),
 
         // Instrument-transformer semantics are standardized and were also observed in
-        // the AA1E1F06R4 IEDScout engineering model. Exact registry entries prevent
+        // the field-reference engineering model. Exact registry entries prevent
         // live discovery from dropping these configuration DOs when attribute-name
         // heuristics alone cannot infer their CDC safely.
         [Key("TCTR", "Mod")] = Def("TCTR", "Mod", "ENC", 0.98, "mode control"),
diff --git a/src/AR.Iec61850/Discovery/LiveIedModelDiscoveryBuilder.cs b/src/AR.Iec61850/Discovery/LiveIedModelDiscoveryBuilder.cs
index 21025d14..744cbe56 100644
--- a/src/AR.Iec61850/Discovery/LiveIedModelDiscoveryBuilder.cs
+++ b/src/AR.Iec61850/Discovery/LiveIedModelDiscoveryBuilder.cs
@@ -215,7 +215,8 @@ private static IEnumerable<LiveIedDataObjectModel> BuildDataObjects(
                 .ToArray();
             var attrPaths = attributes.Select(x => x.AttributePath).Where(x => !string.IsNullOrWhiteSpace(x)).ToArray();
             var fcs = group.Select(x => x.FunctionalConstraint).Where(x => !string.IsNullOrWhiteSpace(x)).ToArray();
-            var cdc = CdcInferenceEngine.Infer(parsedLn.SclLnClass, group.Key, attrPaths, fcs);
+            var inferredCdc = CdcInferenceEngine.Infer(parsedLn.SclLnClass, group.Key, attrPaths, fcs);
+            var cdc = CdcInferenceEngine.RefineWithExactPrimaryType(inferredCdc, attributes);
             var reference = $"{ln.Domain}/{ln.Name}.{group.Key}";
             yield return new LiveIedDataObjectModel
             {
diff --git a/src/AR.Iec61850/Scl/Export/LiveIedSclExporter.cs b/src/AR.Iec61850/Scl/Export/LiveIedSclExporter.cs
index ae583318..0be1e0b3 100644
--- a/src/AR.Iec61850/Scl/Export/LiveIedSclExporter.cs
+++ b/src/AR.Iec61850/Scl/Export/LiveIedSclExporter.cs
@@ -877,7 +877,7 @@ private static XElement BuildDaElement(TypeTreeNode node, string ownerTypeId, Li
                     new XAttribute("type", enumTypeId));
             }
 
-            var bType = NormalizeBType(node.BType, node.Name, node.Path, cdc);
+            var bType = NormalizeBType(node.BType, node.Name, node.Path, cdc, node.TypeConfidence);
             return new XElement(
                 Scl + (isRootDa ? "DA" : "BDA"),
                 new XAttribute("name", SafeXmlName(node.Name)),
@@ -1198,7 +1198,12 @@ private static bool IsControlBlockDataObject(LiveIedDataObjectModel dataObject)
             string.Equals(attribute.FunctionalConstraint, "US", StringComparison.OrdinalIgnoreCase) ||
             string.Equals(attribute.FunctionalConstraint, "LG", StringComparison.OrdinalIgnoreCase));
 
-    private static string NormalizeBType(string bType, string name, string path, string cdc)
+    private static string NormalizeBType(
+        string bType,
+        string name,
+        string path,
+        string cdc,
+        LiveIedDiscoveryConfidenceLevel typeConfidence)
     {
         if (string.Equals(name, "q", StringComparison.OrdinalIgnoreCase))
             return "Quality";
@@ -1207,15 +1212,32 @@ private static string NormalizeBType(string bType, string name, string path, str
         if (string.Equals(name, "T", StringComparison.Ordinal))
             return "Timestamp";
 
+        var normalizedBType = (bType ?? string.Empty).Trim();
+        var exactPrimitive =
+            typeConfidence == LiveIedDiscoveryConfidenceLevel.Exact &&
+            !string.IsNullOrWhiteSpace(normalizedBType) &&
+            !normalizedBType.Equals("Unknown", StringComparison.OrdinalIgnoreCase) &&
+            !normalizedBType.Equals("Struct", StringComparison.OrdinalIgnoreCase);
+
+        // Exact MMS TypeSpecification is protocol evidence. Never overwrite it merely
+        // because a generic CDC shape inferred a different primitive type.
+        if (exactPrimitive)
+            return normalizedBType;
+
         var normalizedCdc = cdc.Trim().ToUpperInvariant();
         var normalizedPath = path.Trim();
         var inferred = InferBTypeFromCdc(normalizedCdc, name, normalizedPath);
         if (!string.IsNullOrWhiteSpace(inferred))
             return inferred;
 
-        if (string.IsNullOrWhiteSpace(bType) || string.Equals(bType, "Unknown", StringComparison.OrdinalIgnoreCase) || string.Equals(bType, "Struct", StringComparison.OrdinalIgnoreCase))
+        if (string.IsNullOrWhiteSpace(normalizedBType) ||
+            normalizedBType.Equals("Unknown", StringComparison.OrdinalIgnoreCase) ||
+            normalizedBType.Equals("Struct", StringComparison.OrdinalIgnoreCase))
+        {
             return "VisString255";
-        return bType.Trim();
+        }
+
+        return normalizedBType;
     }
 
     private static string InferBTypeFromCdc(string cdc, string name, string path)
@@ -1428,6 +1450,8 @@ private TypeTreeNode(string name, string path)
         public string Path { get; }
         public string Fc { get; private set; } = string.Empty;
         public string BType { get; private set; } = string.Empty;
+        public LiveIedDiscoveryConfidenceLevel TypeConfidence { get; private set; } =
+            LiveIedDiscoveryConfidenceLevel.Unknown;
         public IReadOnlyList<TypeTreeNode> Children => _orderedChildren;
 
         public string EffectiveFunctionalConstraint
@@ -1491,6 +1515,7 @@ private void Add(LiveIedDataAttributeModel attribute)
 
             current.Fc = attribute.FunctionalConstraint;
             current.BType = attribute.SclBType;
+            current.TypeConfidence = attribute.TypeConfidence;
         }
     }
 }
diff --git a/tests/AR.Iec61850.Tests/Scl/LiveIedSclExporterTests.cs b/tests/AR.Iec61850.Tests/Scl/LiveIedSclExporterTests.cs
index 2cb0de25..25bdf4b8 100644
--- a/tests/AR.Iec61850.Tests/Scl/LiveIedSclExporterTests.cs
+++ b/tests/AR.Iec61850.Tests/Scl/LiveIedSclExporterTests.cs
@@ -102,6 +102,109 @@ public void Exporter_Preserves_Mms_TypeSpecification_Declaration_Order_For_Statu
                 .ToArray());
     }
 
+    [Fact]
+    public void Exact_Integer_StVal_Refines_Generic_Status_To_Ins_And_Preserves_Int32()
+    {
+        var discovery = new MmsDiscoveryResult
+        {
+            IedDirectory = new MmsIedModelDirectory(
+            [
+                new MmsFcResolvedPoint
+                {
+                    Domain = "IEDADD",
+                    LogicalNode = "GGIO1",
+                    FunctionalConstraint = "ST",
+                    DataObjectPath = "UserStatus.stVal",
+                    MmsItemName = "GGIO1$ST$UserStatus$stVal"
+                },
+                new MmsFcResolvedPoint
+                {
+                    Domain = "IEDADD",
+                    LogicalNode = "GGIO1",
+                    FunctionalConstraint = "ST",
+                    DataObjectPath = "UserStatus.q",
+                    MmsItemName = "GGIO1$ST$UserStatus$q"
+                },
+                new MmsFcResolvedPoint
+                {
+                    Domain = "IEDADD",
+                    LogicalNode = "GGIO1",
+                    FunctionalConstraint = "ST",
+                    DataObjectPath = "UserStatus.t",
+                    MmsItemName = "GGIO1$ST$UserStatus$t"
+                }
+            ])
+        };
+        var typeResult = new MmsVariableAccessAttributesResult
+        {
+            IsSuccess = true,
+            Reference = new MmsObjectReference("IEDADD", "GGIO1", string.Empty),
+            TypeSpecification = new MmsTypeSpecificationNode
+            {
+                MmsType = "structure",
+                SclBType = "Struct",
+                Children =
+                [
+                    new MmsTypeSpecificationNode
+                    {
+                        Name = "ST",
+                        MmsType = "structure",
+                        SclBType = "Struct",
+                        Children =
+                        [
+                            new MmsTypeSpecificationNode
+                            {
+                                Name = "UserStatus",
+                                MmsType = "structure",
+                                SclBType = "Struct",
+                                Children =
+                                [
+                                    new MmsTypeSpecificationNode { Name = "stVal", MmsType = "integer", SclBType = "INT32" },
+                                    new MmsTypeSpecificationNode { Name = "q", MmsType = "bit-string", SclBType = "Quality" },
+                                    new MmsTypeSpecificationNode { Name = "t", MmsType = "utc-time", SclBType = "Timestamp" }
+                                ]
+                            }
+                        ]
+                    }
+                ]
+            }
+        };
+
+        var model = LiveIedModelDiscoveryBuilder.Build(
+            discovery,
+            new LiveIedModelDiscoveryBuildOptions { IedName = "IED" },
+            variableTypeAttributes: [typeResult]);
+
+        var dataObject = Assert.Single(
+            model.LogicalDevices
+                .SelectMany(device => device.LogicalNodes)
+                .SelectMany(node => node.DataObjects),
+            item => item.Name == "UserStatus");
+        Assert.Equal("INS", dataObject.InferredCdc);
+        Assert.Equal(LiveIedDiscoveryConfidenceLevel.Exact,
+            Assert.Single(dataObject.Attributes, attribute => attribute.AttributePath == "stVal").TypeConfidence);
+
+        var document = LiveIedSclExporter.BuildDocument(
+            model,
+            new LiveIedSclExportOptions { Profile = "full-model" });
+        var ns = document.Root!.Name.Namespace;
+        var lNodeType = Assert.Single(
+            document.Descendants(ns + "LNodeType"),
+            element => (string?)element.Attribute("lnClass") == "GGIO");
+        var doRef = Assert.Single(
+            lNodeType.Elements(ns + "DO"),
+            element => (string?)element.Attribute("name") == "UserStatus");
+        var doType = Assert.Single(
+            document.Descendants(ns + "DOType"),
+            element => (string?)element.Attribute("id") == (string?)doRef.Attribute("type"));
+
+        Assert.Equal("INS", (string?)doType.Attribute("cdc"));
+        var stVal = Assert.Single(
+            doType.Elements(ns + "DA"),
+            element => (string?)element.Attribute("name") == "stVal");
+        Assert.Equal("INT32", (string?)stVal.Attribute("bType"));
+    }
+
     [Fact]
     public void Exporter_Preserves_CaseDistinct_Ltrk_Cts_Members_From_Root_TypeSpecification()
     {