diff --git a/package-lock.json b/package-lock.json
index 8d8c8f1c886..991acd17732 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2663,9 +2663,9 @@
       }
     },
     "node_modules/@typespec/http-client-csharp": {
-      "version": "1.0.0-alpha.20250513.4",
-      "resolved": "https://registry.npmjs.org/@typespec/http-client-csharp/-/http-client-csharp-1.0.0-alpha.20250513.4.tgz",
-      "integrity": "sha512-+XNERsDpJ/WEUWf+TWcEbS6uLMs5QCZrZ/6mi6xh9vg1wBbiQA/BEjnMFFDmXP4x4wHpYAUhvAs2jsZ0TrTr0A==",
+      "version": "1.0.0-alpha.20250521.5",
+      "resolved": "https://registry.npmjs.org/@typespec/http-client-csharp/-/http-client-csharp-1.0.0-alpha.20250521.5.tgz",
+      "integrity": "sha512-mDXJGSmIwkiOUNYyj0iWDuOaDKVX09qHNYLwAPDymKhIRV2MuYjnM62ql1Z+INvunXoI2PDVoVwHv98xwW5i6A==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -9019,7 +9019,7 @@
       "license": "MIT",
       "dependencies": {
         "@autorest/csharp": "3.0.0-beta.20240625.4",
-        "@typespec/http-client-csharp": "1.0.0-alpha.20250513.4"
+        "@typespec/http-client-csharp": "1.0.0-alpha.20250521.5"
       },
       "devDependencies": {
         "@azure-tools/typespec-autorest": "0.56.0",
diff --git a/samples/AnomalyDetector/tspCodeModel.json b/samples/AnomalyDetector/tspCodeModel.json
index a40dec3a4c4..2812854809c 100644
--- a/samples/AnomalyDetector/tspCodeModel.json
+++ b/samples/AnomalyDetector/tspCodeModel.json
@@ -1545,8 +1545,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "AnomalyDetector.Univariate.AnomalyDetectorError.x-ms-error-code",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     },
     {
      "$id": "192",
diff --git a/src/TypeSpec.Extension/Emitter.Csharp/package.json b/src/TypeSpec.Extension/Emitter.Csharp/package.json
index 0308e044422..4a34c155fd0 100644
--- a/src/TypeSpec.Extension/Emitter.Csharp/package.json
+++ b/src/TypeSpec.Extension/Emitter.Csharp/package.json
@@ -35,7 +35,7 @@
     ],
     "dependencies": {
         "@autorest/csharp": "3.0.0-beta.20240625.4",
-        "@typespec/http-client-csharp": "1.0.0-alpha.20250513.4"
+        "@typespec/http-client-csharp": "1.0.0-alpha.20250521.5"
     },
     "peerDependencies": {
         "@azure-tools/typespec-azure-core": ">=0.56.0 <1.0.0",
diff --git a/src/TypeSpec.Extension/Emitter.Csharp/src/backward-compatibility.ts b/src/TypeSpec.Extension/Emitter.Csharp/src/backward-compatibility.ts
index 00b7a7f706e..e9f74b06d9b 100644
--- a/src/TypeSpec.Extension/Emitter.Csharp/src/backward-compatibility.ts
+++ b/src/TypeSpec.Extension/Emitter.Csharp/src/backward-compatibility.ts
@@ -20,7 +20,7 @@ export function transformCodeModel(codeModel: CodeModel): CodeModel {
     for (const model of codeModel.models) {
         for (const property of model.properties) {
             // we do not do this for discriminator
-            if (property.discriminator) {
+            if (property.kind === "property" && property.discriminator) {
                 continue;
             }
             const propertyType = property.type;
diff --git a/test/CadlRanchProjects/azure/resource-manager/common-properties/tspCodeModel.json b/test/CadlRanchProjects/azure/resource-manager/common-properties/tspCodeModel.json
index 98d12d1b724..d54eb2c8b6b 100644
--- a/test/CadlRanchProjects/azure/resource-manager/common-properties/tspCodeModel.json
+++ b/test/CadlRanchProjects/azure/resource-manager/common-properties/tspCodeModel.json
@@ -700,8 +700,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.CommonProperties.ManagedIdentityTrackedResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     },
     {
      "$id": "90",
@@ -1334,8 +1336,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.CommonProperties.ConfidentialResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
diff --git a/test/CadlRanchProjects/azure/resource-manager/resources/tspCodeModel.json b/test/CadlRanchProjects/azure/resource-manager/resources/tspCodeModel.json
index aa57fd7bf00..0a0c42c9c42 100644
--- a/test/CadlRanchProjects/azure/resource-manager/resources/tspCodeModel.json
+++ b/test/CadlRanchProjects/azure/resource-manager/resources/tspCodeModel.json
@@ -854,8 +854,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.Resources.TopLevelTrackedResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
@@ -1182,8 +1184,10 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.ArmOperationStatus.id",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     },
     {
      "$id": "148",
@@ -1600,8 +1604,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.Resources.NestedProxyResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
@@ -1799,8 +1805,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.Resources.SingletonTrackedResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
@@ -2006,8 +2014,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.Resources.ExtensionsResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
@@ -2205,8 +2215,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.Resources.LocationResource.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     }
    ]
   },
diff --git a/test/CadlRanchProjects/payload/content-negotiation/tspCodeModel.json b/test/CadlRanchProjects/payload/content-negotiation/tspCodeModel.json
index b10543bcb83..88c0d600f08 100644
--- a/test/CadlRanchProjects/payload/content-negotiation/tspCodeModel.json
+++ b/test/CadlRanchProjects/payload/content-negotiation/tspCodeModel.json
@@ -67,8 +67,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Payload.ContentNegotiation.DifferentBody.PngImageAsJson.contentType",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     },
     {
      "$id": "8",
diff --git a/test/CadlRanchProjects/payload/multipart/tspCodeModel.json b/test/CadlRanchProjects/payload/multipart/tspCodeModel.json
index 7df7f91394e..6cd08da760a 100644
--- a/test/CadlRanchProjects/payload/multipart/tspCodeModel.json
+++ b/test/CadlRanchProjects/payload/multipart/tspCodeModel.json
@@ -1452,8 +1452,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Payload.MultiPart.FormData.HttpParts.NonString.float.Request.temperature.anonymous.contentType",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     }
    ]
   }
diff --git a/test/CadlRanchProjects/type/model/visibility/tspCodeModel.json b/test/CadlRanchProjects/type/model/visibility/tspCodeModel.json
index 1b484243380..eb9ae4dbf0c 100644
--- a/test/CadlRanchProjects/type/model/visibility/tspCodeModel.json
+++ b/test/CadlRanchProjects/type/model/visibility/tspCodeModel.json
@@ -58,8 +58,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Type.Model.Visibility.VisibilityModel.queryProp",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     },
     {
      "$id": "9",
diff --git a/test/CadlRanchProjectsNonAzure/payload/content-negotiation/tspCodeModel.json b/test/CadlRanchProjectsNonAzure/payload/content-negotiation/tspCodeModel.json
index 1facfe8c87e..6178f9b6c70 100644
--- a/test/CadlRanchProjectsNonAzure/payload/content-negotiation/tspCodeModel.json
+++ b/test/CadlRanchProjectsNonAzure/payload/content-negotiation/tspCodeModel.json
@@ -67,8 +67,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Payload.ContentNegotiation.DifferentBody.PngImageAsJson.contentType",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     },
     {
      "$id": "8",
diff --git a/test/CadlRanchProjectsNonAzure/payload/multipart/tspCodeModel.json b/test/CadlRanchProjectsNonAzure/payload/multipart/tspCodeModel.json
index 20c1599a0d4..46ae7016b2b 100644
--- a/test/CadlRanchProjectsNonAzure/payload/multipart/tspCodeModel.json
+++ b/test/CadlRanchProjectsNonAzure/payload/multipart/tspCodeModel.json
@@ -1452,8 +1452,7 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Payload.MultiPart.FormData.HttpParts.NonString.float.Request.temperature.anonymous.contentType",
-     "discriminator": false,
-     "flatten": false
+     "correspondingMethodParams": []
     }
    ]
   }
diff --git a/test/TestProjects/MgmtTypeSpec/tspCodeModel.json b/test/TestProjects/MgmtTypeSpec/tspCodeModel.json
index 39bd4ea68bf..6489e17af8f 100644
--- a/test/TestProjects/MgmtTypeSpec/tspCodeModel.json
+++ b/test/TestProjects/MgmtTypeSpec/tspCodeModel.json
@@ -1567,8 +1567,10 @@
          "readOnly": true,
          "decorators": [],
          "crossLanguageDefinitionId": "MgmtTypeSpec.PrivateLinkResource.name",
-         "discriminator": false,
-         "flatten": false
+         "explode": false,
+         "style": "simple",
+         "allowReserved": false,
+         "correspondingMethodParams": []
         },
         {
          "$id": "199",
@@ -2269,8 +2271,10 @@
      "readOnly": false,
      "decorators": [],
      "crossLanguageDefinitionId": "Azure.ResourceManager.ArmOperationStatus.id",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     },
     {
      "$id": "292",
@@ -2746,8 +2750,10 @@
      "readOnly": true,
      "decorators": [],
      "crossLanguageDefinitionId": "MgmtTypeSpec.Foo.name",
-     "discriminator": false,
-     "flatten": false
+     "explode": false,
+     "style": "simple",
+     "allowReserved": false,
+     "correspondingMethodParams": []
     },
     {
      "$id": "360",