Support metadata parameters in body models and use methodParameterSegments for accessor paths

packages/typespec-test/test/NetworkAnalytics.Management/generated/typespec-ts/sdk/test/arm-test/src/models/models.ts

@@ -314,8 +314,8 @@ export function dataProductVersionDeserializer(item: any): DataProductVersion {
 /** The resource model definition for a Azure Resource Manager proxy resource. It will not have tags and a location */
 export interface ProxyResource extends Resource {}
 
-export function proxyResourceSerializer(item: ProxyResource): any {
-  return item;
+export function proxyResourceSerializer(_item: ProxyResource): any {
+  return {};
 }
 
 export function proxyResourceDeserializer(item: any): ProxyResource {
@@ -341,8 +341,8 @@ export interface Resource {
   readonly systemData?: SystemData;
 }
 
-export function resourceSerializer(item: Resource): any {
-  return item;
+export function resourceSerializer(_item: Resource): any {
+  return {};
 }
 
 export function resourceDeserializer(item: any): Resource {
@@ -572,8 +572,8 @@ export function dataTypeUpdatePropertiesSerializer(item: DataTypeUpdatePropertie
 /** model interface _DeleteDataRequest */
 export interface _DeleteDataRequest {}
 
-export function _deleteDataRequestSerializer(item: _DeleteDataRequest): any {
-  return item;
+export function _deleteDataRequestSerializer(_item: _DeleteDataRequest): any {
+  return {};
 }
 
 /** The details for container sas creation. */
@@ -1139,8 +1139,8 @@ export interface UserAssignedIdentity {
   readonly clientId?: string;
 }
 
-export function userAssignedIdentitySerializer(item: UserAssignedIdentity): any {
-  return item;
+export function userAssignedIdentitySerializer(_item: UserAssignedIdentity): any {
+  return {};
 }
 
 export function userAssignedIdentityDeserializer(item: any): UserAssignedIdentity {
@@ -1369,8 +1369,8 @@ export function roleAssignmentDetailDeserializer(item: any): RoleAssignmentDetai
 /** model interface _ListRolesAssignmentsRequest */
 export interface _ListRolesAssignmentsRequest {}
 
-export function _listRolesAssignmentsRequestSerializer(item: _ListRolesAssignmentsRequest): any {
-  return item;
+export function _listRolesAssignmentsRequestSerializer(_item: _ListRolesAssignmentsRequest): any {
+  return {};
 }
 
 /** list role assignments. */

packages/typespec-test/test/compute/generated/typespec-ts/src/models/compute/models.ts

@@ -48,8 +48,8 @@ export interface VirtualMachineProperties {
   readonly provisioningState?: ResourceProvisioningState;
 }
 
-export function virtualMachinePropertiesSerializer(item: VirtualMachineProperties): any {
-  return item;
+export function virtualMachinePropertiesSerializer(_item: VirtualMachineProperties): any {
+  return {};
 }
 
 export function virtualMachinePropertiesDeserializer(item: any): VirtualMachineProperties {

packages/typespec-test/test/compute/generated/typespec-ts/src/models/computeDisk/models.ts

@@ -99,8 +99,8 @@ export interface DiskProperties {
   readonly provisioningState?: ResourceProvisioningState;
 }
 
-export function diskPropertiesSerializer(item: DiskProperties): any {
-  return item;
+export function diskPropertiesSerializer(_item: DiskProperties): any {
+  return {};
 }
 
 export function diskPropertiesDeserializer(item: any): DiskProperties {
@@ -153,8 +153,8 @@ export interface DiskAccessProperties {
   readonly timeCreated?: Date;
 }
 
-export function diskAccessPropertiesSerializer(item: DiskAccessProperties): any {
-  return item;
+export function diskAccessPropertiesSerializer(_item: DiskAccessProperties): any {
+  return {};
 }
 
 export function diskAccessPropertiesDeserializer(item: any): DiskAccessProperties {

packages/typespec-test/test/compute/generated/typespec-ts/src/models/models.ts

@@ -72,8 +72,8 @@ export interface Resource {
   readonly systemData?: SystemData;
 }
 
-export function resourceSerializer(item: Resource): any {
-  return item;
+export function resourceSerializer(_item: Resource): any {
+  return {};
 }
 
 export function resourceDeserializer(item: any): Resource {

packages/typespec-ts/src/modular/emitModels.ts

@@ -732,13 +732,31 @@ function buildModelInterface(
   type: SdkModelType
 ): InterfaceDeclarationStructure {
   const flattenPropertySet = new Set<SdkModelPropertyType>();
+  // For non-input models (output-only, exception, etc.), filter out metadata
+  // properties (@header, @query, @path) since they are deserialized separately.
+  // For input models, keep metadata properties — users need to pass them.
+  const hasInputUsage = (type.usage & UsageFlags.Input) === UsageFlags.Input;
+  const isArmResource = isArmResourceModel(type);
   const interfaceStructure = {
     kind: StructureKind.Interface,
     name: normalizeModelName(context, type, NameType.Interface, true),
     isExported: true,
     properties: type.properties
-      .filter((p) => !isMetadata(context.program, p.__raw!))
       .filter((p) => {
+        if (!hasInputUsage && p.__raw && isMetadata(context.program, p.__raw)) {
+          return false;
+        }
+        // Skip the "name" metadata property on ARM resource models.
+        // ARM resource "name" is a @path property inherited from the base Resource type
+        // and is handled by the ARM infrastructure, not set by the user directly.
+        if (
+          isArmResource &&
+          p.name === "name" &&
+          p.__raw &&
+          isMetadata(context.program, p.__raw)
+        ) {
+          return false;
+        }
         // filter out the flatten property to be processed later
         if (p.flatten && p.type.kind === "model") {
           flattenPropertySet.add(p);
@@ -757,7 +775,7 @@ function buildModelInterface(
       context,
       flatten.type,
       getAllAncestors(flatten.type)
-    ).filter((p) => !isMetadata(context.program, p.__raw!));
+    );
     interfaceStructure.properties!.push(
       ...allProperties.map((p) => {
         // when the flattened property is optional, all its child properties should be optional too
@@ -932,6 +950,20 @@ export function normalizeModelName(
   return `${internalModelPrefix}${normalizeName(namespacePrefix + type.name, nameType, true)}${unionSuffix}`;
 }
 
+/**
+ * Checks if a model descends from the ARM common-types Resource base type
+ * (TrackedResource, ProxyResource, etc.) by walking the ancestor chain.
+ */
+function isArmResourceModel(type: SdkModelType): boolean {
+  const ancestors = getAllAncestors(type);
+  return ancestors.some(
+    (ancestor) =>
+      ancestor.kind === "model" &&
+      ancestor.crossLanguageDefinitionId ===
+        "Azure.ResourceManager.CommonTypes.Resource"
+  );
+}
+
 function buildModelPolymorphicType(context: SdkContext, type: SdkModelType) {
   // Only include direct subtypes in this union
   const directSubtypes = getDirectSubtypes(type);