feat: add UseTypeSpecNext support for C# emitter pipeline

eng/emitters/scripts/Update-TypeSpecNext.ps1

@@ -0,0 +1,43 @@
+#Requires -Version 7.0
+
+<#
+.SYNOPSIS
+    Updates TypeSpec dependencies in package.json to the latest @next versions.
+
+.DESCRIPTION
+    Uses @azure-tools/typespec-bump-deps to update all TypeSpec-related dependencies
+    in the specified package.json file(s) to their latest @next versions. This script
+    only mutates the package manifest(s) — it does NOT run npm install.
+
+    The caller (typically Initialize-Repository.ps1) is responsible for running
+    npm install after this script completes.
+
+.PARAMETER PackageJsonPaths
+    One or more paths to package.json files to update. Paths are relative to the
+    current working directory.
+
+.EXAMPLE
+    ./Update-TypeSpecNext.ps1 -PackageJsonPaths "package.json"
+
+.EXAMPLE
+    ./Update-TypeSpecNext.ps1 -PackageJsonPaths "package.json", "emitter/package.json"
+#>
+
+param(
+    [Parameter(Mandatory = $true)]
+    [string[]] $PackageJsonPaths
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version 3.0
+
+. "$PSScriptRoot/CommandInvocation-Helpers.ps1"
+
+Write-Host "Updating TypeSpec dependencies to @next versions..."
+
+# Build the argument list from the provided paths
+$pathArgs = ($PackageJsonPaths | ForEach-Object { "`"$_`"" }) -join " "
+
+Invoke-LoggedCommand "npx -y @azure-tools/typespec-bump-deps@latest --use-peer-ranges $pathArgs"
+
+Write-Host "TypeSpec dependencies updated to @next versions."

packages/http-client-csharp/eng/pipeline/publish.yml

@@ -29,6 +29,11 @@ parameters:
     type: boolean
     default: true
 
+  - name: UseTypeSpecNext
+    displayName: Use TypeSpec Next (update dependencies to @next versions)
+    type: boolean
+    default: false
+
 extends:
   template: /eng/common/pipelines/templates/1es-redirect.yml
 
@@ -37,7 +42,7 @@ extends:
       - template: /eng/emitters/pipelines/templates/stages/emitter-stages.yml
         parameters:
           BuildPrereleaseVersion: true
-          UseTypeSpecNext: false
+          UseTypeSpecNext: ${{ parameters.UseTypeSpecNext }}
           Publish: ${{replace(replace('True',eq(variables['Build.SourceBranchName'], 'main'), 'public'),'True','internal')}}
           PublishDependsOnTest: ${{ parameters.RunTests }}
           PackagePath: /packages/http-client-csharp

packages/http-client-csharp/eng/scripts/Initialize-Repository.ps1

@@ -29,7 +29,9 @@ try {
         Invoke-LoggedCommand "npm ci"
     }
     elseif ($UseTypeSpecNext) {
-        # TODO: add use typespec next to template later
+        Write-Host "Updating TypeSpec dependencies to @next versions..."
+        & "$packageRoot/../../eng/emitters/scripts/Update-TypeSpecNext.ps1" -PackageJsonPaths "package.json"
+        Invoke-LoggedCommand "npm install"
     }
     else {
         Invoke-LoggedCommand "npm ci"