diff --git a/.gitignore b/.gitignore
index 0ce6b6347db..035570ff901 100644
--- a/.gitignore
+++ b/.gitignore
@@ -217,6 +217,7 @@ packages/*/etc/
 # csharp emitter
 !packages/http-client-csharp/package-lock.json
 packages/http-client-csharp/generator/artifacts/
+packages/http-client-csharp/debug/
 packages/http-client-csharp/generated-defs/**/*.js
 packages/http-client-csharp/generated-defs/**/*.js.map
 packages/http-client-csharp/generated-defs/**/*.d.ts
diff --git a/cspell.yaml b/cspell.yaml
index 8e8883a4737..0e318d142f6 100644
--- a/cspell.yaml
+++ b/cspell.yaml
@@ -6,6 +6,8 @@ dictionaries:
   - typescript
 words:
   - Adoptium
+  - Arize
+  - arizeaiobservabilityeval
   - agentic
   - aiohttp
   - alzimmer
@@ -156,11 +158,13 @@ words:
   - myname
   - mypy
   - nanos
+  - ncpu
   - nexted
   - nihao
   - nint
   - NODEFS
   - noformat
+  - nologo
   - noopener
   - noreferrer
   - nosec
diff --git a/packages/http-client-csharp/CONTRIBUTING.md b/packages/http-client-csharp/CONTRIBUTING.md
index 53518283b9c..fad090866b7 100644
--- a/packages/http-client-csharp/CONTRIBUTING.md
+++ b/packages/http-client-csharp/CONTRIBUTING.md
@@ -176,11 +176,21 @@ Generate test projects to validate the emitter and generator:
 
 To regenerate test projects after making changes:
 
-1. **Generate projects**:
+**Generate projects**:
 
-   ```bash
-   ./eng/scripts/Generate.ps1
-   ```
+```bash
+./eng/scripts/Generate.ps1
+```
+
+### Regenerating Azure Libraries
+
+To regenerate azure libraries using your local changes, run:
+
+```bash
+   ./eng/scripts/RegenPreview.ps1 <path-to-clone-of-azure-sdk-for-net>
+```
+
+This will regenerate all the Azure libraries and allow you to view any potential diffs your changes may cause. For more information on the script's usage, see [RegenPreview](./eng/scripts/docs/RegenPreview.md).
 
 ## Creating Pull Requests
 
diff --git a/packages/http-client-csharp/eng/scripts/RegenPreview.ps1 b/packages/http-client-csharp/eng/scripts/RegenPreview.ps1
new file mode 100644
index 00000000000..07600610248
--- /dev/null
+++ b/packages/http-client-csharp/eng/scripts/RegenPreview.ps1
@@ -0,0 +1,1013 @@
+#Requires -Version 7.0
+
+<#
+.SYNOPSIS
+    Builds local generator packages and regenerates Azure SDK for .NET or OpenAI .NET libraries for validation.
+
+.DESCRIPTION
+    This script supports two modes:
+    
+    Azure SDK Mode (default):
+    1. Builds a local npm package of @typespec/http-client-csharp with a versioned name (1.0.0-alpha.YYYYMMDD.hash)
+    2. Builds and packages the three NuGet generator framework packages with the same versioning
+    3. Updates Packages.Data.props in azure-sdk-for-net with the local NuGet version
+    4. Updates the Azure generator (@azure-typespec/http-client-csharp) to use the local unbranded generator
+    5. Builds and packages the Azure generator locally
+    6. Updates the management plane generator (@azure-typespec/http-client-csharp-mgmt) to use local generators
+    7. Updates the eng folder package.json artifacts in azure-sdk-for-net
+    8. Regenerates libraries based on specified filters (all, by generator type, or interactively selected)
+    9. Restores all modified artifacts to original state on success
+    
+    OpenAI Mode (when repository path contains "openai-dotnet"):
+    1. Builds a local npm package of @typespec/http-client-csharp with a versioned name
+    2. Builds and packages the NuGet generator framework packages
+    3. Updates codegen/package.json with local unbranded generator
+    4. Updates OpenAI.Library.Plugin.csproj with local NuGet package version
+    5. Invokes Invoke-CodeGen.ps1 to regenerate the OpenAI library
+    6. Restores all modified artifacts to original state on success
+    
+    Generator Filtering (Azure SDK Mode only):
+    - Use -Azure to regenerate only Azure-branded libraries (@azure-typespec/http-client-csharp)
+    - Use -Unbranded to regenerate only unbranded libraries (@typespec/http-client-csharp)
+    - Use -Mgmt to regenerate only management plane libraries (@azure-typespec/http-client-csharp-mgmt)
+    - Omit all filter parameters to regenerate all libraries (default)
+        - Use -Select for interactive selection (can be combined with generator filters)
+
+.PARAMETER SdkLibraryRepoPath
+    Required. The local file system path to the SDK repository (azure-sdk-for-net or openai-dotnet).
+    When the path contains "openai-dotnet", the script automatically operates in OpenAI mode.
+
+.PARAMETER Select
+    Optional. Azure SDK Mode only. When specified, displays an interactive menu to select specific libraries to regenerate.
+    If omitted, regenerates all libraries without prompting.
+    Not applicable in OpenAI mode.
+
+.PARAMETER Azure
+    Optional. Azure SDK Mode only. When specified, only regenerates libraries using the Azure generator (@azure-typespec/http-client-csharp).
+    Mutually exclusive with Unbranded and Mgmt parameters.
+    Not applicable in OpenAI mode.
+
+.PARAMETER Unbranded
+    Optional. Azure SDK Mode only. When specified, only regenerates libraries using the unbranded generator (@typespec/http-client-csharp).
+    Mutually exclusive with Azure and Mgmt parameters.
+    Not applicable in OpenAI mode.
+
+.PARAMETER Mgmt
+    Optional. Azure SDK Mode only. When specified, only regenerates libraries using the management plane generator (@azure-typespec/http-client-csharp-mgmt).
+    Mutually exclusive with Azure and Unbranded parameters.
+    If no generator filter is specified, all libraries are regenerated.
+    Not applicable in OpenAI mode.
+
+.EXAMPLE
+    # Azure SDK Mode - Regenerate all libraries
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net"
+    
+.EXAMPLE
+    # OpenAI Mode - Regenerate OpenAI library
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\openai-dotnet"
+
+.EXAMPLE
+    # Azure SDK Mode - Interactively select libraries to regenerate (from all available)
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Select
+
+.EXAMPLE
+    # Regenerate only Azure-branded libraries (non-interactive)
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Azure
+
+.EXAMPLE
+    # Interactively select from Azure-branded libraries only
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Azure -Select
+
+.EXAMPLE
+    # Regenerate only unbranded libraries
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Unbranded
+
+.EXAMPLE
+    # Regenerate only management plane libraries
+    .\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Mgmt
+#>
+
+param(
+    [Parameter(Mandatory=$true)]
+    [string]$SdkLibraryRepoPath,
+    
+    [Parameter(Mandatory=$false)]
+    [switch]$Select,
+    
+    [Parameter(Mandatory=$false)]
+    [switch]$Azure,
+    
+    [Parameter(Mandatory=$false)]
+    [switch]$Unbranded,
+    
+    [Parameter(Mandatory=$false)]
+    [switch]$Mgmt
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version 3.0
+
+# Detect OpenAI mode
+$isOpenAIMode = $SdkLibraryRepoPath -like "*openai-dotnet*"
+
+# Validate mutually exclusive parameters
+if ($isOpenAIMode) {
+    # In OpenAI mode, no filter parameters are allowed
+    if ($Select -or $Azure -or $Unbranded -or $Mgmt) {
+        Write-Error "OpenAI mode detected. The -Select, -Azure, -Unbranded, and -Mgmt parameters are not applicable when regenerating OpenAI libraries."
+        exit 1
+    }
+} else {
+    # In Azure SDK mode, validate filter parameters
+    $generatorFilters = @($Azure, $Unbranded, $Mgmt)
+    $activeFilters = @($generatorFilters | Where-Object { $_ }).Count
+
+    if ($activeFilters -gt 1) {
+        Write-Error "Parameters -Azure, -Unbranded, and -Mgmt are mutually exclusive. Please specify only one."
+        exit 1
+    }
+}
+
+# Import utility functions
+Import-Module "$PSScriptRoot\Generation.psm1" -DisableNameChecking -Force
+Import-Module "$PSScriptRoot\RegenPreview.psm1" -DisableNameChecking -Force
+
+# Resolve paths
+$packageRoot = Resolve-Path (Join-Path $PSScriptRoot '..' '..')
+$sdkRepoPath = Resolve-Path $SdkLibraryRepoPath -ErrorAction Stop
+
+Write-Host "==================== LOCAL VALIDATION SCRIPT ====================" -ForegroundColor Cyan
+
+if ($isOpenAIMode) {
+    Write-Host "Repository: OpenAI .NET" -ForegroundColor Gray
+    Write-Host "Mode: OpenAI library regeneration" -ForegroundColor Yellow
+} else {
+    Write-Host "Repository: Azure SDK for .NET" -ForegroundColor Gray
+    
+    # Display active mode
+    $modeText = if ($Select) {
+        "Interactive library selection"
+    } elseif ($Azure) {
+        "Regenerate Azure SDK libraries only"
+    } elseif ($Unbranded) {
+        "Regenerate Unbranded libraries only"
+    } elseif ($Mgmt) {
+        "Regenerate Management plane libraries only"
+    } else {
+        "Regenerate ALL libraries"
+    }
+    Write-Host "Mode: $modeText" -ForegroundColor Yellow
+}
+Write-Host ""
+
+# Generate version string with timestamp and hash
+# Used for both npm and NuGet packages to ensure consistency
+function Get-LocalPackageVersion {
+    $timestamp = Get-Date -Format "yyyyMMdd"
+    $hash = (git -C $packageRoot rev-parse --short HEAD 2>$null) ?? "local"
+    return "1.0.0-alpha.$timestamp.$hash"
+}
+
+# Run npm pack and return the package file path
+function Invoke-NpmPack {
+    param(
+        [string]$WorkingDirectory,
+        [string]$DebugFolder
+    )
+    
+    Write-Host "Running: npm pack" -ForegroundColor Gray
+    Push-Location $WorkingDirectory
+    try {
+        $output = & npm pack 2>&1
+        if ($LASTEXITCODE -ne 0) {
+            throw "npm pack failed with exit code $LASTEXITCODE"
+        }
+        
+        # Get the first line that ends with .tgz (the actual package filename)
+        # It may be in format "filename: package-name.tgz" or just "package-name.tgz"
+        $packageLine = ($output | Where-Object { $_ -match '\.tgz$' } | Select-Object -First 1).ToString().Trim()
+        if ($packageLine -match 'filename:\s*(.+\.tgz)') {
+            $packageFile = $Matches[1].Trim()
+        } else {
+            $packageFile = $packageLine
+        }
+        
+        $packagePath = Join-Path $WorkingDirectory $packageFile
+        if (-not (Test-Path $packagePath)) {
+            throw "Package file not created: $packagePath"
+        }
+        
+        # Move package to debug folder
+        $debugPackagePath = Join-Path $DebugFolder $packageFile
+        Move-Item $packagePath $debugPackagePath -Force
+        
+        return $debugPackagePath
+    }
+    finally {
+        Pop-Location
+    }
+}
+
+# Update package.json with new version
+function Update-PackageJsonVersion {
+    param(
+        [string]$PackageJsonPath,
+        [string]$NewVersion
+    )
+    
+    Write-Host "Updating package version to $NewVersion in $PackageJsonPath" -ForegroundColor Gray
+    $packageJson = Get-Content $PackageJsonPath -Raw | ConvertFrom-Json -AsHashtable
+    $packageJson.version = $NewVersion
+    $packageJson | ConvertTo-Json -Depth 100 | Set-Content $PackageJsonPath -Encoding utf8 -NoNewline
+}
+
+# Update UnbrandedGeneratorVersion in Packages.Data.props
+function Update-UnbrandedGeneratorVersion {
+    param(
+        [string]$PackagesDataPropsPath,
+        [string]$NewVersion
+    )
+    
+    Write-Host "Updating UnbrandedGeneratorVersion to $NewVersion in Packages.Data.props" -ForegroundColor Gray
+    
+    $content = Get-Content $PackagesDataPropsPath -Raw
+    
+    # Use regex to find and replace the UnbrandedGeneratorVersion property
+    $pattern = '(<UnbrandedGeneratorVersion>)([^<]+)(</UnbrandedGeneratorVersion>)'
+    
+    if ($content -match $pattern) {
+        $oldVersion = $Matches[2]
+        $newContent = $content -replace $pattern, "<UnbrandedGeneratorVersion>$NewVersion</UnbrandedGeneratorVersion>"
+        Set-Content $PackagesDataPropsPath -Value $newContent -Encoding utf8 -NoNewline
+        Write-Host "  Updated UnbrandedGeneratorVersion from $oldVersion to $NewVersion" -ForegroundColor Green
+    } else {
+        throw "UnbrandedGeneratorVersion property not found in $PackagesDataPropsPath"
+    }
+}
+
+# Parse Library_Inventory.md to get libraries
+function Get-LibrariesToRegenerate {
+    param([string]$InventoryPath)
+    
+    $libraries = @()
+    $content = Get-Content $InventoryPath -Raw
+    
+    # Helper function to parse library section
+    $parseSection = {
+        param($SectionContent, $GeneratorName)
+        
+        $lines = $SectionContent -split "`n" | Where-Object { 
+            $_ -match '^\|.*\|.*\|.*\|' -and 
+            $_ -notmatch '^\|\s*Service\s*\|' -and 
+            $_ -notmatch '^\|\s*-+\s*\|' -and
+            $_.Trim() -ne ''
+        }
+        
+        $result = @()
+        foreach ($line in $lines) {
+            $parts = $line -split '\|' | ForEach-Object { $_.Trim() } | Where-Object { $_ -and $_ -notmatch '^-+$' }
+            if ($parts.Count -eq 3 -and $parts[0] -ne 'Service' -and $parts[0] -notmatch '^-+$') {
+                $result += @{
+                    Service = $parts[0]
+                    Library = $parts[1]
+                    Path = $parts[2]
+                    Generator = $GeneratorName
+                }
+            }
+        }
+        return $result
+    }
+    
+    # Parse @azure-typespec/http-client-csharp libraries
+    if ($content -match '## Data Plane Libraries using TypeSpec \(@azure-typespec/http-client-csharp\)[\s\S]*?Total: (\d+)([\s\S]*?)(?=##|\z)') {
+        $libraries += & $parseSection $Matches[2] "@azure-typespec/http-client-csharp"
+    }
+    
+    # Parse @typespec/http-client-csharp libraries
+    if ($content -match '## Data Plane Libraries using TypeSpec \(@typespec/http-client-csharp\)[\s\S]*?Total: (\d+)([\s\S]*?)(?=##|\z)') {
+        $libraries += & $parseSection $Matches[2] "@typespec/http-client-csharp"
+    }
+    
+    # Parse @azure-typespec/http-client-csharp-mgmt libraries (management plane)
+    if ($content -match '## Management Plane Libraries using TypeSpec \(@azure-typespec/http-client-csharp-mgmt\)[\s\S]*?Total: (\d+)([\s\S]*?)(?=##|\z)') {
+        $libraries += & $parseSection $Matches[2] "@azure-typespec/http-client-csharp-mgmt"
+    }
+    
+    return @($libraries)
+}
+
+# Interactive library selection
+function Select-LibrariesToRegenerate {
+    param([array]$Libraries)
+    
+    # Ensure we have an array
+    if (-not $Libraries) {
+        return @()
+    }
+    
+    $Libraries = @($Libraries)
+    
+    Write-Host "`n==================== LIBRARY SELECTION ====================" -ForegroundColor Cyan
+    Write-Host "Found $($Libraries.Count) libraries available for regeneration" -ForegroundColor White
+    Write-Host ""
+    
+    # Display libraries grouped by generator
+    $azureLibs = @($Libraries | Where-Object { $_.Generator -eq "@azure-typespec/http-client-csharp" })
+    $unbrandedLibs = @($Libraries | Where-Object { $_.Generator -eq "@typespec/http-client-csharp" })
+    $mgmtLibs = @($Libraries | Where-Object { $_.Generator -eq "@azure-typespec/http-client-csharp-mgmt" })
+    
+    $currentIndex = 1
+    
+    if ($azureLibs.Count -gt 0) {
+        Write-Host "Azure SDK Libraries:" -ForegroundColor Yellow
+        for ($i = 0; $i -lt $azureLibs.Count; $i++) {
+            $lib = $azureLibs[$i]
+            Write-Host ("  [{0,2}] {1,-50} ({2})" -f $currentIndex, $lib.Library, $lib.Service) -ForegroundColor Gray
+            $currentIndex++
+        }
+        Write-Host ""
+    }
+    
+    if ($unbrandedLibs.Count -gt 0) {
+        Write-Host "Unbranded Libraries:" -ForegroundColor Yellow
+        for ($i = 0; $i -lt $unbrandedLibs.Count; $i++) {
+            $lib = $unbrandedLibs[$i]
+            Write-Host ("  [{0,2}] {1,-50} ({2})" -f $currentIndex, $lib.Library, $lib.Service) -ForegroundColor Gray
+            $currentIndex++
+        }
+        Write-Host ""
+    }
+    
+    if ($mgmtLibs.Count -gt 0) {
+        Write-Host "Management Plane Libraries:" -ForegroundColor Yellow
+        for ($i = 0; $i -lt $mgmtLibs.Count; $i++) {
+            $lib = $mgmtLibs[$i]
+            Write-Host ("  [{0,2}] {1,-50} ({2})" -f $currentIndex, $lib.Library, $lib.Service) -ForegroundColor Gray
+            $currentIndex++
+        }
+        Write-Host ""
+    }
+    
+    Write-Host "=============================================================" -ForegroundColor Cyan
+    Write-Host ""
+    Write-Host "Enter library numbers to regenerate (comma-separated), 'all' for all libraries, or 'q' to quit:" -ForegroundColor White
+    Write-Host "Example: 1,3,5  or  1-4,7  or  all" -ForegroundColor DarkGray
+    Write-Host ""
+    
+    $selection = Read-Host "Selection"
+    
+    if ($selection -ieq 'q' -or $selection -ieq 'quit') {
+        Write-Host "Operation cancelled by user." -ForegroundColor Yellow
+        exit 0
+    }
+    
+    if ($selection -ieq 'all') {
+        return $Libraries
+    }
+    
+    # Parse selection
+    $selectedIndices = @()
+    $parts = $selection -split ',' | ForEach-Object { $_.Trim() }
+    
+    foreach ($part in $parts) {
+        if ($part -match '^(\d+)-(\d+)$') {
+            # Range: 1-4
+            $start = [int]$Matches[1]
+            $end = [int]$Matches[2]
+            $selectedIndices += ($start..$end)
+        }
+        elseif ($part -match '^\d+$') {
+            # Single number: 3
+            $selectedIndices += [int]$part
+        }
+        else {
+            Write-Host "Invalid selection format: $part" -ForegroundColor Red
+            exit 1
+        }
+    }
+    
+    # Validate and collect selected libraries
+    $selectedLibraries = @()
+    foreach ($index in $selectedIndices | Sort-Object -Unique) {
+        if ($index -lt 1 -or $index -gt $Libraries.Count) {
+            Write-Host "Invalid library number: $index (valid range: 1-$($Libraries.Count))" -ForegroundColor Red
+            exit 1
+        }
+        $selectedLibraries += $Libraries[$index - 1]
+    }
+    
+    if ($selectedLibraries.Count -eq 0) {
+        Write-Host "No libraries selected. Exiting." -ForegroundColor Yellow
+        exit 0
+    }
+    
+    Write-Host "`nSelected $($selectedLibraries.Count) libraries for regeneration:" -ForegroundColor Green
+    foreach ($lib in $selectedLibraries) {
+        Write-Host "  - $($lib.Library) ($($lib.Service))" -ForegroundColor Gray
+    }
+    Write-Host ""
+    
+    # Ensure we return an array, even for a single element
+    return @($selectedLibraries)
+}
+
+# Generate final report
+function Write-RegenerationReport {
+    param(
+        [array]$Results,
+        [TimeSpan]$ElapsedTime,
+        [string]$DebugFolder
+    )
+    
+    $passed = @($Results | Where-Object { $_.Success -eq $true })
+    $failed = @($Results | Where-Object { $_.Success -eq $false })
+    
+    Write-Host "`n==================== REGENERATION REPORT ====================" -ForegroundColor Cyan
+    Write-Host "Total Libraries: $($Results.Count)" -ForegroundColor White
+    Write-Host "Passed: $($passed.Count)" -ForegroundColor Green
+    Write-Host "Failed: $($failed.Count)" -ForegroundColor Red
+    
+    if ($ElapsedTime) {
+        $elapsedFormatted = "{0:hh\:mm\:ss}" -f $ElapsedTime
+        Write-Host "Execution Time: $elapsedFormatted" -ForegroundColor Cyan
+    }
+    Write-Host ""
+    
+    if ($passed.Count -gt 0) {
+        Write-Host "PASSED LIBRARIES:" -ForegroundColor Green
+        foreach ($result in $passed) {
+            Write-Host "  ✓ $($result.Library) ($($result.Service))" -ForegroundColor Green
+        }
+        Write-Host ""
+    }
+    
+    if ($failed.Count -gt 0) {
+        Write-Host "FAILED LIBRARIES:" -ForegroundColor Red
+        foreach ($result in $failed) {
+            Write-Host "  ✗ $($result.Library) ($($result.Service))" -ForegroundColor Red
+            Write-Host "    Error: $($result.Error)" -ForegroundColor Gray
+            if ($result.Output) {
+                Write-Host "    Details: $($result.Output.Substring(0, [Math]::Min(200, $result.Output.Length)))..." -ForegroundColor DarkGray
+            }
+        }
+        Write-Host ""
+    }
+    
+    Write-Host "=============================================================" -ForegroundColor Cyan
+    
+    # Save detailed report to debug folder
+    $reportPath = if ($DebugFolder) { 
+        Join-Path $DebugFolder "regen-report.json" 
+    } else { 
+        Join-Path $packageRoot "regen-report.json" 
+    }
+    $Results | ConvertTo-Json -Depth 10 | Set-Content $reportPath -Encoding utf8
+    Write-Host "Detailed report saved to: $reportPath" -ForegroundColor Gray
+}
+
+# ============================================================================
+# Main Script Execution
+# ============================================================================
+
+# Start timer
+$scriptStartTime = Get-Date
+
+try {
+    # Step 1: Load and select libraries (Azure SDK Mode only, if using -Select flag)
+    if ($Select -and -not $isOpenAIMode) {
+        Write-Host "`n[1/5] Loading libraries from Library_Inventory.md..." -ForegroundColor Cyan
+        
+        $inventoryPath = Join-Path $sdkRepoPath "doc" "GeneratorMigration" "Library_Inventory.md"
+        if (-not (Test-Path $inventoryPath)) {
+            throw "Library_Inventory.md not found at: $inventoryPath"
+        }
+        
+        $allLibraries = Get-LibrariesToRegenerate -InventoryPath $inventoryPath
+        
+        # Apply generator filter before interactive selection
+        $filteredLibraries = @(Filter-LibrariesByGenerator `
+            -Libraries $allLibraries `
+            -Azure:$Azure `
+            -Unbranded:$Unbranded `
+            -Mgmt:$Mgmt)
+        
+        if (-not $filteredLibraries -or $filteredLibraries.Count -eq 0) {
+            Write-Host "No libraries found matching the specified generator filter" -ForegroundColor Yellow
+            exit 0
+        }
+        
+        $libraries = @(Select-LibrariesToRegenerate -Libraries $filteredLibraries)
+        
+        # Check if user cancelled selection
+        if (-not $libraries -or $libraries.Count -eq 0) {
+            Write-Host "No libraries selected. Exiting..." -ForegroundColor Yellow
+            exit 0
+        }
+    }
+    
+    # Create debug folder for packaged artifacts with timestamped subfolder
+    $timestamp = Get-Date -Format "yyyyMMdd"
+    $debugFolder = Join-Path $packageRoot "debug" $timestamp
+    if (-not (Test-Path $debugFolder)) {
+        New-Item -ItemType Directory -Path $debugFolder -Force | Out-Null
+    }
+    
+    Write-Host "Debug folder: $debugFolder" -ForegroundColor Gray
+    Write-Host ""
+    
+    # Step 1: Build the unbranded generator
+    if ($isOpenAIMode) {
+        Write-Host "`n[1/3] Building unbranded generator..." -ForegroundColor Cyan
+    } else {
+        Write-Host "`n[2/5] Building unbranded generator..." -ForegroundColor Cyan
+    }
+    
+    Push-Location $packageRoot
+    try {
+        Write-Host "Installing dependencies..." -ForegroundColor Gray
+        Invoke "npm ci"
+        if ($LASTEXITCODE -ne 0) {
+            throw "Failed to install dependencies for unbranded generator"
+        }
+        
+        Write-Host "Cleaning build artifacts..." -ForegroundColor Gray
+        Invoke "npm run clean"
+        if ($LASTEXITCODE -ne 0) {
+            throw "Failed to clean unbranded generator"
+        }
+        
+        Write-Host "Building generator..." -ForegroundColor Gray
+        Invoke "npm run build"
+        if ($LASTEXITCODE -ne 0) {
+            throw "Failed to build unbranded generator"
+        }
+        
+        Write-Host "  Build completed" -ForegroundColor Green
+    }
+    finally {
+        Pop-Location
+    }
+    
+    # Step 2: Package the generators with local version
+    if ($isOpenAIMode) {
+        Write-Host "`n[2/3] Packaging generators..." -ForegroundColor Cyan
+    } else {
+        Write-Host "`n[2/5] Packaging generators..." -ForegroundColor Cyan
+    }
+    
+    $localVersion = Get-LocalPackageVersion
+    Write-Host "Local package version: $localVersion" -ForegroundColor Yellow
+    
+    $unbrandedPackageJson = Join-Path $packageRoot "package.json"
+    $originalPackageJson = Get-Content $unbrandedPackageJson -Raw
+    
+    try {
+        Update-PackageJsonVersion -PackageJsonPath $unbrandedPackageJson -NewVersion $localVersion
+        $unbrandedPackagePath = Invoke-NpmPack -WorkingDirectory $packageRoot -DebugFolder $debugFolder
+        Write-Host "Created npm package: $unbrandedPackagePath" -ForegroundColor Green
+    }
+    finally {
+        # Restore original package.json
+        Set-Content $unbrandedPackageJson $originalPackageJson -Encoding utf8 -NoNewline
+    }
+    
+    # Build and package NuGet packages for generator framework
+    Write-Host "Building NuGet generator packages..." -ForegroundColor Gray
+    
+    $generatorRoot = Join-Path $packageRoot "generator"
+    $nugetProjects = @(
+        "Microsoft.TypeSpec.Generator\src\Microsoft.TypeSpec.Generator.csproj",
+        "Microsoft.TypeSpec.Generator.Input\src\Microsoft.TypeSpec.Generator.Input.csproj",
+        "Microsoft.TypeSpec.Generator.ClientModel\src\Microsoft.TypeSpec.Generator.ClientModel.csproj"
+    )
+    
+    foreach ($project in $nugetProjects) {
+        $projectPath = Join-Path $generatorRoot $project
+        if (-not (Test-Path $projectPath)) {
+            throw "NuGet project not found: $projectPath"
+        }
+        
+        Write-Host "Packing: $(Split-Path $projectPath -Leaf)" -ForegroundColor Gray
+        $packCmd = "dotnet pack $projectPath /p:Version=$localVersion /p:PackageVersion=$localVersion /p:PackageOutputPath=$debugFolder --configuration Debug --no-build --nologo -v:quiet"
+        Invoke $packCmd $generatorRoot
+    }
+    
+    Write-Host "  NuGet packages created" -ForegroundColor Green
+    
+    # OpenAI Mode: Update and regenerate OpenAI library
+    if ($isOpenAIMode) {
+        Write-Host "`n[3/3] Updating and regenerating OpenAI library..." -ForegroundColor Cyan
+        
+        try {
+            $generationOutput = Update-OpenAIGenerator `
+                -OpenAIRepoPath $sdkRepoPath `
+                -UnbrandedPackagePath $unbrandedPackagePath `
+                -LocalVersion $localVersion `
+                -DebugFolder $debugFolder
+            
+            # Create result object for successful regeneration
+            $result = @{
+                Success = $true
+                Library = "OpenAI .NET Library"
+                Service = "OpenAI"
+                Path = "codegen"
+                Generator = "@typespec/http-client-csharp"
+                Error = ""
+                Output = $generationOutput
+            }
+        }
+        catch {
+            # Create result object for failed regeneration
+            $result = @{
+                Success = $false
+                Library = "OpenAI .NET Library"
+                Service = "OpenAI"
+                Path = "codegen"
+                Generator = "@typespec/http-client-csharp"
+                Error = $_.Exception.Message
+                Output = $_.Exception.ToString()
+            }
+        }
+        
+        # Calculate elapsed time and generate report
+        $scriptEndTime = Get-Date
+        $elapsedTime = $scriptEndTime - $scriptStartTime
+        
+        Write-RegenerationReport -Results @($result) -ElapsedTime $elapsedTime -DebugFolder $debugFolder
+        
+        # Exit with appropriate code
+        if ($result.Success) {
+            Write-Host "`nScript completed successfully." -ForegroundColor Cyan
+            exit 0
+        } else {
+            Write-Host "`nScript failed." -ForegroundColor Red
+            exit 1
+        }
+    }
+    
+    # Azure SDK Mode: Continue with Azure SDK-specific steps
+    
+    # Update Packages.Data.props with local NuGet version
+    $packagesDataPropsPath = Join-Path $sdkRepoPath "eng" "Packages.Data.props"
+    if (-not (Test-Path $packagesDataPropsPath)) {
+        throw "Packages.Data.props not found at: $packagesDataPropsPath"
+    }
+    
+    Update-UnbrandedGeneratorVersion -PackagesDataPropsPath $packagesDataPropsPath -NewVersion $localVersion
+    
+    # Add debug folder as a NuGet package source
+    $nugetConfigPath = Join-Path $sdkRepoPath "NuGet.Config"
+    Add-LocalNuGetSource -NuGetConfigPath $nugetConfigPath -SourcePath $debugFolder
+    
+    # Step 3: Build required generators and update artifacts
+    Write-Host "`n[3/5] Building required generators and updating artifacts..." -ForegroundColor Cyan
+    
+    # Determine which generators are needed based on libraries to be regenerated
+    if ($Select) {
+        # Libraries were already selected at the beginning
+        $librariesToAnalyze = $libraries
+    } else {
+        # Load all libraries and apply filters to determine what would be regenerated
+        $inventoryPath = Join-Path $sdkRepoPath "doc" "GeneratorMigration" "Library_Inventory.md"
+        if (-not (Test-Path $inventoryPath)) {
+            throw "Library_Inventory.md not found at: $inventoryPath"
+        }
+        
+        $allLibraries = Get-LibrariesToRegenerate -InventoryPath $inventoryPath
+        $librariesToAnalyze = Filter-LibrariesByGenerator `
+            -Libraries $allLibraries `
+            -Azure:$Azure `
+            -Unbranded:$Unbranded `
+            -Mgmt:$Mgmt
+    }
+    
+    # Determine which generators are actually needed
+    $needsUnbranded = $false
+    $needsAzure = $false
+    $needsMgmt = $false
+    
+    if ($librariesToAnalyze -and $librariesToAnalyze.Count -gt 0) {
+        foreach ($lib in $librariesToAnalyze) {
+            switch ($lib.Generator) {
+                "@typespec/http-client-csharp" { $needsUnbranded = $true }
+                "@azure-typespec/http-client-csharp" { $needsAzure = $true; $needsUnbranded = $true }
+                "@azure-typespec/http-client-csharp-mgmt" { $needsMgmt = $true; $needsAzure = $true; $needsUnbranded = $true }
+            }
+        }
+    }
+    
+    $generatorSummary = @()
+    if ($needsUnbranded) { $generatorSummary += "Unbranded" }
+    if ($needsAzure) { $generatorSummary += "Azure" }
+    if ($needsMgmt) { $generatorSummary += "Management" }
+    
+    if ($generatorSummary.Count -gt 0) {
+        Write-Host "Required generators: $($generatorSummary -join ', ')" -ForegroundColor Yellow
+    } else {
+        Write-Host "No additional generators required" -ForegroundColor Yellow
+    }
+    
+    # Update Azure generator if needed
+    if ($needsAzure) {
+        Write-Host "Building Azure generator..." -ForegroundColor Gray
+        
+        $azureGeneratorPath = Join-Path $sdkRepoPath "eng" "packages" "http-client-csharp"
+        $packagesDataPropsPath = Join-Path $sdkRepoPath "eng" "Packages.Data.props"
+        
+        $azurePackagePath = Update-AzureGenerator `
+            -AzureGeneratorPath $azureGeneratorPath `
+            -UnbrandedPackagePath $unbrandedPackagePath `
+            -DebugFolder $debugFolder `
+            -PackagesDataPropsPath $packagesDataPropsPath `
+            -LocalVersion $localVersion
+        
+        Write-Host "  Azure generator completed" -ForegroundColor Green
+    } else {
+        $azurePackagePath = $null
+    }
+    
+    # Update eng folder artifacts if needed
+    if ($needsAzure -or $needsUnbranded) {
+        Write-Host "Updating eng folder artifacts..." -ForegroundColor Gray
+        
+        $engFolder = Join-Path $sdkRepoPath "eng"
+        $tempDir = Join-Path $engFolder "temp-package-update"
+        New-Item -ItemType Directory -Path $tempDir -Force | Out-Null
+        
+        # Helper function to update emitter package files
+        $updateEmitterPackage = {
+            param($PackagePath, $EmitterJsonName, $LockJsonName)
+            
+            $emitterJson = Join-Path $engFolder $EmitterJsonName
+            $tempPackageJson = Join-Path $tempDir "package.json"
+            
+            Copy-Item $emitterJson $tempPackageJson -Force
+            
+            Push-Location $tempDir
+            try {
+                Invoke "npm install `"`"file:$PackagePath`"`" --package-lock-only" $tempDir
+                if ($LASTEXITCODE -ne 0) {
+                    throw "Failed to install local package for emitter update."
+                }
+                
+                Copy-Item $tempPackageJson $emitterJson -Force
+                $lockFile = Join-Path $tempDir "package-lock.json"
+                if (Test-Path $lockFile) {
+                    Copy-Item $lockFile (Join-Path $engFolder $LockJsonName) -Force
+                }
+                
+                # Cleanup temp files
+                Remove-Item $tempPackageJson, $lockFile -Force -ErrorAction SilentlyContinue
+            }
+            finally {
+                Pop-Location
+            }
+        }
+        
+        try {
+            if ($needsAzure -and $azurePackagePath) {
+                & $updateEmitterPackage $azurePackagePath "azure-typespec-http-client-csharp-emitter-package.json" "azure-typespec-http-client-csharp-emitter-package-lock.json"
+            }
+            
+            if ($needsUnbranded) {
+                & $updateEmitterPackage $unbrandedPackagePath "http-client-csharp-emitter-package.json" "http-client-csharp-emitter-package-lock.json"
+            }
+            
+            Write-Host "  Artifacts updated" -ForegroundColor Green
+        }
+        finally {
+            Remove-Item $tempDir -Recurse -Force -ErrorAction SilentlyContinue
+        }
+    }
+    
+    # Update management plane generator if needed
+    if ($needsMgmt) {
+        Write-Host "Building management plane generator..." -ForegroundColor Gray
+        
+        $engFolder = Join-Path $sdkRepoPath "eng"
+        $mgmtGeneratorPath = Join-Path $engFolder "packages" "http-client-csharp-mgmt"
+        
+        if (Test-Path $mgmtGeneratorPath) {
+            Update-MgmtGenerator `
+                -EngFolder $engFolder `
+                -DebugFolder $debugFolder `
+                -LocalVersion $localVersion
+            
+            Write-Host "  Management plane generator completed" -ForegroundColor Green
+        } else {
+            Write-Host "  Management plane generator not found, skipping..." -ForegroundColor Yellow
+        }
+    }
+    
+    # Step 4: Regenerate libraries
+    Write-Host "`n[4/5] Regenerating libraries..." -ForegroundColor Cyan
+    
+    if (-not $Select) {
+        # Load all libraries if not using -Select flag
+        $inventoryPath = Join-Path $sdkRepoPath "doc" "GeneratorMigration" "Library_Inventory.md"
+        if (-not (Test-Path $inventoryPath)) {
+            throw "Library_Inventory.md not found at: $inventoryPath"
+        }
+        
+        $allLibraries = Get-LibrariesToRegenerate -InventoryPath $inventoryPath
+        
+        # Apply generator filter
+        $libraries = Filter-LibrariesByGenerator `
+            -Libraries $allLibraries `
+            -Azure:$Azure `
+            -Unbranded:$Unbranded `
+            -Mgmt:$Mgmt
+        
+        if ($libraries.Count -eq 0) {
+            Write-Host "No libraries found matching the specified generator filter" -ForegroundColor Yellow
+            Write-Host "Skipping regeneration step..." -ForegroundColor Gray
+        } else {
+            $filterText = if ($Azure) {
+                " (Azure generator only)"
+            } elseif ($Unbranded) {
+                " (Unbranded generator only)"
+            } elseif ($Mgmt) {
+                " (Management plane generator only)"
+            } else {
+                ""
+            }
+            Write-Host "Regenerating $($libraries.Count) libraries$filterText" -ForegroundColor Yellow
+        }
+    } else {
+        # Libraries were already selected at the beginning
+        if ($libraries -and $libraries.Count -gt 0) {
+            Write-Host "Using $($libraries.Count) previously selected libraries" -ForegroundColor Yellow
+        } else {
+            Write-Host "No libraries were selected" -ForegroundColor Yellow
+        }
+    }
+    
+    if (-not $libraries -or $libraries.Count -eq 0) {
+        Write-Host "No libraries selected for regeneration" -ForegroundColor Yellow
+        $failedCount = 0
+    } else {
+        
+        # Determine parallel execution throttle limit: (CPU cores - 2), min 1, max 8
+        $cpuCores = if ($IsWindows -or $PSVersionTable.PSVersion.Major -lt 6) {
+            (Get-CimInstance -ClassName Win32_Processor | Measure-Object -Property NumberOfLogicalProcessors -Sum).Sum
+        } elseif ($IsMacOS) {
+            [int](sysctl -n hw.ncpu)
+        } else {
+            [int](nproc)
+        }
+        
+        $throttleLimit = [Math]::Max(1, [Math]::Min(8, $cpuCores - 2))
+        
+        Write-Host "Using $throttleLimit concurrent jobs (detected $cpuCores logical processors)" -ForegroundColor Gray
+        Write-Host ""
+        
+        # Pre-install tsp-client to avoid concurrent npm operations
+    Write-Host "Pre-installing tsp-client..." -ForegroundColor Gray
+    $tspClientDir = Join-Path $sdkRepoPath "eng" "common" "tsp-client"
+    Invoke "npm ci --prefix $tspClientDir" $tspClientDir
+    if ($LASTEXITCODE -ne 0) {
+        throw "Failed to install tsp-client"
+    }
+    Write-Host "  tsp-client ready" -ForegroundColor Green
+    Write-Host ""
+    
+    # Thread-safe collections for progress tracking
+    $completed = [System.Collections.Concurrent.ConcurrentBag[int]]::new()
+    $totalCount = $libraries.Count
+    
+    # Run regeneration in parallel
+    $results = $libraries | ForEach-Object -ThrottleLimit $throttleLimit -Parallel {
+        $library = $_
+        $azureSdkPath = $using:sdkRepoPath
+        $completedBag = $using:completed
+        $total = $using:totalCount
+        
+        # Determine build path (check for src subdirectory)
+        $libraryPath = Join-Path $azureSdkPath $library.Path
+        $srcPath = Join-Path $libraryPath "src"
+        $buildPath = if ((Test-Path $srcPath) -and (Get-ChildItem -Path $srcPath -Filter "*.csproj" -ErrorAction SilentlyContinue)) {
+            $srcPath
+        } else {
+            $libraryPath
+        }
+        
+        # Regenerate library
+        $result = try {
+            if (-not (Test-Path $libraryPath)) {
+                @{ Success = $false; Error = "Library path not found"; Output = "" }
+            } else {
+                Push-Location $buildPath
+                try {
+                    $output = & dotnet build /t:GenerateCode /p:SkipTspClientInstall=true 2>&1
+                    $exitCode = $LASTEXITCODE
+                    
+                    if ($exitCode -ne 0) {
+                        @{ Success = $false; Error = "Generation failed with exit code $exitCode"; Output = ($output -join "`n") }
+                    } else {
+                        @{ Success = $true; Output = ($output -join "`n") }
+                    }
+                }
+                finally {
+                    Pop-Location
+                }
+            }
+        }
+        catch {
+            @{ Success = $false; Error = $_.Exception.Message; Output = $_.Exception.ToString() }
+        }
+        
+        # Update progress counter
+        $completedBag.Add(1)
+        $currentCount = $completedBag.Count
+        
+        # Thread-safe console output with progress
+        $status = if ($result.Success) { "✓" } else { "✗" }
+        $color = if ($result.Success) { "Green" } else { "White" }
+        
+        $progressMsg = "[$currentCount/$total] $status $($library.Library)"
+        Write-Host $progressMsg -ForegroundColor $color
+        
+        # Return result with library metadata
+        return @{
+            Service = $library.Service
+            Library = $library.Library
+            Path = $library.Path
+            Generator = $library.Generator
+            Success = if ($result.ContainsKey('Success')) { $result.Success } else { $false }
+            Error = if ($result.ContainsKey('Error')) { $result.Error } else { "" }
+            Output = if ($result.ContainsKey('Output')) { $result.Output } else { "" }
+        }
+    }
+    
+    # Generate final report
+    $scriptEndTime = Get-Date
+    $elapsedTime = $scriptEndTime - $scriptStartTime
+    
+    Write-RegenerationReport -Results $results -ElapsedTime $elapsedTime -DebugFolder $debugFolder
+    
+    # Check if any libraries failed
+    $failedLibraries = @($results | Where-Object { -not $_.Success })
+    $failedCount = $failedLibraries.Count
+    }
+    
+    if ($failedCount -gt 0) {
+        Write-Host "`nValidation completed with warnings: $failedCount libraries failed to regenerate" -ForegroundColor Yellow
+        Write-Host "Check the detailed report above for error information" -ForegroundColor Yellow
+    } else {
+        Write-Host "`nValidation completed successfully! All libraries regenerated without errors." -ForegroundColor Green
+        
+        # Step 5: Restore artifacts to original state
+        Write-Host "`n[5/5] Restoring artifacts to original state..." -ForegroundColor Cyan
+        
+        Push-Location $sdkRepoPath
+        try {
+            Write-Host "Restoring modified files..." -ForegroundColor Gray
+            $filesToRestore = @(
+                "eng/azure-typespec-http-client-csharp-emitter-package.json"
+                "eng/azure-typespec-http-client-csharp-emitter-package-lock.json"
+                "eng/http-client-csharp-emitter-package.json"
+                "eng/http-client-csharp-emitter-package-lock.json"
+                "eng/azure-typespec-http-client-csharp-mgmt-emitter-package.json"
+                "eng/azure-typespec-http-client-csharp-mgmt-emitter-package-lock.json"
+                "eng/packages/http-client-csharp/package-lock.json"
+                "eng/packages/http-client-csharp-mgmt/package.json"
+                "eng/packages/http-client-csharp-mgmt/package-lock.json"
+                "eng/Packages.Data.props"
+                "NuGet.Config"
+            )
+            $restoreCmd = "git restore $($filesToRestore -join ' ')"
+            Invoke $restoreCmd $sdkRepoPath
+            if ($LASTEXITCODE -ne 0) {
+                throw "Failed to restore modified files"
+            }
+            Write-Host "  All artifacts restored" -ForegroundColor Green
+        }
+        finally {
+            Pop-Location
+        }
+    }
+}
+catch {
+    Write-Host "`nScript encountered an error during setup or configuration." -ForegroundColor Red
+    Write-Host $_.Exception.Message -ForegroundColor Red
+    Write-Host $_.ScriptStackTrace -ForegroundColor DarkGray
+    
+    # Attempt to restore NuGet.Config even on failure
+    Write-Host "`nAttempting to restore NuGet.Config..." -ForegroundColor Yellow
+    Push-Location $sdkRepoPath -ErrorAction SilentlyContinue
+    try {
+        #& git restore NuGet.Config 2>&1 | Out-Null
+        Invoke "git restore NuGet.Config" $sdkRepoPath
+        Write-Host "  NuGet.Config restored" -ForegroundColor Green
+    }
+    catch {
+        Write-Host "  Failed to restore NuGet.Config" -ForegroundColor Red
+    }
+    finally {
+        Pop-Location -ErrorAction SilentlyContinue
+    }
+    
+    exit 1
+}
+
+Write-Host "`nScript completed." -ForegroundColor Cyan
diff --git a/packages/http-client-csharp/eng/scripts/RegenPreview.psm1 b/packages/http-client-csharp/eng/scripts/RegenPreview.psm1
new file mode 100644
index 00000000000..9d1220faa5f
--- /dev/null
+++ b/packages/http-client-csharp/eng/scripts/RegenPreview.psm1
@@ -0,0 +1,775 @@
+Import-Module "$PSScriptRoot\Generation.psm1" -DisableNameChecking -Force -Global
+
+function Update-GeneratorPackage {
+    <#
+    .SYNOPSIS
+        Common helper function to update, build, and package a TypeSpec generator.
+
+    .DESCRIPTION
+        This internal function handles the common workflow for updating TypeSpec generators:
+        1. Updates package.json dependencies
+        2. Runs npm install
+        3. Runs npm clean to ensure a clean build
+        4. Builds the generator
+        5. Packages the generator with specified version
+        6. Moves package to debug folder
+        
+        This is a shared helper used by Update-MgmtGenerator and Update-AzureGenerator.
+
+    .PARAMETER GeneratorPath
+        Path to the generator directory.
+
+    .PARAMETER Dependencies
+        Hashtable of dependencies to update (name -> file path).
+
+    .PARAMETER DevDependencies
+        Hashtable of dev dependencies to update (name -> file path).
+
+    .PARAMETER LocalVersion
+        The version string to use for the package.
+
+    .PARAMETER DebugFolder
+        The debug folder where the package should be moved.
+
+    .PARAMETER UseNpmCi
+        If true, runs 'npm install --package-lock-only && npm ci' instead of 'npm install'.
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [string]$GeneratorPath,
+        
+        [Parameter(Mandatory=$false)]
+        [hashtable]$Dependencies = @{},
+        
+        [Parameter(Mandatory=$false)]
+        [hashtable]$DevDependencies = @{},
+        
+        [Parameter(Mandatory=$true)]
+        [string]$LocalVersion,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$DebugFolder,
+        
+        [Parameter(Mandatory=$false)]
+        [bool]$UseNpmCi = $false
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    $packageJsonPath = Join-Path $GeneratorPath "package.json"
+    $originalPackageJson = Get-Content $packageJsonPath -Raw
+
+    try {
+        # Step 1: Update package.json dependencies
+        if ($Dependencies.Count -gt 0 -or $DevDependencies.Count -gt 0) {
+            Write-Host "Updating package.json dependencies..." -ForegroundColor Gray
+            $packageJson = Get-Content $packageJsonPath -Raw | ConvertFrom-Json
+            
+            foreach ($dep in $Dependencies.GetEnumerator()) {
+                if ($packageJson.dependencies -and $packageJson.dependencies.PSObject.Properties[$dep.Key]) {
+                    $packageJson.dependencies.($dep.Key) = "file:$($dep.Value)"
+                }
+            }
+            
+            foreach ($dep in $DevDependencies.GetEnumerator()) {
+                if ($packageJson.devDependencies -and $packageJson.devDependencies.PSObject.Properties[$dep.Key]) {
+                    $packageJson.devDependencies.($dep.Key) = "file:$($dep.Value)"
+                }
+            }
+            
+            $packageJson | ConvertTo-Json -Depth 100 | Set-Content $packageJsonPath -Encoding UTF8
+            Write-Host "  Updated dependencies to local packages" -ForegroundColor Green
+        }
+
+        # Step 2: Install dependencies, clean, and build
+        Push-Location $GeneratorPath
+        try {
+            Write-Host "Installing dependencies..." -ForegroundColor Gray
+            if ($UseNpmCi) {
+                $installOutput = & npm install --package-lock-only 2>&1
+                if ($LASTEXITCODE -ne 0) {
+                    Write-Host $installOutput -ForegroundColor Red
+                    throw "Failed to update package-lock.json"
+                }
+                
+                $ciOutput = & npm ci 2>&1
+                if ($LASTEXITCODE -ne 0) {
+                    Write-Host $ciOutput -ForegroundColor Red
+                    throw "Failed to install dependencies"
+                }
+            } else {
+                $installOutput = & npm install 2>&1
+                if ($LASTEXITCODE -ne 0) {
+                    Write-Host $installOutput -ForegroundColor Red
+                    throw "Failed to run npm install"
+                }
+            }
+
+            Write-Host "Cleaning build artifacts..." -ForegroundColor Gray
+            $cleanOutput = Invoke "npm run clean" $GeneratorPath
+            if ($LASTEXITCODE -ne 0) {
+                Write-Host $cleanOutput -ForegroundColor Red
+                throw "Failed to clean generator"
+            }
+
+            Write-Host "Building generator..." -ForegroundColor Gray
+            $buildOutput = Invoke "npm run build" $GeneratorPath
+            if ($LASTEXITCODE -ne 0) {
+                Write-Host $buildOutput -ForegroundColor Red
+                throw "Failed to build generator"
+            }
+            
+            Write-Host "  Build completed" -ForegroundColor Green
+        }
+        finally {
+            Pop-Location
+        }
+
+        # Step 3: Package the generator
+        Write-Host "Packaging generator..." -ForegroundColor Gray
+        
+        # Update version in package.json for packaging
+        $packageJson = Get-Content $packageJsonPath -Raw | ConvertFrom-Json
+        $packageJson.version = $LocalVersion
+        $packageJson | ConvertTo-Json -Depth 100 | Set-Content $packageJsonPath -Encoding UTF8
+
+        Push-Location $GeneratorPath
+        try {
+            $packOutput = Invoke "npm pack" $GeneratorPath
+            if ($LASTEXITCODE -ne 0) {
+                Write-Host $packOutput -ForegroundColor Red
+                throw "Failed to pack generator"
+            }
+            
+            # Get the package filename
+            $packageLine = ($packOutput | Where-Object { $_ -match '\.tgz$' } | Select-Object -First 1).ToString().Trim()
+            if ($packageLine -match 'filename:\s*(.+\.tgz)') {
+                $packageFile = $Matches[1].Trim()
+            } else {
+                $packageFile = $packageLine
+            }
+            
+            # Move to debug folder
+            $sourcePath = Join-Path $GeneratorPath $packageFile
+            $destPath = Join-Path $DebugFolder $packageFile
+            Move-Item $sourcePath $destPath -Force
+            
+            Write-Host "  Package created: $packageFile" -ForegroundColor Green
+            
+            return $destPath
+        }
+        finally {
+            Pop-Location
+        }
+    }
+    finally {
+        # Always restore original package.json
+        Set-Content $packageJsonPath $originalPackageJson -Encoding utf8 -NoNewline
+    }
+}
+
+function Update-MgmtGenerator {
+    <#
+    .SYNOPSIS
+        Updates and builds the management plane generator (@azure-typespec/http-client-csharp-mgmt).
+
+    .DESCRIPTION
+        This function handles the management plane generator setup:
+        1. Updates package.json with local unbranded and Azure generator dependencies
+        2. Runs npm install
+        3. Runs npm run clean to ensure a clean build
+        4. Builds the management plane generator
+        5. Packages the management plane generator
+        6. Updates eng folder emitter package artifacts (azure-typespec-http-client-csharp-mgmt-emitter-package.json)
+        7. Updates mgmt emitter package artifact's devDependency for @typespec/http-client-csharp
+        
+        This function is designed to be called from RegenPreview.ps1 and uses the same
+        versioning scheme as the main generators. It derives all necessary paths from the
+        EngFolder parameter.
+
+    .PARAMETER EngFolder
+        The eng folder path in azure-sdk-for-net. All other paths (mgmt generator, 
+        package paths, Packages.Data.props) are derived from this.
+
+    .PARAMETER DebugFolder
+        The debug folder path where the packaged generators (.tgz files) are located.
+
+    .PARAMETER LocalVersion
+        The version string to use for the local package (e.g., "1.0.0-alpha.20250127.abc123").
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [string]$EngFolder,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$DebugFolder,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$LocalVersion
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    # Derive all paths from EngFolder
+    $mgmtGeneratorPath = Join-Path $EngFolder "packages" "http-client-csharp-mgmt"
+    
+    # Package paths come from debug folder
+    $azurePackageName = "azure-typespec-http-client-csharp-$LocalVersion.tgz"
+    $unbrandedPackageName = "typespec-http-client-csharp-$LocalVersion.tgz"
+    $azurePackagePath = Join-Path $DebugFolder $azurePackageName
+    $unbrandedPackagePath = Join-Path $DebugFolder $unbrandedPackageName
+    
+    if (-not (Test-Path $azurePackagePath)) {
+        throw "Azure package not found: $azurePackagePath"
+    }
+    if (-not (Test-Path $unbrandedPackagePath)) {
+        throw "Unbranded package not found: $unbrandedPackagePath"
+    }
+
+    Write-Host "Management plane generator path: $mgmtGeneratorPath" -ForegroundColor Gray
+    Write-Host "Azure package: $azurePackagePath" -ForegroundColor Gray
+    Write-Host "Unbranded package: $unbrandedPackagePath" -ForegroundColor Gray
+    Write-Host "Local version: $LocalVersion" -ForegroundColor Gray
+    Write-Host ""
+
+    # Use shared helper to build and package the mgmt generator
+    $mgmtPackagePath = Update-GeneratorPackage `
+        -GeneratorPath $mgmtGeneratorPath `
+        -Dependencies @{ '@azure-typespec/http-client-csharp' = $azurePackagePath } `
+        -DevDependencies @{ '@typespec/http-client-csharp' = $unbrandedPackagePath } `
+        -LocalVersion $LocalVersion `
+        -DebugFolder $DebugFolder `
+        -UseNpmCi $false
+
+    # Update eng folder mgmt emitter package artifacts
+    Write-Host "Updating mgmt emitter package artifacts..." -ForegroundColor Gray
+    
+    # First, update the mgmt emitter package artifact's devDependency for @typespec/http-client-csharp
+    $mgmtEmitterJson = Join-Path $EngFolder "azure-typespec-http-client-csharp-mgmt-emitter-package.json"
+    $mgmtEmitterPackageJson = Get-Content $mgmtEmitterJson -Raw | ConvertFrom-Json
+    
+    # Check if devDependencies exists and has @typespec/http-client-csharp
+    if ($mgmtEmitterPackageJson.devDependencies -and 
+        $mgmtEmitterPackageJson.devDependencies.PSObject.Properties['@typespec/http-client-csharp']) {
+        # Use file path to the unbranded package, not just the version string
+        $mgmtEmitterPackageJson.devDependencies.'@typespec/http-client-csharp' = "file:$unbrandedPackagePath"
+        $mgmtEmitterPackageJson | ConvertTo-Json -Depth 100 | Set-Content $mgmtEmitterJson -Encoding UTF8
+        Write-Host "  Updated @typespec/http-client-csharp devDependency to file:$unbrandedPackagePath" -ForegroundColor Green
+    }
+    
+    # Now update the package-lock.json with both dependencies
+    $tempDir = Join-Path $EngFolder "temp-mgmt-package-update"
+    New-Item -ItemType Directory -Path $tempDir -Force | Out-Null
+    
+    try {
+        $tempPackageJson = Join-Path $tempDir "package.json"
+        
+        Copy-Item $mgmtEmitterJson $tempPackageJson -Force
+        
+        Push-Location $tempDir
+        try {
+            # Install the mgmt package and regenerate lock file with both dependencies
+            Invoke "npm install `"`"file:$mgmtPackagePath`"`" --package-lock-only" $tempDir
+            
+            Copy-Item $tempPackageJson $mgmtEmitterJson -Force
+            $lockFile = Join-Path $tempDir "package-lock.json"
+            if (Test-Path $lockFile) {
+                $mgmtLockJson = Join-Path $EngFolder "azure-typespec-http-client-csharp-mgmt-emitter-package-lock.json"
+                Copy-Item $lockFile $mgmtLockJson -Force
+            }
+            
+            Write-Host "  Mgmt emitter package artifacts updated" -ForegroundColor Green
+        }
+        finally {
+            Pop-Location
+        }
+    }
+    finally {
+        Remove-Item $tempDir -Recurse -Force -ErrorAction SilentlyContinue
+    }
+
+    Write-Host ""
+
+    # Return the package path for potential further use
+    return $mgmtPackagePath
+}
+
+function Update-AzureGenerator {
+    <#
+    .SYNOPSIS
+        Updates and builds the Azure generator (@azure-typespec/http-client-csharp).
+
+    .DESCRIPTION
+        This function handles the Azure generator setup:
+        1. Updates package.json to use local unbranded generator dependency
+        2. Runs npm clean, install, and build
+        3. Packages the Azure generator
+        4. Builds and packages the Azure.Generator NuGet package
+        5. Updates Packages.Data.props with AzureGeneratorVersion
+        
+        This function is designed to be called from RegenPreview.ps1.
+
+    .PARAMETER AzureGeneratorPath
+        Path to the Azure generator directory in azure-sdk-for-net.
+
+    .PARAMETER UnbrandedPackagePath
+        Path to the local unbranded TypeSpec emitter package (.tgz).
+
+    .PARAMETER DebugFolder
+        The debug folder path where packaged artifacts will be stored.
+
+    .PARAMETER PackagesDataPropsPath
+        Path to the Packages.Data.props file.
+
+    .PARAMETER LocalVersion
+        The version string to use for the local package (e.g., "1.0.0-alpha.20250127.abc123").
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [string]$AzureGeneratorPath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$UnbrandedPackagePath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$DebugFolder,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$PackagesDataPropsPath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$LocalVersion
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    Write-Host "Azure generator path: $AzureGeneratorPath" -ForegroundColor Gray
+    Write-Host "Unbranded package: $UnbrandedPackagePath" -ForegroundColor Gray
+    Write-Host "Local version: $LocalVersion" -ForegroundColor Gray
+    Write-Host ""
+
+    # Use shared helper to build and package the Azure generator
+    $azurePackagePath = Update-GeneratorPackage `
+        -GeneratorPath $AzureGeneratorPath `
+        -Dependencies @{ '@typespec/http-client-csharp' = $UnbrandedPackagePath } `
+        -LocalVersion $LocalVersion `
+        -DebugFolder $DebugFolder `
+        -UseNpmCi $true
+
+    # Build and package Azure.Generator NuGet package
+    Write-Host "Packing Azure.Generator NuGet package..." -ForegroundColor Gray
+    
+    $azureGeneratorCsprojPath = Join-Path $AzureGeneratorPath "generator" "Azure.Generator" "src" "Azure.Generator.csproj"
+    if (-not (Test-Path $azureGeneratorCsprojPath)) {
+        throw "Azure.Generator project not found at: $azureGeneratorCsprojPath"
+    }
+    $packCmd = "dotnet pack `"$azureGeneratorCsprojPath`" /p:Version=$LocalVersion /p:PackageVersion=$LocalVersion /p:PackageOutputPath=`"$DebugFolder`" /p:HasReleaseVersion=`"false`" --configuration Debug --no-build --nologo -v:quiet"
+    Invoke $packCmd $AzureGeneratorPath    
+    if ($LASTEXITCODE -ne 0) {
+        throw "Failed to pack Azure.Generator"
+    }
+    
+    Write-Host "  Azure.Generator NuGet package created" -ForegroundColor Green
+
+    # Update Packages.Data.props with Azure generator version
+    Write-Host "Updating Packages.Data.props..." -ForegroundColor Gray
+    $propsContent = Get-Content $PackagesDataPropsPath -Raw
+    $pattern = '(<AzureGeneratorVersion>)([^<]+)(</AzureGeneratorVersion>)'
+    
+    if ($propsContent -match $pattern) {
+        $oldVersion = $Matches[2]
+        $newContent = $propsContent -replace $pattern, "<AzureGeneratorVersion>$LocalVersion</AzureGeneratorVersion>"
+        Set-Content $PackagesDataPropsPath -Value $newContent -Encoding utf8 -NoNewline
+        Write-Host "  Updated AzureGeneratorVersion from $oldVersion to $LocalVersion" -ForegroundColor Green
+    } else {
+        throw "AzureGeneratorVersion property not found in $PackagesDataPropsPath"
+    }
+
+    Write-Host ""
+
+    # Return the package path for potential further use
+    return $azurePackagePath
+}
+
+function Filter-LibrariesByGenerator {
+    <#
+    .SYNOPSIS
+        Filters libraries based on generator type.
+
+    .DESCRIPTION
+        This function filters a list of libraries based on the specified generator type.
+        Each library object should have a 'Generator' property.
+        If no generator filter is specified, all libraries are returned.
+
+    .PARAMETER Libraries
+        Array of library objects to filter. Each object should have a 'Generator' property.
+
+    .PARAMETER Azure
+        Filter for Azure generator (@azure-typespec/http-client-csharp).
+
+    .PARAMETER Unbranded
+        Filter for unbranded generator (@typespec/http-client-csharp).
+
+    .PARAMETER Mgmt
+        Filter for management plane generator (@azure-typespec/http-client-csharp-mgmt).
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [array]$Libraries,
+        
+        [Parameter(Mandatory=$false)]
+        [switch]$Azure,
+        
+        [Parameter(Mandatory=$false)]
+        [switch]$Unbranded,
+        
+        [Parameter(Mandatory=$false)]
+        [switch]$Mgmt
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    # If no filters specified, return everything as an array
+    if (-not $Azure -and -not $Unbranded -and -not $Mgmt) {
+        return @($Libraries)
+    }
+
+    # Filter based on specified generator type
+    $filtered = [System.Collections.ArrayList]::new()
+    
+    if ($Azure) {
+        $azureLibs = @($Libraries | Where-Object { $_.Generator -eq "@azure-typespec/http-client-csharp" })
+        foreach ($lib in $azureLibs) {
+            [void]$filtered.Add($lib)
+        }
+    }
+    
+    if ($Unbranded) {
+        $unbrandedLibs = @($Libraries | Where-Object { $_.Generator -eq "@typespec/http-client-csharp" })
+        foreach ($lib in $unbrandedLibs) {
+            [void]$filtered.Add($lib)
+        }
+    }
+    
+    if ($Mgmt) {
+        $mgmtLibs = @($Libraries | Where-Object { $_.Generator -eq "@azure-typespec/http-client-csharp-mgmt" })
+        foreach ($lib in $mgmtLibs) {
+            [void]$filtered.Add($lib)
+        }
+    }
+
+    # Return as array to ensure Count property is always available
+    return @($filtered.ToArray())
+}
+
+function Update-OpenAIGenerator {
+    <#
+    .SYNOPSIS
+        Updates and regenerates the OpenAI .NET library using local generators.
+
+    .DESCRIPTION
+        This function handles the OpenAI generator workflow:
+        1. Updates codegen/nuget.config with local NuGet package source
+        2. Updates codegen/package.json with local unbranded generator dependency
+        3. Updates OpenAI.Library.Plugin.csproj with local NuGet package version
+        4. Invokes Invoke-CodeGen.ps1 with Clean option to regenerate the library
+        
+        This function is designed to be called from RegenPreview.ps1 for OpenAI repositories.
+
+    .PARAMETER OpenAIRepoPath
+        Path to the openai-dotnet repository root.
+
+    .PARAMETER UnbrandedPackagePath
+        Path to the local unbranded TypeSpec emitter package (.tgz).
+
+    .PARAMETER LocalVersion
+        The version string to use for the local package (e.g., "1.0.0-alpha.20250127.abc123").
+
+    .PARAMETER DebugFolder
+        The debug folder path where NuGet packages are located.
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [string]$OpenAIRepoPath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$UnbrandedPackagePath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$LocalVersion,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$DebugFolder
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    Write-Host "OpenAI repository path: $OpenAIRepoPath" -ForegroundColor Gray
+    Write-Host "Unbranded package: $UnbrandedPackagePath" -ForegroundColor Gray
+    Write-Host "Local version: $LocalVersion" -ForegroundColor Gray
+    Write-Host ""
+
+    # Update root nuget.config (not codegen/nuget.config)
+    # OpenAI uses packageSourceMapping, so we need to add patterns for the generator packages
+    $nugetConfigPath = Join-Path $OpenAIRepoPath "nuget.config"
+    Add-LocalNuGetSource `
+        -NuGetConfigPath $nugetConfigPath `
+        -SourcePath $DebugFolder `
+        -PackagePatterns @(
+            "Microsoft.TypeSpec.Generator.ClientModel"
+        )
+
+    # Update codegen/package.json
+    $codegenPackageJsonPath = Join-Path $OpenAIRepoPath "codegen" "package.json"
+    if (-not (Test-Path $codegenPackageJsonPath)) {
+        throw "OpenAI codegen package.json not found: $codegenPackageJsonPath"
+    }
+
+    Write-Host "Updating OpenAI codegen package.json..." -ForegroundColor Gray
+    $originalPackageJson = Get-Content $codegenPackageJsonPath -Raw
+    
+    try {
+        $packageJson = $originalPackageJson | ConvertFrom-Json
+        
+        # Update dependencies or devDependencies with local unbranded generator
+        $updated = $false
+        
+        if ($packageJson.dependencies -and $packageJson.dependencies.PSObject.Properties['@typespec/http-client-csharp']) {
+            $packageJson.dependencies.'@typespec/http-client-csharp' = "file:$UnbrandedPackagePath"
+            $updated = $true
+            Write-Host "  Updated @typespec/http-client-csharp in dependencies to local package" -ForegroundColor Green
+        }
+        
+        if ($packageJson.devDependencies -and $packageJson.devDependencies.PSObject.Properties['@typespec/http-client-csharp']) {
+            $packageJson.devDependencies.'@typespec/http-client-csharp' = "file:$UnbrandedPackagePath"
+            $updated = $true
+            Write-Host "  Updated @typespec/http-client-csharp in devDependencies to local package" -ForegroundColor Green
+        }
+        
+        if (-not $updated) {
+            throw "@typespec/http-client-csharp not found in dependencies or devDependencies"
+        }
+        
+        $packageJson | ConvertTo-Json -Depth 100 | Set-Content $codegenPackageJsonPath -Encoding UTF8
+
+        # Delete package-lock.json to force regeneration with new dependencies
+        $packageLockPath = Join-Path $OpenAIRepoPath "codegen" "package-lock.json"
+        if (Test-Path $packageLockPath) {
+            Write-Host "Deleting codegen/package-lock.json..." -ForegroundColor Gray
+            Remove-Item $packageLockPath -Force
+        }
+
+        # Run npm install to regenerate package-lock.json with local dependencies
+        Write-Host "Installing dependencies in codegen directory..." -ForegroundColor Gray
+        Push-Location (Join-Path $OpenAIRepoPath "codegen")
+        try {
+            $npmOutput = Invoke "npm install" (Join-Path $OpenAIRepoPath "codegen")
+            if ($LASTEXITCODE -ne 0) {
+                Write-Host $npmOutput -ForegroundColor Red
+                throw "npm install failed in codegen directory"
+            }
+            Write-Host "  Dependencies installed" -ForegroundColor Green
+        }
+        finally {
+            Pop-Location
+        }
+
+        # Update OpenAI.Library.Plugin.csproj
+        $pluginCsprojPath = Join-Path $OpenAIRepoPath "codegen" "generator" "src" "OpenAI.Library.Plugin.csproj"
+        if (-not (Test-Path $pluginCsprojPath)) {
+            throw "OpenAI.Library.Plugin.csproj not found: $pluginCsprojPath"
+        }
+
+        Write-Host "Updating OpenAI.Library.Plugin.csproj..." -ForegroundColor Gray
+        [xml]$csproj = Get-Content $pluginCsprojPath
+        
+        $packageReference = $csproj.Project.ItemGroup.PackageReference | 
+            Where-Object { $_.Include -eq "Microsoft.TypeSpec.Generator.ClientModel" } | 
+            Select-Object -First 1
+        
+        if ($packageReference) {
+            $packageReference.Version = $LocalVersion
+            $csproj.Save($pluginCsprojPath)
+            Write-Host "  Updated Microsoft.TypeSpec.Generator.ClientModel to $LocalVersion" -ForegroundColor Green
+        } else {
+            throw "Microsoft.TypeSpec.Generator.ClientModel package reference not found in csproj"
+        }
+
+        # Invoke Invoke-CodeGen.ps1 with Clean option
+        $codeGenScript = Join-Path $OpenAIRepoPath "scripts" "Invoke-CodeGen.ps1"
+        if (-not (Test-Path $codeGenScript)) {
+            throw "Invoke-CodeGen.ps1 not found: $codeGenScript"
+        }
+
+        Write-Host "Generating OpenAI library code..." -ForegroundColor Gray
+        Push-Location $OpenAIRepoPath
+        try {
+            $output = & $codeGenScript -Clean 2>&1
+            if ($LASTEXITCODE -ne 0) {
+                Write-Host $output -ForegroundColor Red
+                throw "OpenAI code generation failed"
+            }
+            Write-Host "  OpenAI library regenerated successfully" -ForegroundColor Green
+            
+            # Store output for return
+            $generationOutput = $output -join "`n"
+        }
+        finally {
+            Pop-Location
+        }
+
+        # On successful regeneration, restore all modified artifacts
+        Write-Host "Restoring modified artifacts..." -ForegroundColor Gray
+        Push-Location $OpenAIRepoPath
+        try {
+            $filesToRestore = @(
+                "codegen/package.json"
+                "package-lock.json"
+                "nuget.config"
+                "codegen/generator/src/OpenAI.Library.Plugin.csproj"
+            )
+            $restoreCmd = "git restore $($filesToRestore -join ' ')"
+            Invoke $restoreCmd $OpenAIRepoPath
+
+            Write-Host "  All artifacts restored" -ForegroundColor Green
+        }
+        catch {
+            Write-Warning "Failed to restore some artifacts: $_"
+        }
+        finally {
+            Pop-Location
+        }
+    }
+    finally {
+        Pop-Location
+    }
+
+    Write-Host ""
+    
+    # Return the generation output for reporting
+    return $generationOutput
+}
+
+function Add-LocalNuGetSource {
+    <#
+    .SYNOPSIS
+        Adds a local NuGet package source to NuGet.Config.
+
+    .DESCRIPTION
+        This function adds or updates a local NuGet package source in the repository's NuGet.Config file.
+        The source is inserted after the <clear /> element if present, or appended otherwise.
+        
+        If PackagePatterns is provided, it also updates packageSourceMapping to allow the specified
+        packages to be loaded from the local source. This is required for repos that use package source mapping.
+        
+        This is a shared helper used by both Azure SDK and OpenAI workflows.
+
+    .PARAMETER NuGetConfigPath
+        Path to the NuGet.Config file.
+
+    .PARAMETER SourcePath
+        Path to the local NuGet package source directory.
+
+    .PARAMETER SourceKey
+        The key/name for the NuGet source (default: "local-codegen-debug-packages").
+
+    .PARAMETER PackagePatterns
+        Optional array of package patterns to add to packageSourceMapping for this source.
+        Example: @("Microsoft.TypeSpec.Generator*", "Azure.Generator")
+    #>
+    param(
+        [Parameter(Mandatory=$true)]
+        [string]$NuGetConfigPath,
+        
+        [Parameter(Mandatory=$true)]
+        [string]$SourcePath,
+        
+        [Parameter(Mandatory=$false)]
+        [string]$SourceKey = "local-codegen-debug-packages",
+        
+        [Parameter(Mandatory=$false)]
+        [string[]]$PackagePatterns = @()
+    )
+
+    $ErrorActionPreference = 'Stop'
+
+    if (-not (Test-Path $NuGetConfigPath)) {
+        throw "NuGet.Config not found at: $NuGetConfigPath"
+    }
+
+    Write-Host "Adding local NuGet package source to NuGet.Config..." -ForegroundColor Gray
+    [xml]$nugetConfig = Get-Content $NuGetConfigPath
+    
+    # Ensure configuration element exists
+    if (-not $nugetConfig.configuration) {
+        throw "Invalid NuGet.Config: missing <configuration> element"
+    }
+    
+    # Ensure packageSources element exists, create if needed
+    $packageSources = $nugetConfig.configuration.packageSources
+    if (-not $packageSources) {
+        $packageSources = $nugetConfig.CreateElement("packageSources")
+        $nugetConfig.configuration.AppendChild($packageSources) | Out-Null
+    }
+    
+    # Create local source element
+    $localSource = $nugetConfig.CreateElement("add")
+    $localSource.SetAttribute("key", $SourceKey)
+    $localSource.SetAttribute("value", $SourcePath)
+    
+    # Find the <clear /> element and insert after it
+    $clearElement = $packageSources.ChildNodes | Where-Object { $_.Name -eq "clear" } | Select-Object -First 1
+    
+    if ($clearElement -and $clearElement.NextSibling) {
+        $packageSources.InsertBefore($localSource, $clearElement.NextSibling) | Out-Null
+    } elseif ($clearElement) {
+        $packageSources.AppendChild($localSource) | Out-Null
+    } else {
+        # No clear element, just prepend to be first
+        if ($packageSources.FirstChild) {
+            $packageSources.InsertBefore($localSource, $packageSources.FirstChild) | Out-Null
+        } else {
+            $packageSources.AppendChild($localSource) | Out-Null
+        }
+    }
+    
+    Write-Host "  Added local NuGet source: $SourceKey" -ForegroundColor Green
+    
+    # Handle packageSourceMapping if PackagePatterns are provided
+    if ($PackagePatterns.Count -gt 0) {
+        Write-Host "  Updating packageSourceMapping..." -ForegroundColor Gray
+        
+        $packageSourceMapping = $nugetConfig.configuration.packageSourceMapping
+        if (-not $packageSourceMapping) {
+            $packageSourceMapping = $nugetConfig.CreateElement("packageSourceMapping")
+            $nugetConfig.configuration.AppendChild($packageSourceMapping) | Out-Null
+        }
+        
+        # Find or create packageSource element for our local source
+        $localPackageSource = $packageSourceMapping.packageSource | Where-Object { $_.key -eq $SourceKey } | Select-Object -First 1
+        
+        if (-not $localPackageSource) {
+            $localPackageSource = $nugetConfig.CreateElement("packageSource")
+            $localPackageSource.SetAttribute("key", $SourceKey)
+            
+            # Insert at the beginning of packageSourceMapping (highest priority)
+            if ($packageSourceMapping.FirstChild) {
+                $packageSourceMapping.InsertBefore($localPackageSource, $packageSourceMapping.FirstChild) | Out-Null
+            } else {
+                $packageSourceMapping.AppendChild($localPackageSource) | Out-Null
+            }
+        }
+        
+        # Add package patterns
+        foreach ($pattern in $PackagePatterns) {
+            $packageElement = $nugetConfig.CreateElement("package")
+            $packageElement.SetAttribute("pattern", $pattern)
+            $localPackageSource.AppendChild($packageElement) | Out-Null
+            Write-Host "    Added pattern: $pattern" -ForegroundColor Green
+        }
+    }
+    
+    $nugetConfig.Save($NuGetConfigPath)
+}
+
+Export-ModuleMember -Function "Update-MgmtGenerator", "Update-AzureGenerator", "Filter-LibrariesByGenerator", "Update-OpenAIGenerator", "Add-LocalNuGetSource"
diff --git a/packages/http-client-csharp/eng/scripts/docs/RegenPreview.md b/packages/http-client-csharp/eng/scripts/docs/RegenPreview.md
new file mode 100644
index 00000000000..38092a1b997
--- /dev/null
+++ b/packages/http-client-csharp/eng/scripts/docs/RegenPreview.md
@@ -0,0 +1,439 @@
+# RegenPreview.ps1
+
+## Overview
+
+`RegenPreview.ps1` is a PowerShell script that automates the process of building local generator packages and regenerating libraries for validation purposes. This script supports two modes:
+
+- **Azure SDK Mode**: Regenerate Azure SDK for .NET libraries
+- **OpenAI Mode**: Regenerate the OpenAI .NET library
+
+This script is designed to streamline the workflow for testing changes to the TypeSpec HTTP Client C# generator before submitting a pull request.
+
+## Purpose
+
+When making changes to the TypeSpec HTTP Client C# generator, it may be helpful to validate what the effects will be to generated libraries. This script automates the entire validation workflow by:
+
+### Azure SDK Mode
+
+1. Building local versions of the generator packages
+2. Updating the Azure SDK for .NET repository to use these local packages
+3. Regenerating all libraries (or selected libraries if `-Select` is specified)
+4. Cleaning up all modifications after validation
+
+### OpenAI Mode
+
+1. Building local version of the unbranded generator package
+2. Building local NuGet framework packages
+3. Updating the OpenAI .NET repository's codegen configuration
+4. Regenerating the OpenAI library using Invoke-CodeGen.ps1
+5. Cleaning up all modifications after validation
+
+## Prerequisites
+
+- **PowerShell 7.0 or later** (cross-platform: Windows, Linux, macOS)
+- Node.js and npm installed
+- .NET SDK installed
+- Local clone of the `typespec` repository (unbranded generator)
+- Local clone of the `azure-sdk-for-net` repository (for Azure SDK mode)
+- Local clone of the `openai-dotnet` repository (for OpenAI mode)
+
+## Usage
+
+### Azure SDK Mode - Basic Usage (Regenerate All)
+
+**Windows:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\path\to\azure-sdk-for-net"
+```
+
+**Linux/macOS:**
+
+```powershell
+./RegenPreview.ps1 -SdkLibraryRepoPath "/home/user/repos/azure-sdk-for-net"
+```
+
+This will:
+
+- Clean and build the unbranded and Azure generators with local changes
+- Regenerate **all** libraries automatically
+- Restore all modified metadata files on success (ie. package.json, package-lock.json)
+
+### OpenAI Mode - Basic Usage
+
+**Windows:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\path\to\openai-dotnet"
+```
+
+**Linux/macOS:**
+
+```powershell
+./RegenPreview.ps1 -SdkLibraryRepoPath "/home/user/repos/openai-dotnet"
+```
+
+This will:
+
+- Clean and build the unbranded generator with local changes
+- Build and package NuGet framework packages
+- Update root nuget.config with local NuGet source and packageSourceMapping
+- Update codegen/package.json with local generator
+- Regenerate codegen/package-lock.json with npm install
+- Update OpenAI.Library.Plugin.csproj with local NuGet packages
+- Regenerate the OpenAI library
+- Restore all modified generator metadata files on success
+
+**Note**: OpenAI mode is automatically detected when the repository path contains "openai-dotnet". The `-Select`, `-Azure`, `-Unbranded`, and `-Mgmt` parameters are not applicable in OpenAI mode.
+
+### Parameters
+
+#### `-SdkLibraryRepoPath` (Required)
+
+The local file system path to your SDK repository (`azure-sdk-for-net` or `openai-dotnet`). When the path contains "openai-dotnet", the script automatically operates in OpenAI mode.
+
+**Windows Example:**
+
+```powershell
+-SdkLibraryRepoPath "C:\repos\azure-sdk-for-net"
+```
+
+**Linux/macOS Example:**
+
+```powershell
+-SdkLibraryRepoPath "/home/user/repos/azure-sdk-for-net"
+```
+
+#### `-Select` (Optional)
+
+**Azure SDK Mode only.** When specified, displays an interactive menu to select specific libraries to regenerate. If omitted, all libraries are regenerated automatically.
+
+Can be combined with generator filter parameters (`-Azure`, `-Unbranded`, `-Mgmt`) to interactively select from a filtered subset.
+
+Not applicable in OpenAI mode.
+
+**Example:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Select
+```
+
+#### `-Azure` (Optional)
+
+**Azure SDK Mode only.** When specified, only regenerates libraries using the Azure-branded generator (`@azure-typespec/http-client-csharp`).
+
+Not applicable in OpenAI mode.
+
+**Example:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Azure
+```
+
+#### `-Unbranded` (Optional)
+
+**Azure SDK Mode only.** When specified, only regenerates libraries using the unbranded generator (`@typespec/http-client-csharp`).
+Not applicable in OpenAI mode.
+
+**Example:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Unbranded
+```
+
+#### `-Mgmt` (Optional)
+
+**Azure SDK Mode only.** When specified, only regenerates libraries using the management plane generator (`@azure-typespec/http-client-csharp-mgmt`).
+
+If no generator filter parameter is specified, all libraries are regenerated by default.
+
+Not applicable in OpenAI mode.
+
+**Example:**
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Mgmt
+```
+
+### Interactive Selection
+
+When running with the `-Select` flag, the script presents an interactive menu listing all available libraries:
+
+```
+==================== LIBRARY SELECTION ====================
+Found 28 libraries available for regeneration
+
+Azure-branded libraries (@azure-typespec/http-client-csharp):
+  [ 1] Azure.AI.VoiceLive                                  (ai)
+  [ 2] Azure.Data.AppConfiguration                         (appconfiguration)
+  ...
+
+Unbranded libraries (@typespec/http-client-csharp):
+  [12] Azure.AI.Projects                                   (ai)
+  [13] Azure.AI.OpenAI                                     (openai)
+
+Management plane libraries (@azure-typespec/http-client-csharp-mgmt):
+  [14] Azure.ResourceManager.AgriculturePlatform           (agricultureplatform)
+  [15] Azure.ResourceManager.ArizeAIObservabilityEval      (arizeaiobservabilityeval)
+  ...
+
+Enter library numbers to regenerate (comma-separated), 'all' for all libraries, or 'q' to quit:
+Example: 1,3,5  or  1-4,7  or  all
+```
+
+**Selection Options:**
+
+- Single library: `1`
+- Multiple libraries: `1,3,5`
+- Range of libraries: `1-4`
+- Combination: `1-4,7,10`
+- All libraries: `all`
+- Quit: `q`
+
+## How It Works
+
+The script operates in two distinct modes based on the repository path provided.
+
+### Azure SDK Mode
+
+The script performs the following steps in sequence when the repository path points to `azure-sdk-for-net`:
+
+### Step 0: Library Selection (Interactive Mode Only)
+
+- Parses `Library_Inventory.md` in the azure-sdk-for-net repository
+- Applies any generator filters if specified (`-Azure`, `-Unbranded`, `-Mgmt`)
+- Displays available libraries grouped by generator type
+- Prompts user to select which libraries to regenerate
+- Skipped when `-Select` is not specified (non-interactive mode)
+
+### Step 1: Build Unbranded Generator
+
+- Runs `npm ci` to install dependencies
+- Runs `npm run clean` to ensure a clean build
+- Runs `npm run build` to build `@typespec/http-client-csharp`
+
+### Step 2: Package Unbranded Generator
+
+- Generates a local version string: `1.0.0-alpha.YYYYMMDD.hash`
+- Updates `package.json` with the local version
+- Runs `npm pack` to create a `.tgz` package
+- Moves the package to the `debug` folder
+- Restores original `package.json`
+
+### Step 2.5: Build and Package NuGet Packages
+
+- Generates NuGet packages for three generator framework projects:
+  - `Microsoft.TypeSpec.Generator`
+  - `Microsoft.TypeSpec.Generator.Input`
+  - `Microsoft.TypeSpec.Generator.ClientModel`
+- Uses Debug configuration with `--no-build` (reuses binaries from Step 1)
+- Outputs `.nupkg` files to the `debug` folder
+- In Azure SDK mode: Updates `Packages.Data.props` and `NuGet.Config`
+- In OpenAI mode: Proceeds to Step 3 (OpenAI regeneration)
+
+---
+
+### OpenAI Mode
+
+When the repository path contains "openai-dotnet", the script switches to OpenAI mode and performs the following steps after Step 2.5:
+
+#### Step 3: Update OpenAI Generator and Regenerate
+
+**What the script does:**
+
+- Updates `nuget.config` (at the root of the repo) with local NuGet package source
+  - Adds the local debug folder as a package source
+  - Updates `packageSourceMapping` to allow Generator packages from the local source (required for OpenAI's package source mapping configuration)
+- Updates `codegen/package.json` with local unbranded generator dependency (`@typespec/http-client-csharp`)
+  - Checks both `dependencies` and `devDependencies` sections for the package
+  - Updates whichever section(s) contain the package to use `file:` protocol pointing to local `.tgz`
+- Deletes `codegen/package-lock.json` to force regeneration with new dependencies
+- Runs `npm install` in the codegen directory to regenerate the lock file with local dependencies
+- Updates `codegen/generator/src/OpenAI.Library.Plugin.csproj` with local NuGet package version for `Microsoft.TypeSpec.Generator.ClientModel`
+- Invokes `scripts/Invoke-CodeGen.ps1 -Clean` to regenerate the OpenAI library
+- **On successful regeneration**, restores all modified artifacts:
+  - `codegen/package.json`
+  - `codegen/package-lock.json`
+  - `nuget.config`
+  - `codegen/generator/src/OpenAI.Library.Plugin.csproj`
+- **On failure**, leaves all modified artifacts in place for debugging
+- Displays success message and exits
+
+**Note:** Filter parameters (`-Azure`, `-Unbranded`, `-Mgmt`, `-Select`) are not applicable in OpenAI mode and will cause an error if specified.
+
+---
+
+### Azure SDK Mode (continued)
+
+In Azure SDK mode, the script continues with additional steps after Step 2.5:
+
+### Step 3: Update and Build Azure Generator
+
+- Updates the Azure generator's `package.json` to reference the local unbranded package using `file:` protocol
+- Runs `npm run clean` to clear previous builds
+- Runs `npm install --package-lock-only` to update the lock file with the new local dependency
+- Runs `npm ci` for clean installation based on the updated lock file
+- Builds the Azure generator with `npm run build`
+
+### Step 4: Package Azure Generator
+
+- Updates `package.json` with the local version (dependency already set in Step 3)
+- Runs `npm pack` to create a `.tgz` package
+- Moves the package to the `debug` folder
+- Restores original `package.json` (after both Steps 3 and 4 complete)
+
+### Step 5: Update eng Folder Artifacts
+
+- Updates package.json artifacts in `azure-sdk-for-net/eng`:
+  - `azure-typespec-http-client-csharp-emitter-package.json`
+  - `azure-typespec-http-client-csharp-emitter-package-lock.json`
+  - `http-client-csharp-emitter-package.json`
+  - `http-client-csharp-emitter-package-lock.json`
+- Uses a temporary directory to safely update the lock files
+- These files control which generator versions are used during library regeneration
+
+### Step 6: Update and Build Management Plane Generator
+
+- Updates the management plane generator (`@azure-typespec/http-client-csharp-mgmt`) located in `azure-sdk-for-net/eng/packages/http-client-csharp-mgmt`
+- Updates `package.json` to reference both:
+  - Local Azure generator (`@azure-typespec/http-client-csharp`) using `file:` protocol
+  - Local unbranded generator (`@typespec/http-client-csharp`) using `file:` protocol
+- Runs `npm install` to install dependencies
+- Runs `npm run clean` to ensure a clean build
+- Runs `npm run build` to build the management plane generator
+- Creates a local package with `npm pack`
+- Updates eng folder emitter package artifacts:
+  - `azure-typespec-http-client-csharp-mgmt-emitter-package.json`
+  - `azure-typespec-http-client-csharp-mgmt-emitter-package-lock.json`
+- Updates `Packages.Data.props` in azure-sdk-for-net with `AzureGeneratorVersion` property
+  - This version is used by management plane libraries that reference the `Azure.Generator` NuGet package
+- This step is skipped if the management plane generator directory doesn't exist
+
+### Step 7: Prepare Library List
+
+- Confirms the list of libraries to regenerate
+- When no `-Select` flag, loads all libraries from `Library_Inventory.md` including:
+  - Data plane libraries using `@azure-typespec/http-client-csharp`
+  - Data plane libraries using `@typespec/http-client-csharp`
+  - Management plane libraries using `@azure-typespec/http-client-csharp-mgmt`
+- In interactive mode (`-Select`), uses the previously selected libraries
+
+### Step 8: Regenerate Libraries
+
+- **Pre-Install tsp-client**: Runs `npm ci --prefix eng\common\tsp-client` once before parallel execution
+  - Installs shared TypeSpec compiler tooling used by all libraries
+  - Eliminates concurrent npm conflicts during parallel regeneration
+- **Parallel Execution**: Uses PowerShell's `ForEach-Object -Parallel` to regenerate multiple libraries concurrently
+- **Cross-Platform CPU Detection**:
+  - Windows: Uses `Get-CimInstance` with `Win32_Processor`
+  - Linux: Uses `nproc` command
+  - macOS: Uses `sysctl -n hw.ncpu` command
+- **Throttle Limit**: Automatically calculated as `(CPU cores - 2)` with a minimum of 1 and maximum of 8
+- **Skip Redundant Installs**: Each parallel job uses `/p:SkipTspClientInstall=true` to skip re-installing tsp-client
+- **Thread-Safe Progress**: Real-time updates showing `[completed/total] ✓/✗ LibraryName`
+  - Success: Green with ✓
+  - Failure: White with ✗ (red reserved for error details in final report)
+- **Isolated Execution**: Each library regenerates in its own directory (no conflicts)
+- Runs `dotnet build /t:GenerateCode /p:SkipTspClientInstall=true` in the library's project directory
+- Automatically detects if the `.csproj` is in a `src` subdirectory
+- Tracks success/failure for each library with colored output
+
+### Step 9: Restore Artifacts (On Success Only)
+
+If all libraries regenerate successfully, the script restores modified files:
+
+- `eng/azure-typespec-http-client-csharp-emitter-package.json`
+- `eng/azure-typespec-http-client-csharp-emitter-package-lock.json`
+- `eng/http-client-csharp-emitter-package.json`
+- `eng/http-client-csharp-emitter-package-lock.json`
+- `eng/azure-typespec-http-client-csharp-mgmt-emitter-package.json`
+- `eng/azure-typespec-http-client-csharp-mgmt-emitter-package-lock.json`
+- `eng/packages/http-client-csharp/package-lock.json`
+- `eng/packages/http-client-csharp-mgmt/package.json`
+- `eng/packages/http-client-csharp-mgmt/package-lock.json`
+- `eng/Packages.Data.props`
+- `NuGet.Config`
+
+**Note:** If any libraries fail, artifacts are NOT restored, allowing you to debug the issue with the modified configuration intact.
+
+### Error Handling
+
+If the script encounters an error during pre-requisite steps (Steps 1-6), it will:
+
+- Display the error message and stack trace
+- Attempt to restore `NuGet.Config` to prevent leaving the repository in an inconsistent state
+- Exit with code 1
+
+## Output
+
+### Debug Folder
+
+All packaged artifacts are stored in the `debug` folder at the root of the unbranded generator:
+
+- `typespec-http-client-csharp-{version}.tgz` - Unbranded generator npm package
+- `azure-typespec-http-client-csharp-{version}.tgz` - Azure generator npm package
+- `Microsoft.TypeSpec.Generator.{version}.nupkg` - Core generator NuGet package
+- `Microsoft.TypeSpec.Generator.Input.{version}.nupkg` - Input models NuGet package
+- `Microsoft.TypeSpec.Generator.ClientModel.{version}.nupkg` - Client model NuGet package
+- `regen-report.json` - Detailed JSON report of regeneration results
+
+### Console Output
+
+The script provides colored console output with:
+
+- **Cyan**: Step headers and section dividers
+- **Yellow**: Important information (versions, library counts, warnings)
+- **Gray**: Detailed command execution and file operations
+- **Green**: Success messages
+- **Red**: Error messages and failed libraries
+- **White**: Library names during regeneration
+
+### Regeneration Report
+
+After regeneration completes, a summary report is displayed:
+
+```
+==================== REGENERATION REPORT ====================
+Total Libraries: 3
+Passed: 2
+Failed: 1
+Execution Time: 00:02:45
+
+PASSED LIBRARIES:
+  ✓ Azure.AI.VoiceLive (ai)
+  ✓ Azure.AI.Projects (cognitiveservices)
+
+FAILED LIBRARIES:
+  ✗ Azure.Messaging.EventGrid.Namespaces (eventgrid)
+    Error: Generation failed with exit code 1
+    Details: ...
+
+=============================================================
+Detailed report saved to: C:\...\debug\regen-report.json
+```
+
+## Common Scenarios
+
+### Scenario 1: Test OpenAI Library Changes
+
+```powershell
+# You made changes to the unbranded generator that affect OpenAI
+# Regenerate the OpenAI library to validate your changes
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\openai-dotnet"
+```
+
+### Scenario 2: Test a Small Change Quickly (Azure SDK)
+
+```powershell
+# You want to test Azure generator changes on specific libraries only
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net" -Select
+
+# Select just one or two libraries when prompted
+# Selection: 1,5
+```
+
+### Scenario: Full Validation Before PR
+
+```powershell
+.\RegenPreview.ps1 -SdkLibraryRepoPath "C:\repos\azure-sdk-for-net"
+```