diff --git a/scripts/Publish-Windows.ps1 b/scripts/Publish-Windows.ps1
index 4603fb6..2d740aa 100644
--- a/scripts/Publish-Windows.ps1
+++ b/scripts/Publish-Windows.ps1
@@ -38,41 +38,12 @@ try {
         # Gravograph's serial-port runtime is not in the desktop project's dependency graph.
         if ($name -eq 'GravographIS') { Copy-Item "$staging/System.IO.Ports.dll" $package }
     }
-    $engineManifestPath = Join-Path $PSScriptRoot 'external-engines.json'
-    $engineManifest = Get-Content $engineManifestPath -Raw | ConvertFrom-Json
-    if ($engineManifest.commit -notmatch '^[0-9a-f]{40}$') { throw 'Engines must be pinned to a full commit SHA.' }
-    $engineSource = Join-Path $output 'external-engine-source'
-    git init $engineSource
-    if ($LASTEXITCODE -ne 0) { throw 'Cannot initialize engine checkout.' }
-    git -C $engineSource fetch --depth 1 $engineManifest.repository $engineManifest.commit
-    if ($LASTEXITCODE -ne 0) { throw 'Cannot fetch pinned engines.' }
-    git -C $engineSource checkout --detach FETCH_HEAD
-    if ($LASTEXITCODE -ne 0) { throw 'Cannot check out pinned engines.' }
-    $engineCommit = (git -C $engineSource rev-parse HEAD).Trim()
-    if ($LASTEXITCODE -ne 0 -or $engineCommit -ne $engineManifest.commit) { throw 'Engine source revision mismatch.' }
-    $engineDirectory = Join-Path $package 'Engines'
-    New-Item -ItemType Directory -Path $engineDirectory | Out-Null
-    # A global MSBuild property cannot be normalized by Directory.Build.props: retain the trailing slash.
-    $hostRoot = $root.Replace('\', '/') + '/'
-    foreach ($engine in $engineManifest.engines) {
-        $project = $engine.project
-        $projectDirectory = Join-Path $engineSource $project
-        dotnet test "$projectDirectory/tests/$project.Tests.csproj" -c Release "-p:OpenNestRoot=$hostRoot" "-p:Version=$Version" --logger "trx;LogFileName=$project.trx" --results-directory (Join-Path $root 'TestResults')
-        if ($LASTEXITCODE -ne 0) { throw "$project tests failed." }
-        $staging = Join-Path $output "engine-build/$project"
-        dotnet publish "$projectDirectory/$project.csproj" @common --self-contained false "-p:OpenNestRoot=$hostRoot" -o $staging
-        if ($LASTEXITCODE -ne 0) { throw "$project publish failed." }
-        Copy-Item "$staging/$project.dll" $engineDirectory
-    }
-    Copy-Item $engineManifestPath (Join-Path $engineDirectory 'manifest.json')
-    Copy-Item (Join-Path $engineSource 'LICENSE') (Join-Path $engineDirectory 'LICENSE.txt')
 
     New-Item -ItemType Directory -Path (Join-Path $package 'Schemes') -Force | Out-Null
     Copy-Item LICENSE $package
     @{
         version = $Version
         sourceCommit = $commit
-        enginesCommit = $engineCommit
         runtime = 'win-x64'
         selfContained = $true
     } | ConvertTo-Json | Set-Content (Join-Path $package 'build-info.json') -Encoding utf8NoBOM
@@ -83,10 +54,8 @@ try {
         'onnxruntime.dll', 'System.IO.Ports.dll', 'Configurations/PipeFlangeShape.json',
         'Posts/OpenNest.Posts.Cincinnati.dll', 'Posts/OpenNest.Posts.Cincinnati.json',
         'Posts/OpenNest.Posts.CincinnatiCIFiber.dll', 'Posts/OpenNest.Posts.CincinnatiCIFiber.json',
-        'Posts/OpenNest.Posts.GravographIS.dll', 'LICENSE', 'build-info.json',
-        'Engines/manifest.json', 'Engines/LICENSE.txt'
+        'Posts/OpenNest.Posts.GravographIS.dll', 'LICENSE', 'build-info.json'
     )
-    $required += $engineManifest.engines | ForEach-Object { "Engines/$($_.project).dll" }
     foreach ($file in $required) {
         if (-not (Test-Path (Join-Path $package $file) -PathType Leaf)) { throw "Package missing $file" }
     }
@@ -106,19 +75,12 @@ try {
     foreach ($file in $required) {
         if (-not (Test-Path (Join-Path $expanded $file) -PathType Leaf)) { throw "ZIP missing $file" }
     }
+    # Built-in engines ship inside OpenNest.Engine.dll: check the packaged registry, not the build tree.
     $smokeProject = Join-Path $PSScriptRoot 'ReleaseSmoke/ReleaseSmoke.csproj'
     dotnet build $smokeProject -c Release
-    if ($LASTEXITCODE -ne 0) { throw 'Engine discovery checker build failed.' }
-    # Verify silent plugin-load failure cannot be mistaken for a successful package.
-    $probe = Join-Path $expanded "Engines/$($engineManifest.engines[0].project).dll"
-    Move-Item $probe "$probe.disabled"
-    try {
-        dotnet run --project $smokeProject -c Release --no-build -- $expanded
-        if ($LASTEXITCODE -eq 0) { throw 'Missing-engine failure case was not detected.' }
-    }
-    finally { Move-Item "$probe.disabled" $probe }
+    if ($LASTEXITCODE -ne 0) { throw 'Engine registry checker build failed.' }
     dotnet run --project $smokeProject -c Release --no-build -- $expanded
-    if ($LASTEXITCODE -ne 0) { throw 'Packaged engine discovery failed.' }
+    if ($LASTEXITCODE -ne 0) { throw 'Packaged engine registry check failed.' }
 
     $process = Start-Process (Join-Path $expanded 'OpenNest.exe') -WorkingDirectory $expanded -PassThru
     try {
diff --git a/scripts/ReleaseSmoke/Program.cs b/scripts/ReleaseSmoke/Program.cs
index c024a50..06906f5 100644
--- a/scripts/ReleaseSmoke/Program.cs
+++ b/scripts/ReleaseSmoke/Program.cs
@@ -1,6 +1,5 @@
 using System.Reflection;
 using System.Runtime.Loader;
-using System.Text.Json;
 
 try
 {
@@ -15,21 +14,36 @@ try
         return File.Exists(path) ? AssemblyLoadContext.Default.LoadFromAssemblyPath(path) : null;
     };
 
-    var engineAssembly = Assembly.LoadFrom(Path.Combine(package, "OpenNest.Engine.dll"));
+    var engineAssemblyPath = Path.Combine(package, "OpenNest.Engine.dll");
+    var engineAssembly = Assembly.LoadFrom(engineAssemblyPath);
     var registry = engineAssembly.GetType("OpenNest.Engine.Jobs.NestingEngineRegistry", true)!;
-    var engineDirectory = Path.Combine(package, "Engines");
-    registry.GetMethod("LoadPlugins")!.Invoke(null, [engineDirectory]);
-    using var manifest = JsonDocument.Parse(File.ReadAllText(Path.Combine(engineDirectory, "manifest.json")));
-    foreach (var entry in manifest.RootElement.GetProperty("engines").EnumerateArray())
+    var create = registry.GetMethod("Create")!;
+
+    // Every built-in engine the desktop offers must instantiate from the packaged assembly.
+    string[] expected = ["Rectangles", "Irregular", "StockLadder", "Default", "Strip", "Vertical Remnant", "Horizontal Remnant"];
+    foreach (var name in expected)
     {
-        var name = entry.GetProperty("registryName").GetString()!;
-        var expected = Path.Combine(engineDirectory, entry.GetProperty("project").GetString() + ".dll");
-        if (!File.Exists(expected))
-            throw new FileNotFoundException("Required engine missing", expected);
-        var engine = registry.GetMethod("Create")!.Invoke(null, [name])!;
-        if (!string.Equals(engine.GetType().Assembly.Location, expected, StringComparison.OrdinalIgnoreCase))
+        var engine = create.Invoke(null, [name])!;
+        if (!string.Equals(engine.GetType().Assembly.Location, engineAssemblyPath, StringComparison.OrdinalIgnoreCase))
             throw new InvalidOperationException($"Engine {name} was not loaded from the release package.");
-        Console.WriteLine($"PASS: {name} loaded and instantiated from {expected}");
+        Console.WriteLine($"PASS: {name} instantiated from {engineAssemblyPath}");
+    }
+
+    // A selection saved before the engines were renamed must still resolve.
+    var resolved = registry.GetMethod("ResolveName")!.Invoke(null, ["Opus55NestingEngine"]);
+    if (!Equals(resolved, "Irregular"))
+        throw new InvalidOperationException($"Legacy selection Opus55NestingEngine resolved to '{resolved}', expected Irregular.");
+    Console.WriteLine("PASS: legacy selection Opus55NestingEngine resolves to Irregular");
+
+    // Failure case: an unknown engine must be rejected, so a broken registry cannot pass silently.
+    try
+    {
+        create.Invoke(null, ["ReleaseSmokeMissingEngine"]);
+        throw new InvalidOperationException("Unknown engine name was accepted.");
+    }
+    catch (TargetInvocationException exception) when (exception.InnerException is NotSupportedException)
+    {
+        Console.WriteLine("PASS: unknown engine name rejected");
     }
     return 0;
 }
diff --git a/scripts/external-engines.json b/scripts/external-engines.json
deleted file mode 100644
index 7ecdabc..0000000
--- a/scripts/external-engines.json
+++ /dev/null
@@ -1,9 +0,0 @@
-{
-  "repository": "https://git.thecozycat.net/aj/OpenNest-Engines.git",
-  "commit": "33cc2ee810a9408a4e720eecd5be30271f87d720",
-  "engines": [
-    { "project": "OpenNest.Engine.Gpt6Astra", "registryName": "Gpt6AstraNestingEngine" },
-    { "project": "OpenNest.Engine.Opus55", "registryName": "Opus55NestingEngine" },
-    { "project": "OpenNest.Engine.Qwen38FlashNext", "registryName": "Qwen38FlashNextNestingEngine" }
-  ]
-}