diff --git a/Sources/SWBApplePlatform/AppIntentsMetadataTaskProducer.swift b/Sources/SWBApplePlatform/AppIntentsMetadataTaskProducer.swift
index cf8b9a03..97c53aba 100644
--- a/Sources/SWBApplePlatform/AppIntentsMetadataTaskProducer.swift
+++ b/Sources/SWBApplePlatform/AppIntentsMetadataTaskProducer.swift
@@ -49,6 +49,9 @@ final class AppIntentsMetadataTaskProducer: PhasedTaskProducer, TaskProducer {
 
     func generateTasks() async -> [any PlannedTask] {
         let tasks: [any PlannedTask] = []
+        guard let compilerSpec = self.context.appShortcutStringsMetadataCompilerSpec else {
+            return []
+        }
         guard !context.settings.globalScope.evaluate(BuiltinMacros.LM_SKIP_METADATA_EXTRACTION) else {
             return []
         }
@@ -151,7 +154,7 @@ final class AppIntentsMetadataTaskProducer: PhasedTaskProducer, TaskProducer {
                 let inputs = appShortcutStringsSources + assistantIntentsStringsSources
                 if inputs.count > 0, appShortcutStringsSources.count < 2, assistantIntentsStringsSources.count < 2 {
                     let appShortcutsMetadataCbc = CommandBuildContext(producer: self.context, scope: scope, inputs: inputs, resourcesDir: buildFilesProcessingContext.resourcesDir)
-                    await self.context.appShortcutStringsMetadataCompilerSpec.constructTasks(appShortcutsMetadataCbc, delegate)
+                    await compilerSpec.constructTasks(appShortcutsMetadataCbc, delegate)
                 }
 
                 // Only construct SSU task by default for public SDK clients. Internal default behavior should skip SSU task construction.
diff --git a/Sources/SWBApplePlatform/Specs/AppIntentsMetadata.xcspec b/Sources/SWBApplePlatform/Specs/AppIntentsMetadata.xcspec
index aa902e28..5c73889e 100644
--- a/Sources/SWBApplePlatform/Specs/AppIntentsMetadata.xcspec
+++ b/Sources/SWBApplePlatform/Specs/AppIntentsMetadata.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.appintentsmetadata";
         Name = "App Intents Metadata Extractor";
diff --git a/Sources/SWBApplePlatform/Specs/AppIntentsNLTraining.xcspec b/Sources/SWBApplePlatform/Specs/AppIntentsNLTraining.xcspec
index c7fdf563..c5f19975 100644
--- a/Sources/SWBApplePlatform/Specs/AppIntentsNLTraining.xcspec
+++ b/Sources/SWBApplePlatform/Specs/AppIntentsNLTraining.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.appintents-ssu-training";
         Name = "App Intents SSU Training Processor";
diff --git a/Sources/SWBApplePlatform/Specs/AppShortcutStringsMetadata.xcspec b/Sources/SWBApplePlatform/Specs/AppShortcutStringsMetadata.xcspec
index 8e4c3364..c587ffdb 100644
--- a/Sources/SWBApplePlatform/Specs/AppShortcutStringsMetadata.xcspec
+++ b/Sources/SWBApplePlatform/Specs/AppShortcutStringsMetadata.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.appshortcutstringsmetadata";
         Name = "App Shortcut Strings Metadata Extractor";
diff --git a/Sources/SWBApplePlatform/Specs/AssetCatalogCompiler.xcspec b/Sources/SWBApplePlatform/Specs/AssetCatalogCompiler.xcspec
index e1d5926b..a09bab73 100644
--- a/Sources/SWBApplePlatform/Specs/AssetCatalogCompiler.xcspec
+++ b/Sources/SWBApplePlatform/Specs/AssetCatalogCompiler.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = com.apple.compilers.assetcatalog;
         Name = "Asset Catalog Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/CompileSkybox.xcspec b/Sources/SWBApplePlatform/Specs/CompileSkybox.xcspec
index f381fb55..a9a2affb 100644
--- a/Sources/SWBApplePlatform/Specs/CompileSkybox.xcspec
+++ b/Sources/SWBApplePlatform/Specs/CompileSkybox.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = "com.apple.build-tasks.compile-skybox.xcplugin";
         Type = Compiler;
         Name = "Compile Skybox";
diff --git a/Sources/SWBApplePlatform/Specs/CopyPNGFile.xcspec b/Sources/SWBApplePlatform/Specs/CopyPNGFile.xcspec
index 68848f9f..64778974 100644
--- a/Sources/SWBApplePlatform/Specs/CopyPNGFile.xcspec
+++ b/Sources/SWBApplePlatform/Specs/CopyPNGFile.xcspec
@@ -12,7 +12,9 @@
 
 (
 
-    {   Type = Compiler;
+    {
+        _Domain = darwin;
+        Type = Compiler;
         Identifier = com.apple.build-tasks.copy-png-file;
         Name = "Compress PNG Files";
         Description = "Copies a .png file resource, optionally compressing it.";
diff --git a/Sources/SWBApplePlatform/Specs/CopyTiffFile.xcspec b/Sources/SWBApplePlatform/Specs/CopyTiffFile.xcspec
index 7d42cf58..49b05351 100644
--- a/Sources/SWBApplePlatform/Specs/CopyTiffFile.xcspec
+++ b/Sources/SWBApplePlatform/Specs/CopyTiffFile.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.build-tasks.copy-tiff-file;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.build-tasks.copy-tiff-file;
         Type = Compiler;
         Name = "Copy Tiff File";
         Description = "Copies a .tiff file resource with optional compression of the destination file";
diff --git a/Sources/SWBApplePlatform/Specs/CoreData.xcspec b/Sources/SWBApplePlatform/Specs/CoreData.xcspec
index ad5ab6e2..964d2e6d 100644
--- a/Sources/SWBApplePlatform/Specs/CoreData.xcspec
+++ b/Sources/SWBApplePlatform/Specs/CoreData.xcspec
@@ -89,6 +89,7 @@
         UTI = "com.apple.xcode.model.class";
     },
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.model.coredata";
         Name = "Data Model Compiler (MOMC)";
diff --git a/Sources/SWBApplePlatform/Specs/CoreML.xcspec b/Sources/SWBApplePlatform/Specs/CoreML.xcspec
index f6228ad4..65ed602c 100644
--- a/Sources/SWBApplePlatform/Specs/CoreML.xcspec
+++ b/Sources/SWBApplePlatform/Specs/CoreML.xcspec
@@ -41,6 +41,7 @@
         UTI = "com.apple.coreml.mlpackage";
     },
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.coreml";
         Name = "CoreML Model Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/EXUtil.xcspec b/Sources/SWBApplePlatform/Specs/EXUtil.xcspec
index 5c7cdd4b..b93edcf8 100644
--- a/Sources/SWBApplePlatform/Specs/EXUtil.xcspec
+++ b/Sources/SWBApplePlatform/Specs/EXUtil.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.extract-appextensionpoints";
         Name = "ExtensionPoint Extractor";
diff --git a/Sources/SWBApplePlatform/Specs/EmbeddedBinaryValidationUtility.xcspec b/Sources/SWBApplePlatform/Specs/EmbeddedBinaryValidationUtility.xcspec
index 2a93ed64..0b5414a4 100644
--- a/Sources/SWBApplePlatform/Specs/EmbeddedBinaryValidationUtility.xcspec
+++ b/Sources/SWBApplePlatform/Specs/EmbeddedBinaryValidationUtility.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Tool;
         Identifier = "com.apple.tools.validate-embedded-binary-utility";
         Name = "Embedded Binary Validation Utility";
diff --git a/Sources/SWBApplePlatform/Specs/GenerateAppPlaygroundAssetCatalog.xcspec b/Sources/SWBApplePlatform/Specs/GenerateAppPlaygroundAssetCatalog.xcspec
index d8cc96c0..888e99a5 100644
--- a/Sources/SWBApplePlatform/Specs/GenerateAppPlaygroundAssetCatalog.xcspec
+++ b/Sources/SWBApplePlatform/Specs/GenerateAppPlaygroundAssetCatalog.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Tool;
         Identifier = "com.apple.tools.generate-app-playground-asset-catalog";
         Name = "App Playground Asset Catalog Generator";
diff --git a/Sources/SWBApplePlatform/Specs/GenerateTextureAtlas.xcspec b/Sources/SWBApplePlatform/Specs/GenerateTextureAtlas.xcspec
index 77e5ecb6..534b7bbd 100644
--- a/Sources/SWBApplePlatform/Specs/GenerateTextureAtlas.xcspec
+++ b/Sources/SWBApplePlatform/Specs/GenerateTextureAtlas.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = "com.apple.build-tasks.generate-texture-atlas.xcplugin";
         Type = Compiler;
         Name = "Generate SpriteKit Texture Atlas";
diff --git a/Sources/SWBApplePlatform/Specs/IBCompiler.xcspec b/Sources/SWBApplePlatform/Specs/IBCompiler.xcspec
index 11796a4b..5e3ebbe4 100644
--- a/Sources/SWBApplePlatform/Specs/IBCompiler.xcspec
+++ b/Sources/SWBApplePlatform/Specs/IBCompiler.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.xcode.tools.ibtool.compiler";
         Name = "Interface Builder XIB Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/IBPostprocessor.xcspec b/Sources/SWBApplePlatform/Specs/IBPostprocessor.xcspec
index 6051e57f..2a58b84c 100644
--- a/Sources/SWBApplePlatform/Specs/IBPostprocessor.xcspec
+++ b/Sources/SWBApplePlatform/Specs/IBPostprocessor.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.xcode.tools.ibtool.postprocessor";
         Name = "Interface Builder NIB Postprocessor";
diff --git a/Sources/SWBApplePlatform/Specs/IBStoryboardCompiler.xcspec b/Sources/SWBApplePlatform/Specs/IBStoryboardCompiler.xcspec
index eee3e07f..eb0276f2 100644
--- a/Sources/SWBApplePlatform/Specs/IBStoryboardCompiler.xcspec
+++ b/Sources/SWBApplePlatform/Specs/IBStoryboardCompiler.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.xcode.tools.ibtool.storyboard.compiler";
         Name = "Interface Builder Storyboard Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/IBStoryboardLinker.xcspec b/Sources/SWBApplePlatform/Specs/IBStoryboardLinker.xcspec
index 4d61acd0..02aa7336 100644
--- a/Sources/SWBApplePlatform/Specs/IBStoryboardLinker.xcspec
+++ b/Sources/SWBApplePlatform/Specs/IBStoryboardLinker.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.xcode.tools.ibtool.storyboard.linker";
         Name = "Interface Builder Storyboard Linker";
diff --git a/Sources/SWBApplePlatform/Specs/IBStoryboardPostprocessor.xcspec b/Sources/SWBApplePlatform/Specs/IBStoryboardPostprocessor.xcspec
index a3d19de6..688ce44e 100644
--- a/Sources/SWBApplePlatform/Specs/IBStoryboardPostprocessor.xcspec
+++ b/Sources/SWBApplePlatform/Specs/IBStoryboardPostprocessor.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.xcode.tools.ibtool.storyboard.postprocessor";
         Name = "Interface Builder Storyboard Postprocessor";
diff --git a/Sources/SWBApplePlatform/Specs/Iconutil.xcspec b/Sources/SWBApplePlatform/Specs/Iconutil.xcspec
index b1288845..ca98ed15 100644
--- a/Sources/SWBApplePlatform/Specs/Iconutil.xcspec
+++ b/Sources/SWBApplePlatform/Specs/Iconutil.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.compilers.iconutil;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.compilers.iconutil;
         Type = Compiler;
         Name = "Iconutil";
         Description = "Icon conversion utility";
diff --git a/Sources/SWBApplePlatform/Specs/Iig.xcspec b/Sources/SWBApplePlatform/Specs/Iig.xcspec
index 1cb90337..4b419319 100644
--- a/Sources/SWBApplePlatform/Specs/Iig.xcspec
+++ b/Sources/SWBApplePlatform/Specs/Iig.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.compilers.iig;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.compilers.iig;
         Type = Compiler;
         Name = "IOKit Interface Generator";
         Description = "Invoke the 'iig' command line utility to compile an IIG file.";
diff --git a/Sources/SWBApplePlatform/Specs/InstrumentsPackage.xcspec b/Sources/SWBApplePlatform/Specs/InstrumentsPackage.xcspec
index 11cc9eba..6c2c6273 100644
--- a/Sources/SWBApplePlatform/Specs/InstrumentsPackage.xcspec
+++ b/Sources/SWBApplePlatform/Specs/InstrumentsPackage.xcspec
@@ -75,6 +75,7 @@
     },
 
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.instruments-package-builder";
         Name = "Instruments Package Builder";
diff --git a/Sources/SWBApplePlatform/Specs/Intents.xcspec b/Sources/SWBApplePlatform/Specs/Intents.xcspec
index 93de6ca1..dd071d66 100644
--- a/Sources/SWBApplePlatform/Specs/Intents.xcspec
+++ b/Sources/SWBApplePlatform/Specs/Intents.xcspec
@@ -27,6 +27,7 @@
     },
 
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.intents";
         Name = "Intent Definition Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/LSRegisterURL.xcspec b/Sources/SWBApplePlatform/Specs/LSRegisterURL.xcspec
index 35be2a90..8b0199e7 100644
--- a/Sources/SWBApplePlatform/Specs/LSRegisterURL.xcspec
+++ b/Sources/SWBApplePlatform/Specs/LSRegisterURL.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.build-tasks.ls-register-url;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.build-tasks.ls-register-url;
         Type = Compiler;
         Name = "LSRegisterURL";
         Description = "Registers the file at a URL with LaunchServices";
diff --git a/Sources/SWBApplePlatform/Specs/MetalCompiler.xcspec b/Sources/SWBApplePlatform/Specs/MetalCompiler.xcspec
index 6ef362eb..0d1de679 100644
--- a/Sources/SWBApplePlatform/Specs/MetalCompiler.xcspec
+++ b/Sources/SWBApplePlatform/Specs/MetalCompiler.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.metal";
         Name = "Metal Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/MetalLinker.xcspec b/Sources/SWBApplePlatform/Specs/MetalLinker.xcspec
index 57359ef7..221c286b 100644
--- a/Sources/SWBApplePlatform/Specs/MetalLinker.xcspec
+++ b/Sources/SWBApplePlatform/Specs/MetalLinker.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.metal-linker";
         Name = "Metal Linker";
diff --git a/Sources/SWBApplePlatform/Specs/MiG.xcspec b/Sources/SWBApplePlatform/Specs/MiG.xcspec
index d5fb8b7b..43a182fb 100644
--- a/Sources/SWBApplePlatform/Specs/MiG.xcspec
+++ b/Sources/SWBApplePlatform/Specs/MiG.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Type = Compiler;
+    {
+        _Domain = darwin;
+        Type = Compiler;
         Identifier = com.apple.compilers.mig;
         Name = "MiG";
         Description = "Mach Interface Stub Generator";
diff --git a/Sources/SWBApplePlatform/Specs/OSACompile.xcspec b/Sources/SWBApplePlatform/Specs/OSACompile.xcspec
index 0ad1eb47..4e82f5e9 100644
--- a/Sources/SWBApplePlatform/Specs/OSACompile.xcspec
+++ b/Sources/SWBApplePlatform/Specs/OSACompile.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = "com.apple.compilers.osacompile";
         Type = Compiler;
         Name = "OSACompile";
diff --git a/Sources/SWBApplePlatform/Specs/RealityAssets.xcspec b/Sources/SWBApplePlatform/Specs/RealityAssets.xcspec
index a872a5a8..c7affd00 100644
--- a/Sources/SWBApplePlatform/Specs/RealityAssets.xcspec
+++ b/Sources/SWBApplePlatform/Specs/RealityAssets.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = "com.apple.build-tasks.compile-rk-assets.xcplugin";
         Type = Compiler;
         Name = "Compile Reality Assets";
diff --git a/Sources/SWBApplePlatform/Specs/ReferenceObject.xcspec b/Sources/SWBApplePlatform/Specs/ReferenceObject.xcspec
index e90168e0..2db1c3bc 100644
--- a/Sources/SWBApplePlatform/Specs/ReferenceObject.xcspec
+++ b/Sources/SWBApplePlatform/Specs/ReferenceObject.xcspec
@@ -25,6 +25,7 @@
         UTI = "com.apple.arkit.referenceobject";
     },
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.referenceobject";
         Name = "Reference Object Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/ResMerger.xcspec b/Sources/SWBApplePlatform/Specs/ResMerger.xcspec
index c74c64f3..3329456d 100644
--- a/Sources/SWBApplePlatform/Specs/ResMerger.xcspec
+++ b/Sources/SWBApplePlatform/Specs/ResMerger.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Type = Linker;
+    {
+        _Domain = darwin;
+        Type = Linker;
         Identifier = com.apple.pbx.linkers.resmerger;
         Name = "ResMerger";
         Description = "Create a Carbon resource file using Apple's Carbon Resource Merger";
diff --git a/Sources/SWBApplePlatform/Specs/Rez.xcspec b/Sources/SWBApplePlatform/Specs/Rez.xcspec
index f514d1bb..4de7bea3 100644
--- a/Sources/SWBApplePlatform/Specs/Rez.xcspec
+++ b/Sources/SWBApplePlatform/Specs/Rez.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.compilers.rez;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.compilers.rez;
         Type = Tool;
         Name = "Rez";
         Description = "Resource Manager Resource Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/SceneKitTools.xcspec b/Sources/SWBApplePlatform/Specs/SceneKitTools.xcspec
index 3612daed..ce8beaa8 100644
--- a/Sources/SWBApplePlatform/Specs/SceneKitTools.xcspec
+++ b/Sources/SWBApplePlatform/Specs/SceneKitTools.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = "com.apple.compilers.scntool";
         Type = Compiler;
         Name = "Process SceneKit Document";
@@ -73,6 +74,7 @@
         );
     },
     {
+        _Domain = darwin;
         Identifier = "com.apple.build-tasks.copy-scenekit-assets";
         Type = Compiler;
         Name = "Copy SceneKit Assets";
@@ -138,6 +140,7 @@
     },
 
     {
+        _Domain = darwin;
         Identifier = "com.apple.build-tasks.compile-scenekit-shadercache";
         Type = Compiler;
         Name = "Compile SceneKit Shaders";
diff --git a/Sources/SWBApplePlatform/Specs/TiffUtil.xcspec b/Sources/SWBApplePlatform/Specs/TiffUtil.xcspec
index ae41471b..1fa6b46a 100644
--- a/Sources/SWBApplePlatform/Specs/TiffUtil.xcspec
+++ b/Sources/SWBApplePlatform/Specs/TiffUtil.xcspec
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 (
-    {   Identifier = com.apple.compilers.tiffutil;
+    {
+        _Domain = darwin;
+        Identifier = com.apple.compilers.tiffutil;
         Type = Compiler;
         Name = "TiffUtil";
         Description = "Combine a set of images at different resolutions into one HiDPI compliant file using TiffUtil";
diff --git a/Sources/SWBApplePlatform/Specs/XCAppExtensionPoints.xcspec b/Sources/SWBApplePlatform/Specs/XCAppExtensionPoints.xcspec
index 3c7e81b2..ca052496 100644
--- a/Sources/SWBApplePlatform/Specs/XCAppExtensionPoints.xcspec
+++ b/Sources/SWBApplePlatform/Specs/XCAppExtensionPoints.xcspec
@@ -12,6 +12,7 @@
 
 (
     {
+        _Domain = darwin;
         Identifier = com.apple.compilers.process-xcappextensionpoints;
         Type = Compiler;
         Name = "Process XCAppExtensionPoints";
diff --git a/Sources/SWBApplePlatform/Specs/XCStrings.xcspec b/Sources/SWBApplePlatform/Specs/XCStrings.xcspec
index be6e2a4f..75648eb4 100644
--- a/Sources/SWBApplePlatform/Specs/XCStrings.xcspec
+++ b/Sources/SWBApplePlatform/Specs/XCStrings.xcspec
@@ -26,6 +26,7 @@
     },
 
     {
+        _Domain = darwin;
         Type = Compiler;
         Identifier = "com.apple.compilers.xcstrings";
         Name = "XCStrings Compiler";
diff --git a/Sources/SWBApplePlatform/Specs/tvOSShared.xcspec b/Sources/SWBApplePlatform/Specs/tvOSShared.xcspec
index 92498be6..5391c4e8 100644
--- a/Sources/SWBApplePlatform/Specs/tvOSShared.xcspec
+++ b/Sources/SWBApplePlatform/Specs/tvOSShared.xcspec
@@ -36,7 +36,7 @@
         _Domain = appletvos-shared;
         Type = Compiler;
         Identifier = "com.apple.compilers.assetcatalog";
-        BasedOn = "default:com.apple.compilers.assetcatalog";
+        BasedOn = "darwin:com.apple.compilers.assetcatalog";
         Options = (
             {
                 Name = "ASSETCATALOG_COMPILER_LEADERBOARD_IDENTIFIER_PREFIX";
diff --git a/Sources/SWBApplePlatform/Specs/watchOSShared.xcspec b/Sources/SWBApplePlatform/Specs/watchOSShared.xcspec
index c8205424..5fb16afc 100644
--- a/Sources/SWBApplePlatform/Specs/watchOSShared.xcspec
+++ b/Sources/SWBApplePlatform/Specs/watchOSShared.xcspec
@@ -122,7 +122,7 @@
         _Domain = watchos-shared;
         Type = Compiler;
         Identifier = "com.apple.compilers.assetcatalog";
-        BasedOn = "default:com.apple.compilers.assetcatalog";
+        BasedOn = "darwin:com.apple.compilers.assetcatalog";
         Options = (
             {
                 Name = "ASSETCATALOG_COMPILER_COMPLICATION_NAME";
diff --git a/Sources/SWBApplePlatform/Specs/xrOSShared.xcspec b/Sources/SWBApplePlatform/Specs/xrOSShared.xcspec
index a4bfaa9b..7dd579c9 100644
--- a/Sources/SWBApplePlatform/Specs/xrOSShared.xcspec
+++ b/Sources/SWBApplePlatform/Specs/xrOSShared.xcspec
@@ -15,7 +15,7 @@
         _Domain = xros-shared;
         Type = Compiler;
         Identifier = "com.apple.compilers.assetcatalog";
-        BasedOn = "default:com.apple.compilers.assetcatalog";
+        BasedOn = "darwin:com.apple.compilers.assetcatalog";
         Options = (
             {
                 Name = "ASSETCATALOG_COMPILER_FLATTENED_APP_ICON_PATH";
diff --git a/Sources/SWBCore/BuildRuleSet.swift b/Sources/SWBCore/BuildRuleSet.swift
index 65e2d518..a9aef7c2 100644
--- a/Sources/SWBCore/BuildRuleSet.swift
+++ b/Sources/SWBCore/BuildRuleSet.swift
@@ -166,7 +166,7 @@ extension Core {
         switch inputSpecifier {
         case let .fileType(fileTypeIdentifier):
             let domain = platform?.name ?? ""
-            condition = BuildRuleFileTypeCondition(fileType: try specRegistry.getSpec(fileTypeIdentifier, domain: domain) as FileTypeSpec)
+            condition = BuildRuleFileTypeCondition(fileType: try specRegistry.getSpec(fileTypeIdentifier, domain: domain, ofType: FileTypeSpec.self))
         case let .patterns(filePatterns):
             condition = BuildRuleFileNameCondition(namePatterns: filePatterns)
         }
@@ -181,13 +181,13 @@ extension Core {
 
         switch inputSpecifier {
         case let .fileType(fileTypeIdentifier):
-            let spec = try specRegistry.getSpec(compilerSpecificationIdentifier, domain: domain) as CommandLineToolSpec
+            let spec = try specRegistry.getSpec(compilerSpecificationIdentifier, domain: domain, ofType: CommandLineToolSpec.self)
 
             // Capture the tool spec's supports file types, if any.  But we only need to do this if the condition is not a pattern identifier.
             var toolSpecSupportedFileTypes = [FileTypeSpec]()
             if let inputFileTypeDescriptors = spec.inputFileTypeDescriptors {
                 for inputFileType in inputFileTypeDescriptors {
-                    let fileType = try specRegistry.getSpec(inputFileType.identifier, domain: domain) as FileTypeSpec
+                    let fileType = try specRegistry.getSpec(inputFileType.identifier, domain: domain, ofType: FileTypeSpec.self)
                     toolSpecSupportedFileTypes.append(fileType)
                 }
             }
@@ -195,7 +195,7 @@ extension Core {
             let action = BuildRuleTaskAction(toolSpec: spec)
 
             let condition: any BuildRuleCondition
-            let fileType = try specRegistry.getSpec(fileTypeIdentifier, domain: domain) as FileTypeSpec
+            let fileType = try specRegistry.getSpec(fileTypeIdentifier, domain: domain, ofType: FileTypeSpec.self)
             let fileTypes = toolSpecSupportedFileTypes.compactMap({ $0.conformsTo(fileType) ? $0 : nil })
             if fileTypes.isEmpty {
                 // If the compiler spec defined any supported file types, then the file types for the condition are those from the compiler spec which conform to the one we looked up.
@@ -208,7 +208,7 @@ extension Core {
             // Return the build rule condition and action.
             return (condition, action)
         case let .patterns(filePatterns):
-            return (BuildRuleFileNameCondition(namePatterns: filePatterns), BuildRuleTaskAction(toolSpec: try specRegistry.getSpec(compilerSpecificationIdentifier, domain: domain) as CommandLineToolSpec))
+            return (BuildRuleFileNameCondition(namePatterns: filePatterns), BuildRuleTaskAction(toolSpec: try specRegistry.getSpec(compilerSpecificationIdentifier, domain: domain, ofType: CommandLineToolSpec.self)))
         }
     }
 }
diff --git a/Sources/SWBCore/Core.swift b/Sources/SWBCore/Core.swift
index b01421d2..b26a9cd7 100644
--- a/Sources/SWBCore/Core.swift
+++ b/Sources/SWBCore/Core.swift
@@ -618,7 +618,7 @@ public final class Core: Sendable {
 
     public func productTypeSupportsMacCatalyst(productTypeIdentifier: String) throws -> Bool {
         do {
-            let productTypeSpec = try specRegistry.getSpec(productTypeIdentifier, domain: "macosx") as ProductTypeSpec
+            let productTypeSpec = try specRegistry.getSpec(productTypeIdentifier, domain: "macosx", ofType: ProductTypeSpec.self)
             return productTypeSupportsPlatform(productType: productTypeSpec, platformName: "macosx")
         } catch SpecLoadingError.notFound {
             return false
diff --git a/Sources/SWBCore/Settings/Settings.swift b/Sources/SWBCore/Settings/Settings.swift
index 4ab5f84d..1410b398 100644
--- a/Sources/SWBCore/Settings/Settings.swift
+++ b/Sources/SWBCore/Settings/Settings.swift
@@ -287,24 +287,16 @@ fileprivate struct PreOverridesSettings {
             // We’ll be building up and returning an array of condition-action pairs.
             var rules = [(any BuildRuleCondition, any BuildRuleAction)]()
 
-            guard let tiffutilToolSpec = specLookupContext.getSpec("com.apple.compilers.tiffutil") as? CommandLineToolSpec else {
-                diagnostics.append(Diagnostic(behavior: .error, location: .unknown, data: DiagnosticData("Couldn't load tool spec com.apple.compilers.tiffutil")))
-                return .init(rules: [], diagnostics: diagnostics)
-            }
-
-            guard let copyTiffFileToolSpec = specLookupContext.getSpec("com.apple.build-tasks.copy-tiff-file") as? CommandLineToolSpec else {
-                diagnostics.append(Diagnostic(behavior: .error, location: .unknown, data: DiagnosticData("Couldn't load tool spec com.apple.build-tasks.copy-tiff-file")))
-                return .init(rules: [], diagnostics: diagnostics)
-            }
-
-            // Temporary hack: Add a couple of rules for combining HiDPI images. These rules are handled through custom logic in the legacy build system. We emulate this by making them precede the other rules.
-            let tiffRuleAction = combineHiDPIImages ? tiffutilToolSpec : copyTiffFileToolSpec
-            // FIXME: This should probably use file types instead of patterns once we have a good API for that.
-            rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.tiff") }]), BuildRuleTaskAction(toolSpec: tiffRuleAction)))
-            rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.tif") }]), BuildRuleTaskAction(toolSpec: tiffRuleAction)))
-            if combineHiDPIImages {
-                rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.png") }]), BuildRuleTaskAction(toolSpec: tiffutilToolSpec)))
-                rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.jpg") }]), BuildRuleTaskAction(toolSpec: tiffutilToolSpec)))
+            if let tiffutilToolSpec = specLookupContext.getSpec("com.apple.compilers.tiffutil") as? CommandLineToolSpec, let copyTiffFileToolSpec = specLookupContext.getSpec("com.apple.build-tasks.copy-tiff-file") as? CommandLineToolSpec {
+                // Temporary hack: Add a couple of rules for combining HiDPI images. These rules are handled through custom logic in the legacy build system. We emulate this by making them precede the other rules.
+                let tiffRuleAction = combineHiDPIImages ? tiffutilToolSpec : copyTiffFileToolSpec
+                // FIXME: This should probably use file types instead of patterns once we have a good API for that.
+                rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.tiff") }]), BuildRuleTaskAction(toolSpec: tiffRuleAction)))
+                rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.tif") }]), BuildRuleTaskAction(toolSpec: tiffRuleAction)))
+                if combineHiDPIImages {
+                    rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.png") }]), BuildRuleTaskAction(toolSpec: tiffutilToolSpec)))
+                    rules.append((BuildRuleFileNameCondition(namePatterns: [Static { namespace.parseString("*.jpg") }]), BuildRuleTaskAction(toolSpec: tiffutilToolSpec)))
+                }
             }
 
             // First we synthesize build rules from tool specifications which declare that they do so.
@@ -1674,7 +1666,7 @@ private class SettingsBuilder: ProjectMatchLookup {
             self.warnings.append("Applying Swift Build settings override to project for \(projectOverrideSpec.bugReport).")
         }
 
-        if let swiftSpec = try? specLookupContext.getSpec() as SwiftCompilerSpec {
+        if let swiftSpec = try? specLookupContext.getSpec(ofType: SwiftCompilerSpec.self) {
             var swiftVersion = scope.evaluate(BuiltinMacros.SWIFT_VERSION)
             do {
                 let parsedSwiftVersion = try Version(swiftVersion)
@@ -5004,7 +4996,7 @@ private class SettingsBuilder: ProjectMatchLookup {
         ] {
             if let definedAtLevels = settingDefinedAtLevels(setting) {
                 for arch in scope.evaluate(BuiltinMacros.ARCHS) {
-                    if let archSpec: ArchitectureSpec = try? specLookupContext.getSpec(arch), !archSpec.supportsMergeableLibraries {
+                    if let archSpec = try? specLookupContext.getSpec(arch, ofType: ArchitectureSpec.self), !archSpec.supportsMergeableLibraries {
                         errors.append("Mergeable libraries are not supported for architecture '\(arch)', but \(setting.name) is assigned at level" + (definedAtLevels.count > 1 ? "s" : "") + ": " + definedAtLevels.joined(separator: ", ") + ".")
                     }
                 }
diff --git a/Sources/SWBCore/SpecImplementations/ProductTypes.swift b/Sources/SWBCore/SpecImplementations/ProductTypes.swift
index 3492c1de..bdc6f238 100644
--- a/Sources/SWBCore/SpecImplementations/ProductTypes.swift
+++ b/Sources/SWBCore/SpecImplementations/ProductTypes.swift
@@ -741,7 +741,7 @@ public final class XCTestBundleProductTypeSpec : BundleProductTypeSpec, @uncheck
         table.push(BuiltinMacros._BUILDABLE_SERIALIZATION_KEY, literal: "test-bundle-with-host: \(testHost)")
 
         // Inject a runpath search path to the host app's Frameworks directory if it isn't already present to ensure the embedded libraries can be found
-        let applicationProductType: ProductTypeSpec? = try? platform?.specRegistryProvider.specRegistry.getSpec("com.apple.product-type.application", domain: platform?.name ?? "")
+        let applicationProductType = try? platform?.specRegistryProvider.specRegistry.getSpec("com.apple.product-type.application", domain: platform?.name ?? "", ofType: ProductTypeSpec.self)
         if let frameworksRunpath = applicationProductType?.frameworksRunpathSearchPath(in: scope)?.str {
             if !scope.evaluate(BuiltinMacros.LD_RUNPATH_SEARCH_PATHS).contains(frameworksRunpath) {
                 table.push(BuiltinMacros.LD_RUNPATH_SEARCH_PATHS, BuiltinMacros.namespace.parseStringList(["$(inherited)", frameworksRunpath]))
diff --git a/Sources/SWBCore/SpecImplementations/SpecRegistry.swift b/Sources/SWBCore/SpecImplementations/SpecRegistry.swift
index b6e0164b..9dd120ae 100644
--- a/Sources/SWBCore/SpecImplementations/SpecRegistry.swift
+++ b/Sources/SWBCore/SpecImplementations/SpecRegistry.swift
@@ -886,7 +886,7 @@ public final class SpecRegistry: Sendable {
     }
 
     /// Get the loaded spec of a specific type for a given identifier and domain.  If no such spec exists or if it is not of the expected type, an error will be thrown.
-    public func getSpec<T: Spec>(_ identifier: String, domain: String = "") throws -> T {
+    public func getSpec<T: Spec>(_ identifier: String, domain: String = "", ofType _: T.Type) throws -> T {
         guard let spec = getSpec(identifier, domain: domain) else {
             throw SpecLoadingError.notFound(identifier: identifier, domain: domain)
         }
@@ -899,8 +899,8 @@ public final class SpecRegistry: Sendable {
     /// Get the loaded spec of a specific type for a given identifier and domain.  If no such spec exists or if it is not of the expected type, an error will be thrown.
     ///
     /// This is a convenience overload for identified spec types which removes the need to manually pass in the identifier.
-    public func getSpec<T: Spec & IdentifiedSpecType>(domain: String = "") throws -> T {
-        return try getSpec(T.identifier, domain: domain)
+    public func getSpec<T: Spec & IdentifiedSpecType>(domain: String = "", ofType type: T.Type) throws -> T {
+        return try getSpec(T.identifier, domain: domain, ofType: type)
     }
 
     /// Validate that there are no cases where a spec depends on one in a subdomain.  This is only used by `SpecLoadingTests.testSpecDomainInversion()`.
@@ -1094,15 +1094,15 @@ extension SpecLookupContext {
     }
 
     /// Get the loaded spec of a specific type for a given identifier and domain.  If no such spec exists or if it is not of the expected type, an error will be thrown.
-    public func getSpec<T: Spec>(_ identifier: String) throws -> T {
-        return try specRegistry.getSpec(identifier, domain: domain)
+    public func getSpec<T: Spec>(_ identifier: String, ofType type: T.Type) throws -> T {
+        return try specRegistry.getSpec(identifier, domain: domain, ofType: type)
     }
 
     /// Get the loaded spec of a specific type for a given identifier and domain.  If no such spec exists or if it is not of the expected type, an error will be thrown.
     ///
     /// This is a convenience overload for identified spec types which removes the need to manually pass in the identifier.
-    public func getSpec<T: Spec & IdentifiedSpecType>(domain: String = "") throws -> T {
-        return try getSpec(T.identifier)
+    public func getSpec<T: Spec & IdentifiedSpecType>(domain: String = "", ofType type: T.Type) throws -> T {
+        return try getSpec(T.identifier, ofType: type)
     }
 
     /// Looks up and returns the FileType (if any) that has the identifier `ident`.
diff --git a/Sources/SWBCore/SpecImplementations/Tools/ModulesVerifierTool.swift b/Sources/SWBCore/SpecImplementations/Tools/ModulesVerifierTool.swift
index a584628e..631aedfe 100644
--- a/Sources/SWBCore/SpecImplementations/Tools/ModulesVerifierTool.swift
+++ b/Sources/SWBCore/SpecImplementations/Tools/ModulesVerifierTool.swift
@@ -23,7 +23,7 @@ public final class ModulesVerifierToolSpec : GenericCommandLineToolSpec, SpecIde
     public func constructModuleVerifierTasks(_ cbc: CommandBuildContext, _ delegate: any TaskGenerationDelegate, alwaysExecuteTask: Bool, fileNameMapPath: Path) async {
         let ruleInfo = defaultRuleInfo(cbc, delegate)
 
-        let clangSpec = try! cbc.producer.getSpec() as ClangCompilerSpec
+        let clangSpec = try! cbc.producer.getSpec(ofType: ClangCompilerSpec.self)
         let clangPath = await clangSpec.resolveExecutablePath(cbc, Path("clang"), delegate: delegate)
         let specialArguments = ["--clang", clangPath.str, "--diagnostic-filename-map", fileNameMapPath.str]
 
diff --git a/Sources/SWBCore/TaskGeneration.swift b/Sources/SWBCore/TaskGeneration.swift
index af1347e8..95df409b 100644
--- a/Sources/SWBCore/TaskGeneration.swift
+++ b/Sources/SWBCore/TaskGeneration.swift
@@ -174,10 +174,10 @@ public protocol CommandProducer: PlatformBuildContext, SpecLookupContext, Refere
     var copySpec: CopyToolSpec { get }
 
     /// The copy-png spec to use.
-    var copyPngSpec: CommandLineToolSpec { get }
+    var copyPngSpec: CommandLineToolSpec? { get }
 
     /// The copy-tiff spec to use.
-    var copyTiffSpec: CommandLineToolSpec { get }
+    var copyTiffSpec: CommandLineToolSpec? { get }
 
     /// The unifdef spec to use.
     var unifdefSpec: UnifdefToolSpec { get }
diff --git a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/CopyFilesTaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/CopyFilesTaskProducer.swift
index 3daa8d31..bc3c7ecd 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/CopyFilesTaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/CopyFilesTaskProducer.swift
@@ -48,7 +48,7 @@ class CopyFilesTaskProducer: FilesBasedBuildPhaseTaskProducerBase, FilesBasedBui
 
         func lookupProductType(_ ident: String) -> ProductTypeSpec? {
             do {
-                return try context.getSpec(ident)
+                return try context.getSpec(ident, ofType: ProductTypeSpec.self)
             } catch {
                 context.error("Couldn't look up product type '\(ident)' in domain '\(context.domain)': \(error)")
                 return nil
@@ -498,7 +498,7 @@ class CopyFilesTaskProducer: FilesBasedBuildPhaseTaskProducerBase, FilesBasedBui
                 }
 
                 if !scope.evaluate(BuiltinMacros.BUILD_COMPONENTS).contains("installLoc") {
-                    await context.validateEmbeddedBinarySpec.constructValidateEmbeddedBinaryTask(cbc, delegate, lookup: lookup)
+                    await context.validateEmbeddedBinarySpec?.constructValidateEmbeddedBinaryTask(cbc, delegate, lookup: lookup)
                 }
             }
         }
diff --git a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/FilesBasedBuildPhaseTaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/FilesBasedBuildPhaseTaskProducer.swift
index 37612eb5..d4acb6d9 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/FilesBasedBuildPhaseTaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/FilesBasedBuildPhaseTaskProducer.swift
@@ -689,7 +689,7 @@ package class FilesBasedBuildPhaseTaskProducerBase: PhasedTaskProducer {
                 if !scope.evaluate(BuiltinMacros.SUPPORTS_TEXT_BASED_API) {
                     // If TAPI support errors are disabled or this task type doesn't actually require it, ignore the error.
                     if !scope.evaluate(BuiltinMacros.ALLOW_UNSUPPORTED_TEXT_BASED_API) && group.assignedBuildRuleAction?.requiresTextBasedAPI ?? false {
-                        let productType: ProductTypeSpec? = try? context.getSpec(scope.evaluate(BuiltinMacros.PRODUCT_TYPE))
+                        let productType = try? context.getSpec(scope.evaluate(BuiltinMacros.PRODUCT_TYPE), ofType: ProductTypeSpec.self)
                         if let productType = productType, productType.supportsInstallAPI && !generatedRequiresAPIError {
                             producer.context.error("\(productType.name) requested to generate API, but has not adopted SUPPORTS_TEXT_BASED_API", location: .buildSetting(BuiltinMacros.SUPPORTS_TEXT_BASED_API))
                             generatedRequiresAPIError = true
diff --git a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/SwiftPackageCopyFilesTaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/SwiftPackageCopyFilesTaskProducer.swift
index 814cb269..7a70bd17 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/SwiftPackageCopyFilesTaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/SwiftPackageCopyFilesTaskProducer.swift
@@ -26,7 +26,7 @@ final class SwiftPackageCopyFilesTaskProducer: CopyFilesTaskProducer {
 
         func lookupProductType(_ ident: String) -> ProductTypeSpec? {
             do {
-                return try context.getSpec(ident)
+                return try context.getSpec(ident, ofType: ProductTypeSpec.self)
             } catch {
                 context.error("Couldn't look up product type '\(ident)' in domain '\(context.domain)': \(error)")
                 return nil
diff --git a/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/CopySwiftPackageResourcesTaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/CopySwiftPackageResourcesTaskProducer.swift
index 1a7938e7..06e630e5 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/CopySwiftPackageResourcesTaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/CopySwiftPackageResourcesTaskProducer.swift
@@ -39,7 +39,7 @@ final class CopySwiftPackageResourcesTaskProducer: PhasedTaskProducer, TaskProdu
         let productTypeIdentifier = scope.evaluate(BuiltinMacros.PRODUCT_TYPE)
         func lookupProductType(_ ident: String) -> ProductTypeSpec? {
             do {
-                return try context.getSpec(ident)
+                return try context.getSpec(ident, ofType: ProductTypeSpec.self)
             } catch {
                 context.error("Couldn't look up product type '\(ident)' in domain '\(context.domain)': \(error)")
                 return nil
diff --git a/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/ProductPostprocessingTaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/ProductPostprocessingTaskProducer.swift
index 8fbddd3c..7ab88f14 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/ProductPostprocessingTaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/OtherTaskProducers/ProductPostprocessingTaskProducer.swift
@@ -541,12 +541,12 @@ final class ProductPostprocessingTaskProducer: PhasedTaskProducer, TaskProducer
         // If the product type specifies a validation tool to run, then we create a task to do so.
         // Presently we only create this task for iOS/tvOS/watchOS/macOS device application products.
         // FIXME: The fact that the product type spec defines the identifier of the tool to use is wacky, since nothing is taking advantage of it, so we take advantage of that by just doing the simple thing to get the one tool spec we know about.
-        if let identifier = context.productType?.productValidationToolSpecIdentifier, identifier == context.validateProductSpec.identifier {
+        if let validateProductSpec = context.validateProductSpec, let identifier = context.productType?.productValidationToolSpecIdentifier, identifier == validateProductSpec.identifier {
             await appendGeneratedTasks(&tasks) { delegate in
                 let input = FileToBuild(context: context, absolutePath: scope.evaluate(BuiltinMacros.TARGET_BUILD_DIR).join(scope.evaluate(BuiltinMacros.FULL_PRODUCT_NAME)).normalize())
                 let additionalInputs = hostedProductPaths.map({ context.createDirectoryTreeNode($0, excluding: []) })
                 let cbc = CommandBuildContext(producer: context, scope: scope, inputs: [input], commandOrderingInputs: additionalInputs, commandOrderingOutputs: [delegate.createVirtualNode("Validate \(input.absolutePath.str)")])
-                await context.validateProductSpec.constructTasks(cbc, delegate)
+                await validateProductSpec.constructTasks(cbc, delegate)
             }
         }
     }
@@ -648,13 +648,14 @@ private extension ApplicationProductTypeSpec {
         // If we're building for the macOS platform, then register the application with LaunchServices.  c.f. <rdar://problem/18464352> Handoff doesn't work with app launched from Xcode
         let context = producer.context
         guard context.settings.platform?.name == "macosx" else { return }
+        guard let launchServicesRegisterSpec = context.launchServicesRegisterSpec else { return }
 
         let path = scope.evaluate(BuiltinMacros.TARGET_BUILD_DIR).join(scope.evaluate(BuiltinMacros.WRAPPER_NAME))
         await producer.appendGeneratedTasks(&tasks) { delegate in
             // Mutating tasks *require* the input node, otherwise this task will not properly run for incremental builds.
             let vnode = delegate.createVirtualNode("LSRegisterURL \(path.str)")
 
-            await context.launchServicesRegisterSpec.constructTasks(CommandBuildContext(producer: context, scope: scope, inputs: [FileToBuild(context: context, absolutePath: path)], output: path, commandOrderingOutputs: [vnode]), delegate)
+            await launchServicesRegisterSpec.constructTasks(CommandBuildContext(producer: context, scope: scope, inputs: [FileToBuild(context: context, absolutePath: path)], output: path, commandOrderingOutputs: [vnode]), delegate)
         }
     }
 }
diff --git a/Sources/SWBTaskConstruction/TaskProducers/TaskProducer.swift b/Sources/SWBTaskConstruction/TaskProducers/TaskProducer.swift
index 115a5396..a716cca2 100644
--- a/Sources/SWBTaskConstruction/TaskProducers/TaskProducer.swift
+++ b/Sources/SWBTaskConstruction/TaskProducers/TaskProducer.swift
@@ -218,8 +218,8 @@ public class TaskProducerContext: StaleFileRemovalContext, BuildFileResolution
         }
     }
 
-    public let appShortcutStringsMetadataCompilerSpec: AppShortcutStringsMetadataCompilerSpec
-    let appleScriptCompilerSpec: CommandLineToolSpec
+    public let appShortcutStringsMetadataCompilerSpec: AppShortcutStringsMetadataCompilerSpec?
+    let appleScriptCompilerSpec: CommandLineToolSpec?
     let buildDependencyInfoSpec: BuildDependencyInfoSpec
     public let clangSpec: ClangCompilerSpec
     public let clangAssemblerSpec: ClangCompilerSpec
@@ -233,8 +233,8 @@ public class TaskProducerContext: StaleFileRemovalContext, BuildFileResolution
     var concatenateSpec: ConcatenateToolSpec? { return specForResult(_concatenateSpec) }
     public let copySpec: CopyToolSpec
     let copyPlistSpec: CommandLineToolSpec
-    public let copyPngSpec: CommandLineToolSpec
-    public let copyTiffSpec: CommandLineToolSpec
+    public let copyPngSpec: CommandLineToolSpec?
+    public let copyTiffSpec: CommandLineToolSpec?
     let cppSpec: CommandLineToolSpec
     let createAssetPackManifestSpec: CreateAssetPackManifestToolSpec
     public let createBuildDirectorySpec: CreateBuildDirectorySpec
@@ -242,7 +242,7 @@ public class TaskProducerContext: StaleFileRemovalContext, BuildFileResolution
     let dsymutilSpec: DsymutilToolSpec
     let infoPlistSpec: InfoPlistToolSpec
     let mergeInfoPlistSpec: MergeInfoPlistSpec
-    let launchServicesRegisterSpec: CommandLineToolSpec
+    let launchServicesRegisterSpec: CommandLineToolSpec?
     public let ldLinkerSpec: LdLinkerSpec
     public let libtoolLinkerSpec: LibtoolLinkerSpec
     public let lipoSpec: LipoToolSpec
@@ -270,8 +270,8 @@ public class TaskProducerContext: StaleFileRemovalContext, BuildFileResolution
     let tapiStubifySpec: CommandLineToolSpec
     let touchSpec: CommandLineToolSpec
     public let unifdefSpec: UnifdefToolSpec
-    let validateEmbeddedBinarySpec: ValidateEmbeddedBinaryToolSpec
-    let validateProductSpec: ValidateProductToolSpec
+    let validateEmbeddedBinarySpec: ValidateEmbeddedBinaryToolSpec?
+    let validateProductSpec: ValidateProductToolSpec?
     let processXCFrameworkLibrarySpec: ProcessXCFrameworkLibrarySpec
     public let processSDKImportsSpec: ProcessSDKImportsSpec
     public let validateDependenciesSpec: ValidateDependenciesSpec
@@ -343,65 +343,65 @@ public class TaskProducerContext: StaleFileRemovalContext, BuildFileResolution
         //
         // FIXME: These should really be bound even earlier, like in the spec cache. Or at least, we should throw here and just produce a dep graph error if any are missing.
         let domain = settings.platform?.name ?? ""
-        self.appShortcutStringsMetadataCompilerSpec = workspaceContext.core.specRegistry.getSpec("com.apple.compilers.appshortcutstringsmetadata", domain: domain) as! AppShortcutStringsMetadataCompilerSpec
-        self.appleScriptCompilerSpec = workspaceContext.core.specRegistry.getSpec("com.apple.compilers.osacompile", domain: domain) as! CommandLineToolSpec
+        self.appShortcutStringsMetadataCompilerSpec = workspaceContext.core.specRegistry.getSpec("com.apple.compilers.appshortcutstringsmetadata", domain: domain) as? AppShortcutStringsMetadataCompilerSpec
+        self.appleScriptCompilerSpec = workspaceContext.core.specRegistry.getSpec("com.apple.compilers.osacompile", domain: domain) as? CommandLineToolSpec
         self.buildDependencyInfoSpec = workspaceContext.core.specRegistry.getSpec(BuildDependencyInfoSpec.identifier, domain: domain) as! BuildDependencyInfoSpec
-        self.clangSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ClangCompilerSpec
-        self.clangAssemblerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ClangAssemblerSpec
-        self.clangPreprocessorSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ClangPreprocessorSpec
-        self.clangStaticAnalyzerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ClangStaticAnalyzerSpec
-        self.clangModuleVerifierSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ClangModuleVerifierSpec
-        self._clangStatCacheSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.clang-stat-cache") as ClangStatCacheSpec }
-        self.codesignSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.codesign", domain: domain) as! CodesignToolSpec
-        self._concatenateSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.concatenate") as ConcatenateToolSpec }
-        self.copySpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as CopyToolSpec
-        self.copyPlistSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-plist-file", domain: domain) as! CommandLineToolSpec
-        self.copyPngSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-png-file", domain: domain) as! CommandLineToolSpec
-        self.copyTiffSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-tiff-file", domain: domain) as! CommandLineToolSpec
-        self.cppSpec = workspaceContext.core.specRegistry.getSpec("com.apple.compilers.cpp", domain: domain) as! CommandLineToolSpec
-        self.createAssetPackManifestSpec = workspaceContext.core.specRegistry.getSpec(CreateAssetPackManifestToolSpec.identifier, domain: domain) as! CreateAssetPackManifestToolSpec
-        self.createBuildDirectorySpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.create-build-directory", domain: domain) as! CreateBuildDirectorySpec
-        self.diffSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.diff", domain: domain) as! CommandLineToolSpec
-        self.dsymutilSpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.dsymutil", domain: domain) as! DsymutilToolSpec
-        self.infoPlistSpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.info-plist-utility", domain: domain) as! InfoPlistToolSpec
-        self.mergeInfoPlistSpec = workspaceContext.core.specRegistry.getSpec(MergeInfoPlistSpec.identifier, domain: domain) as! MergeInfoPlistSpec
-        self.launchServicesRegisterSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.ls-register-url", domain: domain) as! CommandLineToolSpec
-        self.ldLinkerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as LdLinkerSpec
-        self.libtoolLinkerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as LibtoolLinkerSpec
-        self.lipoSpec = workspaceContext.core.specRegistry.getSpec("com.apple.xcode.linkers.lipo", domain: domain) as! LipoToolSpec
-        self.prelinkedObjectLinkSpec = workspaceContext.core.specRegistry.getSpec(PrelinkedObjectLinkSpec.identifier, domain: domain) as! CommandLineToolSpec
-        self.mkdirSpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.mkdir", domain: domain) as! MkdirToolSpec
-        self.modulesVerifierSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.modules-verifier", domain: domain) as! ModulesVerifierToolSpec
-        self.clangModuleVerifierInputGeneratorSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.module-verifier-input-generator", domain: domain) as! ClangModuleVerifierInputGeneratorSpec
-        self.productPackagingSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as ProductPackagingToolSpec
+        self.clangSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ClangCompilerSpec.self)
+        self.clangAssemblerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ClangAssemblerSpec.self)
+        self.clangPreprocessorSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ClangPreprocessorSpec.self)
+        self.clangStaticAnalyzerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ClangStaticAnalyzerSpec.self)
+        self.clangModuleVerifierSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ClangModuleVerifierSpec.self)
+        self._clangStatCacheSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.clang-stat-cache", ofType: ClangStatCacheSpec.self) }
+        self.codesignSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.codesign", domain: domain, ofType: CodesignToolSpec.self)
+        self._concatenateSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.concatenate", ofType: ConcatenateToolSpec.self) }
+        self.copySpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: CopyToolSpec.self)
+        self.copyPlistSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-plist-file", domain: domain, ofType: CommandLineToolSpec.self)
+        self.copyPngSpec = try? workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-png-file", domain: domain, ofType: CommandLineToolSpec.self)
+        self.copyTiffSpec = try? workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.copy-tiff-file", domain: domain, ofType: CommandLineToolSpec.self)
+        self.cppSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.compilers.cpp", domain: domain, ofType: CommandLineToolSpec.self)
+        self.createAssetPackManifestSpec = try! workspaceContext.core.specRegistry.getSpec(CreateAssetPackManifestToolSpec.identifier, domain: domain, ofType: CreateAssetPackManifestToolSpec.self)
+        self.createBuildDirectorySpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.create-build-directory", domain: domain, ofType: CreateBuildDirectorySpec.self)
+        self.diffSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.diff", domain: domain, ofType: CommandLineToolSpec.self)
+        self.dsymutilSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.dsymutil", domain: domain, ofType: DsymutilToolSpec.self)
+        self.infoPlistSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.info-plist-utility", domain: domain, ofType: InfoPlistToolSpec.self)
+        self.mergeInfoPlistSpec = try! workspaceContext.core.specRegistry.getSpec(MergeInfoPlistSpec.identifier, domain: domain, ofType: MergeInfoPlistSpec.self)
+        self.launchServicesRegisterSpec = try? workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.ls-register-url", domain: domain, ofType: CommandLineToolSpec.self)
+        self.ldLinkerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: LdLinkerSpec.self)
+        self.libtoolLinkerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: LibtoolLinkerSpec.self)
+        self.lipoSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.xcode.linkers.lipo", domain: domain, ofType: LipoToolSpec.self)
+        self.prelinkedObjectLinkSpec = try! workspaceContext.core.specRegistry.getSpec(PrelinkedObjectLinkSpec.identifier, domain: domain, ofType: CommandLineToolSpec.self)
+        self.mkdirSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.mkdir", domain: domain, ofType: MkdirToolSpec.self)
+        self.modulesVerifierSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.modules-verifier", domain: domain, ofType: ModulesVerifierToolSpec.self)
+        self.clangModuleVerifierInputGeneratorSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.module-verifier-input-generator", domain: domain, ofType: ClangModuleVerifierInputGeneratorSpec.self)
+        self.productPackagingSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: ProductPackagingToolSpec.self)
         self._registerExecutionPolicyExceptionSpec = .init(workspaceContext, settings)
-        self.setAttributesSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.set-attributes", domain: domain) as! SetAttributesSpec
-        self.shellScriptSpec = workspaceContext.core.specRegistry.getSpec("com.apple.commands.shell-script", domain: domain) as! ShellScriptToolSpec
-        self.signatureCollectionSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.signature-collection", domain: domain) as! SignatureCollectionSpec
+        self.setAttributesSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.set-attributes", domain: domain, ofType: SetAttributesSpec.self)
+        self.shellScriptSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.commands.shell-script", domain: domain, ofType: ShellScriptToolSpec.self)
+        self.signatureCollectionSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.signature-collection", domain: domain, ofType: SignatureCollectionSpec.self)
         self.stripSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.strip", domain: domain) as! StripToolSpec
-        self.swiftCompilerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain) as SwiftCompilerSpec
-        self.swiftHeaderToolSpec = workspaceContext.core.specRegistry.getSpec(SwiftHeaderToolSpec.identifier, domain: domain) as! SwiftHeaderToolSpec
-        self.swiftStdlibToolSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-stdlib-tool", domain: domain) as! SwiftStdLibToolSpec
-        self._swiftABICheckerToolSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-abi-checker", domain: domain) as SwiftABICheckerToolSpec }
-        self._swiftABIGenerationToolSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-abi-generation", domain: domain) as SwiftABIGenerationToolSpec }
-        self.symlinkSpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.symlink", domain: domain) as! SymlinkToolSpec
-        self.tapiSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.installapi", domain: domain) as! TAPIToolSpec
-        self.tapiMergeSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.merge", domain: domain) as! CommandLineToolSpec
-        self.tapiStubifySpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.stubify", domain: domain) as! CommandLineToolSpec
-        self.touchSpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.touch", domain: domain) as! CommandLineToolSpec
-        self.unifdefSpec = workspaceContext.core.specRegistry.getSpec("public.build-task.unifdef", domain: domain) as! UnifdefToolSpec
-        self.validateEmbeddedBinarySpec = workspaceContext.core.specRegistry.getSpec("com.apple.tools.validate-embedded-binary-utility", domain: domain) as! ValidateEmbeddedBinaryToolSpec
-        self.validateProductSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.platform.validate", domain: domain) as! ValidateProductToolSpec
-        self.processXCFrameworkLibrarySpec = workspaceContext.core.specRegistry.getSpec(ProcessXCFrameworkLibrarySpec.identifier, domain: domain) as! ProcessXCFrameworkLibrarySpec
-        self.processSDKImportsSpec = workspaceContext.core.specRegistry.getSpec(ProcessSDKImportsSpec.identifier, domain: domain) as! ProcessSDKImportsSpec
-        self.validateDependenciesSpec = workspaceContext.core.specRegistry.getSpec(ValidateDependenciesSpec.identifier, domain: domain) as! ValidateDependenciesSpec
-        self.writeFileSpec = workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.write-file", domain: domain) as! WriteFileSpec
-        self._documentationCompilerSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation", domain: domain) as CommandLineToolSpec }
-        self._tapiSymbolExtractorSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation.objc-symbol-extract", domain: domain) as TAPISymbolExtractor }
-        self._swiftSymbolExtractorSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation.swift-symbol-extract", domain: domain) as CommandLineToolSpec }
-        self._developmentAssetsSpec = Result { try workspaceContext.core.specRegistry.getSpec(ValidateDevelopmentAssets.identifier, domain: domain) as CommandLineToolSpec }
-        self._generateAppPlaygroundAssetCatalogSpec = Result { try workspaceContext.core.specRegistry.getSpec(GenerateAppPlaygroundAssetCatalog.identifier, domain: domain) as CommandLineToolSpec }
-        self._realityAssetsCompilerSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.compile-rk-assets.xcplugin", domain: domain) as CommandLineToolSpec }
+        self.swiftCompilerSpec = try! workspaceContext.core.specRegistry.getSpec(domain: domain, ofType: SwiftCompilerSpec.self)
+        self.swiftHeaderToolSpec = try! workspaceContext.core.specRegistry.getSpec(SwiftHeaderToolSpec.identifier, domain: domain, ofType: SwiftHeaderToolSpec.self)
+        self.swiftStdlibToolSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-stdlib-tool", domain: domain, ofType: SwiftStdLibToolSpec.self)
+        self._swiftABICheckerToolSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-abi-checker", domain: domain, ofType: SwiftABICheckerToolSpec.self) }
+        self._swiftABIGenerationToolSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.swift-abi-generation", domain: domain, ofType: SwiftABIGenerationToolSpec.self) }
+        self.symlinkSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.symlink", domain: domain, ofType: SymlinkToolSpec.self)
+        self.tapiSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.installapi", domain: domain, ofType: TAPIToolSpec.self)
+        self.tapiMergeSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.merge", domain: domain, ofType: CommandLineToolSpec.self)
+        self.tapiStubifySpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.tapi.stubify", domain: domain, ofType: CommandLineToolSpec.self)
+        self.touchSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.tools.touch", domain: domain, ofType: CommandLineToolSpec.self)
+        self.unifdefSpec = try! workspaceContext.core.specRegistry.getSpec("public.build-task.unifdef", domain: domain, ofType: UnifdefToolSpec.self)
+        self.validateEmbeddedBinarySpec = try? workspaceContext.core.specRegistry.getSpec("com.apple.tools.validate-embedded-binary-utility", domain: domain, ofType: ValidateEmbeddedBinaryToolSpec.self)
+        self.validateProductSpec = try? workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.platform.validate", domain: domain, ofType: ValidateProductToolSpec.self)
+        self.processXCFrameworkLibrarySpec = try! workspaceContext.core.specRegistry.getSpec(ProcessXCFrameworkLibrarySpec.identifier, domain: domain, ofType: ProcessXCFrameworkLibrarySpec.self)
+        self.processSDKImportsSpec = try! workspaceContext.core.specRegistry.getSpec(ProcessSDKImportsSpec.identifier, domain: domain, ofType: ProcessSDKImportsSpec.self)
+        self.validateDependenciesSpec = try! workspaceContext.core.specRegistry.getSpec(ValidateDependenciesSpec.identifier, domain: domain, ofType: ValidateDependenciesSpec.self)
+        self.writeFileSpec = try! workspaceContext.core.specRegistry.getSpec("com.apple.build-tools.write-file", domain: domain, ofType: WriteFileSpec.self)
+        self._documentationCompilerSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation", domain: domain, ofType: CommandLineToolSpec.self) }
+        self._tapiSymbolExtractorSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation.objc-symbol-extract", domain: domain, ofType: TAPISymbolExtractor.self) }
+        self._swiftSymbolExtractorSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.compilers.documentation.swift-symbol-extract", domain: domain, ofType: CommandLineToolSpec.self) }
+        self._developmentAssetsSpec = Result { try workspaceContext.core.specRegistry.getSpec(ValidateDevelopmentAssets.identifier, domain: domain, ofType: CommandLineToolSpec.self) }
+        self._generateAppPlaygroundAssetCatalogSpec = Result { try workspaceContext.core.specRegistry.getSpec(GenerateAppPlaygroundAssetCatalog.identifier, domain: domain, ofType: CommandLineToolSpec.self) }
+        self._realityAssetsCompilerSpec = Result { try workspaceContext.core.specRegistry.getSpec("com.apple.build-tasks.compile-rk-assets.xcplugin", domain: domain, ofType: CommandLineToolSpec.self) }
 
         self.compilationRequirementOutputFileTypes = (SpecRegistry.headerFileTypeIdentifiers + [SpecRegistry.modulemapFileTypeIdentifier]).compactMap { workspaceContext.core.specRegistry.lookupFileType(identifier: $0, domain: domain) }
         self.emitFrontendCommandLines = settings.globalScope.evaluate(BuiltinMacros.EMIT_FRONTEND_COMMAND_LINES)
@@ -1333,7 +1333,7 @@ extension TaskProducerContext: CommandProducer {
             // arch is a VALID_ARCHS of the dependency but it's not building for that arch, we need to find a compatible one
             let dependencyArchs = dependencyScope.evaluate(BuiltinMacros.ARCHS)
             if false == dependencyArchs.contains(arch) {
-                guard let archSpec: ArchitectureSpec = try? workspaceContext.core.specRegistry.getSpec(arch) else {
+                guard let archSpec = try? workspaceContext.core.specRegistry.getSpec(arch, ofType: ArchitectureSpec.self) else {
                     return nil
                 }
                 // Currently there is no more than one compatibility arch; first might not be correct otherwise
@@ -1755,6 +1755,6 @@ class PhasedProducerBasedTaskGenerationDelegate: ProducerBasedTaskGenerationDele
 
 fileprivate extension Result where Success: Spec & IdentifiedSpecType, Failure == any Error {
     init(_ workspaceContext: WorkspaceContext, _ settings: Settings) {
-        self = Result { try workspaceContext.core.specRegistry.getSpec(domain: settings.platform?.name ?? "") }
+        self = Result { try workspaceContext.core.specRegistry.getSpec(domain: settings.platform?.name ?? "", ofType: Success.self) }
     }
 }
diff --git a/Sources/SWBTestSupport/CommandLineToolSpecDiscoveredInfo.swift b/Sources/SWBTestSupport/CommandLineToolSpecDiscoveredInfo.swift
index b35fb1d3..6c3a77eb 100644
--- a/Sources/SWBTestSupport/CommandLineToolSpecDiscoveredInfo.swift
+++ b/Sources/SWBTestSupport/CommandLineToolSpecDiscoveredInfo.swift
@@ -23,7 +23,7 @@ extension CoreBasedTests {
 
     package func withSpec<T: DiscoveredCommandLineToolSpecInfo>(_ identifier: String, _ result: ExternalToolResult, platform: String? = nil, additionalTable: MacroValueAssignmentTable? = nil, _ block: (_ info: T) throws -> Void, sourceLocation: SourceLocation = #_sourceLocation) async throws {
         let core = try await getCore()
-        let spec = try core.specRegistry.getSpec(identifier) as CommandLineToolSpec
+        let spec = try core.specRegistry.getSpec(identifier, domain: platform ?? "", ofType: CommandLineToolSpec.self)
 
         // Create the context to use to discover the info.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
diff --git a/Sources/SWBTestSupport/CoreBasedTests.swift b/Sources/SWBTestSupport/CoreBasedTests.swift
index 67255a67..6beda66f 100644
--- a/Sources/SWBTestSupport/CoreBasedTests.swift
+++ b/Sources/SWBTestSupport/CoreBasedTests.swift
@@ -89,7 +89,7 @@ extension CoreBasedTests {
             // FIXME: We could probably collapse all of this logic into a single method inside the spec, with some refactoring in several places.
             let swiftSpecInfo = try await discoveredSwiftCompilerInfo(at: swiftc)
             let provisionalSwiftVersion = swiftSpecInfo.swiftVersion
-            let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
+            let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
             let swiftVersion: Version
             switch swiftSpec.validateSwiftVersion(provisionalSwiftVersion) {
             case .invalid:
@@ -409,7 +409,7 @@ extension CoreBasedTests {
 
     fileprivate func discoveredToolSpecInfo(specIdentifier: String, sourceLocation: SourceLocation = #_sourceLocation) async throws -> (any DiscoveredCommandLineToolSpecInfo)? {
         let core = try await getCore()
-        let spec = try core.specRegistry.getSpec(specIdentifier) as CommandLineToolSpec
+        let spec = try core.specRegistry.getSpec(specIdentifier, ofType: CommandLineToolSpec.self)
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: nil, useStandardExecutableSearchPaths: true, toolchain: nil, fs: localFS)
         let delegate = DiscoveredInfoDelegate()
         let info = await spec.discoveredCommandLineToolSpecInfo(producer, MacroEvaluationScope(table: MacroValueAssignmentTable(namespace: MacroNamespace())), delegate)
diff --git a/Sources/SWBTestSupport/DummyCommandProducer.swift b/Sources/SWBTestSupport/DummyCommandProducer.swift
index def5fdee..b9148012 100644
--- a/Sources/SWBTestSupport/DummyCommandProducer.swift
+++ b/Sources/SWBTestSupport/DummyCommandProducer.swift
@@ -42,7 +42,7 @@ package struct MockCommandProducer: CommandProducer, Sendable {
         self.platform = platform
         self.sdk = (platform?.sdkCanonicalName).map(core.sdkRegistry.lookup) ?? nil
         self.sdkVariant = self.sdk?.defaultVariant
-        self.productType = try core.specRegistry.getSpec(productTypeIdentifier, domain: platform?.name ?? "") as ProductTypeSpec
+        self.productType = try core.specRegistry.getSpec(productTypeIdentifier, domain: platform?.name ?? "", ofType: ProductTypeSpec.self)
 
         // Construct some executable search paths if instructed, by mimicking part of what Settings.createExecutableSearchPaths() does, specifically:
         //  - Add from __XCODE_BUILT_PRODUCTS_DIR_PATHS, if present.
@@ -76,35 +76,35 @@ package struct MockCommandProducer: CommandProducer, Sendable {
         self.toolchains = toolchain.map { [$0] } ?? []
 
         // Work around compiler (can't use self.getSpec before self initialization)
-        func getSpec<T: Spec>(_ identifier: String) throws -> T {
-            try core.specRegistry.getSpec(identifier, domain: platform?.name ?? "")
+        func getSpec<T: Spec>(_ identifier: String, ofType type: T.Type) throws -> T {
+            try core.specRegistry.getSpec(identifier, domain: platform?.name ?? "", ofType: type)
         }
 
-        func getSpec<T: Spec & IdentifiedSpecType>() throws -> T {
-            try getSpec(T.identifier)
+        func getSpec<T: Spec & IdentifiedSpecType>(ofType type: T.Type) throws -> T {
+            try getSpec(T.identifier, ofType: type)
         }
 
-        self.clangSpec = try getSpec() as ClangCompilerSpec
-        self.clangAssemblerSpec = try getSpec() as ClangAssemblerSpec
-        self.clangPreprocessorSpec = try getSpec() as ClangPreprocessorSpec
-        self.clangStaticAnalyzerSpec = try getSpec() as ClangStaticAnalyzerSpec
-        self.clangModuleVerifierSpec = try getSpec() as ClangModuleVerifierSpec
-        self.diffSpec = try getSpec("com.apple.build-tools.diff") as CommandLineToolSpec
-        self.stripSpec = try getSpec("com.apple.build-tools.strip") as StripToolSpec
-        self.ldLinkerSpec = try getSpec() as LdLinkerSpec
-        self.libtoolLinkerSpec = try getSpec() as LibtoolLinkerSpec
-        self.lipoSpec = try getSpec() as LipoToolSpec
-        self.codesignSpec = try getSpec("com.apple.build-tools.codesign") as CodesignToolSpec
-        self.copySpec = try getSpec() as CopyToolSpec
-        self.copyPngSpec = try getSpec("com.apple.build-tasks.copy-png-file") as CommandLineToolSpec
-        self.copyTiffSpec = try getSpec("com.apple.build-tasks.copy-tiff-file") as CommandLineToolSpec
-        self.writeFileSpec = try getSpec("com.apple.build-tools.write-file") as WriteFileSpec
-        self.createBuildDirectorySpec = try getSpec("com.apple.tools.create-build-directory") as CreateBuildDirectorySpec
-        self.unifdefSpec = try getSpec("public.build-task.unifdef") as UnifdefToolSpec
-        self.mkdirSpec = try getSpec("com.apple.tools.mkdir") as MkdirToolSpec
-        self.swiftCompilerSpec = try getSpec() as SwiftCompilerSpec
-        self.processSDKImportsSpec = try getSpec(ProcessSDKImportsSpec.identifier) as ProcessSDKImportsSpec
-        self.validateDependenciesSpec = try getSpec(ValidateDependenciesSpec.identifier) as ValidateDependenciesSpec
+        self.clangSpec = try getSpec(ofType: ClangCompilerSpec.self)
+        self.clangAssemblerSpec = try getSpec(ofType: ClangAssemblerSpec.self)
+        self.clangPreprocessorSpec = try getSpec(ofType: ClangPreprocessorSpec.self)
+        self.clangStaticAnalyzerSpec = try getSpec(ofType: ClangStaticAnalyzerSpec.self)
+        self.clangModuleVerifierSpec = try getSpec(ofType: ClangModuleVerifierSpec.self)
+        self.diffSpec = try getSpec("com.apple.build-tools.diff", ofType: CommandLineToolSpec.self)
+        self.stripSpec = try getSpec("com.apple.build-tools.strip", ofType: StripToolSpec.self)
+        self.ldLinkerSpec = try getSpec(ofType: LdLinkerSpec.self)
+        self.libtoolLinkerSpec = try getSpec(ofType: LibtoolLinkerSpec.self)
+        self.lipoSpec = try getSpec(ofType: LipoToolSpec.self)
+        self.codesignSpec = try getSpec("com.apple.build-tools.codesign", ofType: CodesignToolSpec.self)
+        self.copySpec = try getSpec(ofType: CopyToolSpec.self)
+        self.copyPngSpec = try? getSpec("com.apple.build-tasks.copy-png-file", ofType: CommandLineToolSpec.self)
+        self.copyTiffSpec = try? getSpec("com.apple.build-tasks.copy-tiff-file", ofType: CommandLineToolSpec.self)
+        self.writeFileSpec = try getSpec("com.apple.build-tools.write-file", ofType: WriteFileSpec.self)
+        self.createBuildDirectorySpec = try getSpec("com.apple.tools.create-build-directory", ofType: CreateBuildDirectorySpec.self)
+        self.unifdefSpec = try getSpec("public.build-task.unifdef", ofType: UnifdefToolSpec.self)
+        self.mkdirSpec = try getSpec("com.apple.tools.mkdir", ofType: MkdirToolSpec.self)
+        self.swiftCompilerSpec = try getSpec(ofType: SwiftCompilerSpec.self)
+        self.processSDKImportsSpec = try getSpec(ProcessSDKImportsSpec.identifier, ofType: ProcessSDKImportsSpec.self)
+        self.validateDependenciesSpec = try getSpec(ValidateDependenciesSpec.identifier, ofType: ValidateDependenciesSpec.self)
     }
 
     package let specDataCaches = Registry<Spec, any SpecDataCache>()
@@ -133,8 +133,8 @@ package struct MockCommandProducer: CommandProducer, Sendable {
     package let lipoSpec: LipoToolSpec
     package let codesignSpec: CodesignToolSpec
     package let copySpec: CopyToolSpec
-    package let copyPngSpec: CommandLineToolSpec
-    package let copyTiffSpec: CommandLineToolSpec
+    package let copyPngSpec: CommandLineToolSpec?
+    package let copyTiffSpec: CommandLineToolSpec?
     package let writeFileSpec: WriteFileSpec
     package let createBuildDirectorySpec: CreateBuildDirectorySpec
     package let unifdefSpec: UnifdefToolSpec
diff --git a/Tests/SWBApplePlatformTests/AppleCommandLineSpecTests.swift b/Tests/SWBApplePlatformTests/AppleCommandLineSpecTests.swift
index 46fff813..6c258079 100644
--- a/Tests/SWBApplePlatformTests/AppleCommandLineSpecTests.swift
+++ b/Tests/SWBApplePlatformTests/AppleCommandLineSpecTests.swift
@@ -148,7 +148,7 @@ fileprivate struct AppleCommandLineSpecTests: CoreBasedTests {
     @Test
     func resMergerLinkerTaskConstruction() async throws {
         let core = try await getCore()
-        let resMergerSpec: GenericLinkerSpec = try core.specRegistry.getSpec() as ResMergerLinkerSpec
+        let resMergerSpec: GenericLinkerSpec = try core.specRegistry.getSpec(domain: "macosx", ofType: ResMergerLinkerSpec.self)
 
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
         table.push(BuiltinMacros.REZ_COLLECTOR_DIR, literal: Path.root.join("rezCollectorDir").str)
diff --git a/Tests/SWBApplePlatformTests/AppleCommandLineToolSpecDiscoveredInfoTests.swift b/Tests/SWBApplePlatformTests/AppleCommandLineToolSpecDiscoveredInfoTests.swift
index 97b45760..b30f5563 100644
--- a/Tests/SWBApplePlatformTests/AppleCommandLineToolSpecDiscoveredInfoTests.swift
+++ b/Tests/SWBApplePlatformTests/AppleCommandLineToolSpecDiscoveredInfoTests.swift
@@ -21,7 +21,7 @@ import SWBProtocol
 @Suite
 fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     func _testDiscoveredIbSpecInfo(_ spec: CommandLineToolSpec) async throws {
-        try await withSpec(spec.identifier, .deferred) { (info: DiscoveredIbtoolToolSpecInfo) in
+        try await withSpec(spec.identifier, .deferred, platform: "macosx") { (info: DiscoveredIbtoolToolSpecInfo) in
             XCTAssertMatch(info.toolPath.basename, .or(.equal("actool"), .equal("ibtool")))
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion > Version(0, 0, 0))
@@ -35,7 +35,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     @Test(.requireHostOS(.macOS))
     func discoveredActoolSpecInfo() async throws {
         // Once with the real tool
-        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec() as ActoolCompilerSpec)
+        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec(domain: "macosx", ofType: ActoolCompilerSpec.self))
 
         let output = """
             <?xml version="1.0" encoding="UTF-8"?>
@@ -54,7 +54,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
             """
 
         // ...and with fake data
-        try await withSpec(ActoolCompilerSpec.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data())) { (info: DiscoveredIbtoolToolSpecInfo) in
+        try await withSpec(ActoolCompilerSpec.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredIbtoolToolSpecInfo) in
             #expect(info.toolPath.basename == "actool")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(87946))
@@ -68,7 +68,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     @Test(.requireHostOS(.macOS))
     func discoveredIbtoolSpecInfo() async throws {
         // Once with the real tool
-        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec() as IbtoolCompilerSpecStoryboard)
+        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec(domain: "darwin", ofType: IbtoolCompilerSpecStoryboard.self))
 
         let output = """
             <?xml version="1.0" encoding="UTF-8"?>
@@ -87,7 +87,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
             """
 
         // ...and with fake data
-        try await withSpec(IbtoolCompilerSpecStoryboard.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data())) { (info: DiscoveredIbtoolToolSpecInfo) in
+        try await withSpec(IbtoolCompilerSpecStoryboard.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredIbtoolToolSpecInfo) in
             #expect(info.toolPath.basename == "ibtool")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(87946))
@@ -101,7 +101,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     @Test(.requireHostOS(.macOS))
     func discoveredStoryboardLinkerSpecInfo() async throws {
         // Once with the real tool
-        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec() as IBStoryboardLinkerCompilerSpec)
+        try await _testDiscoveredIbSpecInfo(getCore().specRegistry.getSpec(domain: "macosx", ofType: IBStoryboardLinkerCompilerSpec.self))
 
         let output = """
             <?xml version="1.0" encoding="UTF-8"?>
@@ -120,7 +120,7 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
             """
 
         // ...and with fake data
-        try await withSpec(IBStoryboardLinkerCompilerSpec.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data())) { (info: DiscoveredIbtoolToolSpecInfo) in
+        try await withSpec(IBStoryboardLinkerCompilerSpec.self, .result(status: .exit(0), stdout: Data(output.utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredIbtoolToolSpecInfo) in
             #expect(info.toolPath.basename == "ibtool")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(87946))
@@ -134,20 +134,20 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     @Test(.requireHostOS(.macOS))
     func discoveredMigSpecInfo() async throws {
         // Once with the real tool
-        try await withSpec(MigCompilerSpec.self, .deferred) { (info: DiscoveredMiGToolSpecInfo) in
+        try await withSpec(MigCompilerSpec.self, .deferred, platform: "macosx") { (info: DiscoveredMiGToolSpecInfo) in
             #expect(info.toolPath.basename == "mig")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion > Version(0, 0, 0))
         }
 
         // ...and with fake data
-        try await withSpec(MigCompilerSpec.self, .result(status: .exit(0), stdout: Data("bootstrap_cmds-108\n".utf8), stderr: Data())) { (info: DiscoveredMiGToolSpecInfo) in
+        try await withSpec(MigCompilerSpec.self, .result(status: .exit(0), stdout: Data("bootstrap_cmds-108\n".utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredMiGToolSpecInfo) in
             #expect(info.toolPath.basename == "mig")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(108))
         }
 
-        try await withSpec(MigCompilerSpec.self, .result(status: .exit(0), stdout: Data("bootstrap_cmds-99.0.0.400.6\n".utf8), stderr: Data())) { (info: DiscoveredMiGToolSpecInfo) in
+        try await withSpec(MigCompilerSpec.self, .result(status: .exit(0), stdout: Data("bootstrap_cmds-99.0.0.400.6\n".utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredMiGToolSpecInfo) in
             #expect(info.toolPath.basename == "mig")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(99, 0, 0, 400, 6))
@@ -157,14 +157,14 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
     @Test(.requireHostOS(.macOS))
     func discoveredIigSpecInfo() async throws {
         // Once with the real tool
-        try await withSpec("com.apple.compilers.iig", .deferred) { (info: DiscoveredIiGToolSpecInfo) in
+        try await withSpec("com.apple.compilers.iig", .deferred, platform: "macosx") { (info: DiscoveredIiGToolSpecInfo) in
             #expect(info.toolPath.basename == "iig")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion > Version(0, 0, 0))
         }
 
         // ...and with fake data
-        try await withSpec("com.apple.compilers.iig", .result(status: .exit(0), stdout: Data("DriverKit-29\n".utf8), stderr: Data())) { (info: DiscoveredIiGToolSpecInfo) in
+        try await withSpec("com.apple.compilers.iig", .result(status: .exit(0), stdout: Data("DriverKit-29\n".utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredIiGToolSpecInfo) in
             #expect(info.toolPath.basename == "iig")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(29))
@@ -173,20 +173,20 @@ fileprivate struct AppleCommandLineToolSpecDiscoveredInfoTests: CoreBasedTests {
 
     @Test(.requireHostOS(.macOS))
     func discoveredCoreMLSpecInfo() async throws {
-        try await withSpec(CoreMLCompilerSpec.self, .deferred) { (info: DiscoveredCoreMLToolSpecInfo) in
+        try await withSpec(CoreMLCompilerSpec.self, .deferred, platform: "macosx") { (info: DiscoveredCoreMLToolSpecInfo) in
             #expect(info.toolPath.basename == "coremlc")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion > Version(0, 0, 0))
         }
 
         // ...and with fake data
-        try await withSpec(CoreMLCompilerSpec.self, .result(status: .exit(0), stdout: Data("PROGRAM:coremlcompiler  PROJECT:CoreML-1749.0.0.0.2\nPROGRAM:coremlcompiler  PROJECT:CoreML-1749.0.0.0.2\n".utf8), stderr: Data())) { (info: DiscoveredCoreMLToolSpecInfo) in
+        try await withSpec(CoreMLCompilerSpec.self, .result(status: .exit(0), stdout: Data("PROGRAM:coremlcompiler  PROJECT:CoreML-1749.0.0.0.2\nPROGRAM:coremlcompiler  PROJECT:CoreML-1749.0.0.0.2\n".utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredCoreMLToolSpecInfo) in
             #expect(info.toolPath.basename == "coremlc")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(1749, 0, 0, 0, 2))
         }
 
-        try await withSpec(CoreMLCompilerSpec.self, .result(status: .exit(0), stdout: Data("PROGRAM:coremlc  PROJECT:IDEMLKit-999999\n".utf8), stderr: Data())) { (info: DiscoveredCoreMLToolSpecInfo) in
+        try await withSpec(CoreMLCompilerSpec.self, .result(status: .exit(0), stdout: Data("PROGRAM:coremlc  PROJECT:IDEMLKit-999999\n".utf8), stderr: Data()), platform: "macosx") { (info: DiscoveredCoreMLToolSpecInfo) in
             #expect(info.toolPath.basename == "coremlc")
             let toolVersion = try #require(info.toolVersion)
             #expect(toolVersion == Version(999999))
diff --git a/Tests/SWBBuildSystemTests/SwiftDriverTests.swift b/Tests/SWBBuildSystemTests/SwiftDriverTests.swift
index 0b56507a..309869fc 100644
--- a/Tests/SWBBuildSystemTests/SwiftDriverTests.swift
+++ b/Tests/SWBBuildSystemTests/SwiftDriverTests.swift
@@ -3685,7 +3685,7 @@ fileprivate struct SwiftDriverTests: CoreBasedTests {
                         results.checkWarnings([.contains("input unused"), .contains("input unused")], failIfNotFound: false)
 
                         func indexAndPreviewInfo(for task: any ExecutableTask) throws -> (index: SwiftSourceFileIndexingInfo?, preview: TaskGeneratePreviewInfoOutput?) {
-                            let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
+                            let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
                             let sourceFile = SRCROOT.join("Sources/file1.swift")
 
                             return (
diff --git a/Tests/SWBCorePerfTests/CommandLineSpecPerfTests.swift b/Tests/SWBCorePerfTests/CommandLineSpecPerfTests.swift
index 390aee2a..025f19d9 100644
--- a/Tests/SWBCorePerfTests/CommandLineSpecPerfTests.swift
+++ b/Tests/SWBCorePerfTests/CommandLineSpecPerfTests.swift
@@ -270,7 +270,7 @@ fileprivate struct CommandLineSpecPerfTests: CoreBasedTests, PerfTests {
     func clangCompileTaskConstruction_X1000() async throws {
         let core = try await getCore()
 
-        let clangSpec: CommandLineToolSpec = try core.specRegistry.getSpec() as ClangCompilerSpec
+        let clangSpec: CommandLineToolSpec = try core.specRegistry.getSpec(ofType: ClangCompilerSpec.self)
 
         // Create the mock table.  We include all the defaults for the tool specification.
         var (table, namespace) = clangSpec.macroTableForBuildOptionDefaults(core)
@@ -308,7 +308,7 @@ fileprivate struct CommandLineSpecPerfTests: CoreBasedTests, PerfTests {
         // Create the delegate, scope, file type, etc.
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
 
         // Create the build context for the command.
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path("/tmp/input.c"), fileType: mockFileType)], output: nil)
diff --git a/Tests/SWBCoreTests/BuildRuleTests.swift b/Tests/SWBCoreTests/BuildRuleTests.swift
index 3ca42c82..8dc68f92 100644
--- a/Tests/SWBCoreTests/BuildRuleTests.swift
+++ b/Tests/SWBCoreTests/BuildRuleTests.swift
@@ -26,16 +26,16 @@ import SWBMacro
         // Create a set of rules.  We’ll use a couple of helper functions for creating the rules.
         var rules = Array<(any BuildRuleCondition,any BuildRuleAction)>()
         func MakeNamePatternConditionTaskActionRule(_ namePattern: String, _ compilerSpecIdent: String) throws -> (any BuildRuleCondition, any BuildRuleAction) {
-            return (BuildRuleFileNameCondition(namePatterns: [core.specRegistry.internalMacroNamespace.parseString(namePattern)]), BuildRuleTaskAction(toolSpec: try core.specRegistry.getSpec(compilerSpecIdent) as CommandLineToolSpec))
+            return (BuildRuleFileNameCondition(namePatterns: [core.specRegistry.internalMacroNamespace.parseString(namePattern)]), BuildRuleTaskAction(toolSpec: try core.specRegistry.getSpec(compilerSpecIdent, ofType: CommandLineToolSpec.self)))
         }
         func MakeNamePatternConditionScriptActionRule(_ namePattern: String, _ scriptSource: String) throws -> (any BuildRuleCondition, any BuildRuleAction) {
             return (BuildRuleFileNameCondition(namePatterns: [core.specRegistry.internalMacroNamespace.parseString(namePattern)]), BuildRuleScriptAction(guid: "BR\(scriptSource)", name: "BR\(scriptSource)", interpreterPath: "/bin/sh:", scriptSource: scriptSource, inputFiles: [], inputFileLists: [], outputFiles: [], outputFileLists: [], dependencyInfo: nil, runOncePerArchitecture: true, runDuringInstallAPI: false, runDuringInstallHeaders: false))
         }
         func MakeFileTypeConditionTaskActionRule(_ fileTypeIdent: String, _ compilerSpecIdent: String) throws -> (any BuildRuleCondition, any BuildRuleAction) {
-            return (BuildRuleFileTypeCondition(fileType: try core.specRegistry.getSpec(fileTypeIdent) as FileTypeSpec), BuildRuleTaskAction(toolSpec: try core.specRegistry.getSpec(compilerSpecIdent) as CommandLineToolSpec))
+            return (BuildRuleFileTypeCondition(fileType: try core.specRegistry.getSpec(fileTypeIdent, ofType: FileTypeSpec.self)), BuildRuleTaskAction(toolSpec: try core.specRegistry.getSpec(compilerSpecIdent, ofType: CommandLineToolSpec.self)))
         }
         func MakeFileTypeConditionScriptActionRule(_ fileTypeIdent: String, _ scriptSource: String) throws -> (any BuildRuleCondition, any BuildRuleAction) {
-            return (BuildRuleFileTypeCondition(fileType: try core.specRegistry.getSpec(fileTypeIdent) as FileTypeSpec), BuildRuleScriptAction(guid: "BR\(scriptSource)", name: "BR\(scriptSource)", interpreterPath: "/bin/sh:", scriptSource: scriptSource, inputFiles: [], inputFileLists: [], outputFiles: [], outputFileLists: [], dependencyInfo: nil, runOncePerArchitecture: true, runDuringInstallAPI: false, runDuringInstallHeaders: false))
+            return (BuildRuleFileTypeCondition(fileType: try core.specRegistry.getSpec(fileTypeIdent, ofType: FileTypeSpec.self)), BuildRuleScriptAction(guid: "BR\(scriptSource)", name: "BR\(scriptSource)", interpreterPath: "/bin/sh:", scriptSource: scriptSource, inputFiles: [], inputFileLists: [], outputFiles: [], outputFileLists: [], dependencyInfo: nil, runOncePerArchitecture: true, runDuringInstallAPI: false, runDuringInstallHeaders: false))
         }
         rules.append(try MakeNamePatternConditionTaskActionRule("*.c", "com.apple.compilers.llvm.clang.1_0"))
         rules.append(try MakeNamePatternConditionScriptActionRule("*.tiff", "pwd"))
@@ -45,9 +45,9 @@ import SWBMacro
         let ruleSet = BasicBuildRuleSet(rules: rules)
 
         // Create some matchable entities.
-        let hFile = FileToBuild(absolutePath: Path.root.join("foo.h"), fileType: try core.specRegistry.getSpec(SpecRegistry.headerFileTypeIdentifiers.first!) as FileTypeSpec)
-        let cFile = FileToBuild(absolutePath: Path.root.join("foo.c"), fileType: try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec)
-        let pngFile = FileToBuild(absolutePath: Path.root.join("bar.png"), fileType: try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec)
+        let hFile = FileToBuild(absolutePath: Path.root.join("foo.h"), fileType: try core.specRegistry.getSpec(SpecRegistry.headerFileTypeIdentifiers.first!, ofType: FileTypeSpec.self))
+        let cFile = FileToBuild(absolutePath: Path.root.join("foo.c"), fileType: try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self))
+        let pngFile = FileToBuild(absolutePath: Path.root.join("bar.png"), fileType: try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self))
 
         // Create a scope for evaluation.
         let table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -103,7 +103,7 @@ import SWBMacro
 
         func testDiagnostic(enableDebugActivityLogs: Bool) throws {
             let ruleSet = DisambiguatingBuildRuleSet(rules: rules, enableDebugActivityLogs: enableDebugActivityLogs)
-            let textSpec = try core.specRegistry.getSpec("text") as FileTypeSpec
+            let textSpec = try core.specRegistry.getSpec("text", ofType: FileTypeSpec.self)
             let textFilePath = Path.root.join("tmp/foo.out")
             let textFile = FileToBuild(absolutePath: textFilePath, fileType: textSpec)
 
@@ -139,7 +139,7 @@ import SWBMacro
             BasicBuildRuleSet(rules: [rule1]),
             BasicBuildRuleSet(rules: [rule2]),
         ])
-        let textSpec = try core.specRegistry.getSpec("text") as FileTypeSpec
+        let textSpec = try core.specRegistry.getSpec("text", ofType: FileTypeSpec.self)
         let textFile = FileToBuild(absolutePath: Path.root.join("tmp/foo.out"), fileType: textSpec)
 
         let result = ruleSet.match(textFile, scope)
diff --git a/Tests/SWBCoreTests/CommandLineSpecTests.swift b/Tests/SWBCoreTests/CommandLineSpecTests.swift
index fa1c49e1..2db82fba 100644
--- a/Tests/SWBCoreTests/CommandLineSpecTests.swift
+++ b/Tests/SWBCoreTests/CommandLineSpecTests.swift
@@ -166,8 +166,8 @@ import SWBMacro
     @Test(.requireHostOS(.macOS))
     func swiftTaskConstruction() async throws {
         let core = try await getCore()
-        let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
-        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool") as SwiftHeaderToolSpec
+        let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
+        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool", ofType: SwiftHeaderToolSpec.self)
 
         let swiftCompilerPath = try await self.swiftCompilerPath
 
@@ -212,9 +212,9 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/one.swift"), fileType: mockFileType), FileToBuild(absolutePath: Path.root.join("tmp/two.swift"), fileType: mockFileType)]
-        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
         await swiftSpec.constructTasks(cbc, delegate)
         headerSpec.constructSwiftHeaderToolTask(cbc, delegate, inputs: delegate.generatedSwiftObjectiveCHeaderFiles(), outputPath: Path("App1-Swift.h"))
@@ -307,9 +307,9 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/one.swift"), fileType: mockFileType), FileToBuild(absolutePath: Path.root.join("tmp/two.swift"), fileType: mockFileType)]
-            let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+            let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
             await swiftSpec.constructTasks(cbc, delegate)
             headerSpec.constructSwiftHeaderToolTask(cbc, delegate, inputs: delegate.generatedSwiftObjectiveCHeaderFiles(), outputPath: Path.root.join("tmp/output/obj/DerivedFiles/App1-Swift.h"))
@@ -323,8 +323,8 @@ import SWBMacro
     @Test(.requireHostOS(.macOS), .requireLLBuild(apiVersion: 12))
     func swiftTaskConstruction_integratedDriver() async throws {
         let core = try await getCore()
-        let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
-        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool") as SwiftHeaderToolSpec
+        let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
+        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool", ofType: SwiftHeaderToolSpec.self)
 
         let swiftCompilerPath = try await self.swiftCompilerPath
 
@@ -371,9 +371,9 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/one.swift"), fileType: mockFileType), FileToBuild(absolutePath: Path.root.join("tmp/two.swift"), fileType: mockFileType)]
-        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
         await swiftSpec.constructTasks(cbc, delegate)
         headerSpec.constructSwiftHeaderToolTask(cbc, delegate, inputs: delegate.generatedSwiftObjectiveCHeaderFiles(), outputPath: Path("App1-Swift.h"))
@@ -490,9 +490,9 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/one.swift"), fileType: mockFileType), FileToBuild(absolutePath: Path.root.join("tmp/two.swift"), fileType: mockFileType)]
-            let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+            let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
             await swiftSpec.constructTasks(cbc, delegate)
             headerSpec.constructSwiftHeaderToolTask(cbc, delegate, inputs: delegate.generatedSwiftObjectiveCHeaderFiles(), outputPath: Path.root.join("tmp/output/obj/DerivedFiles/App1-Swift.h"))
@@ -507,8 +507,8 @@ import SWBMacro
     @Test(.requireSDKs(.macOS))
     func swiftTaskConstructionWithoutResponseFile() async throws {
         let core = try await getCore()
-        let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
-        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool") as SwiftHeaderToolSpec
+        let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
+        let headerSpec = try core.specRegistry.getSpec("com.apple.build-tools.swift-header-tool", ofType: SwiftHeaderToolSpec.self)
 
         let swiftCompilerPath = try await self.swiftCompilerPath
 
@@ -549,9 +549,9 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/one.swift"), fileType: mockFileType), FileToBuild(absolutePath: Path.root.join("tmp/two.swift"), fileType: mockFileType)]
-        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
         await swiftSpec.constructTasks(cbc, delegate)
         headerSpec.constructSwiftHeaderToolTask(cbc, delegate, inputs: delegate.generatedSwiftObjectiveCHeaderFiles(), outputPath: Path("App1-Swift.h"))
@@ -600,7 +600,7 @@ import SWBMacro
     @Test(.skipHostOS(.windows, "tmp/not-mainone.swift not in command line"))
     func singleFileSwiftTaskConstruction() async throws {
         let core = try await getCore()
-        let swiftSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
+        let swiftSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
 
         // Create the mock table.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -620,9 +620,9 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let inputFiles = [FileToBuild(absolutePath: Path.root.join("tmp/not-mainone.swift"), fileType: mockFileType)]
-        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx") as ArchitectureSpec
+        let archSpec = try core.specRegistry.getSpec("x86_64", domain: "macosx", ofType: ArchitectureSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: inputFiles, currentArchSpec: archSpec, output: nil)
         await swiftSpec.constructTasks(cbc, delegate)
 
@@ -643,7 +643,7 @@ import SWBMacro
     @Test
     func stripTaskConstruction() async throws {
         let core = try await getCore()
-        let stripSpec = try core.specRegistry.getSpec("com.apple.build-tools.strip") as CommandLineToolSpec
+        let stripSpec = try core.specRegistry.getSpec("com.apple.build-tools.strip", ofType: CommandLineToolSpec.self)
 
         // Create the mock table.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -653,7 +653,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+                   let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input"), fileType: mockFileType)], output: Path.root.join("tmp/output"))
         await stripSpec.constructTasks(cbc, delegate)
 
@@ -669,7 +669,7 @@ import SWBMacro
     @Test(.requireSDKs(.macOS))
     func swiftStdlibTool() async throws {
         let core = try await getCore()
-        let stdlibTool = try core.specRegistry.getSpec("com.apple.build-tools.swift-stdlib-tool") as SwiftStdLibToolSpec
+        let stdlibTool = try core.specRegistry.getSpec("com.apple.build-tools.swift-stdlib-tool", ofType: SwiftStdLibToolSpec.self)
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
         table.push(BuiltinMacros.CODESIGN_ALLOCATE, literal: "/path/to/codesign_allocate")
         table.push(BuiltinMacros.WRAPPER_NAME, literal: "wrapper")
@@ -677,7 +677,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.application", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input"), fileType: mockFileType)], output: nil)
 
         // Check that task construction sets the correct env bindings.
@@ -691,7 +691,7 @@ import SWBMacro
     @Test
     func dsymutilTaskConstruction() async throws {
         let core = try await getCore()
-        let dsymutilSpec = try core.specRegistry.getSpec("com.apple.tools.dsymutil") as DsymutilToolSpec
+        let dsymutilSpec = try core.specRegistry.getSpec("com.apple.tools.dsymutil", ofType: DsymutilToolSpec.self)
 
         do {
             var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -702,7 +702,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+                       let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input"), fileType: mockFileType)], output: Path.root.join("tmp/output"))
             await dsymutilSpec.constructTasks(cbc, delegate, dsymBundle: Path.root.join("tmp/output.dSYM"))
 
@@ -725,7 +725,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input"), fileType: mockFileType)], output: Path.root.join("tmp/output"))
             await dsymutilSpec.constructTasks(cbc, delegate, dsymBundle: Path.root.join("tmp/output.dSYM"))
 
@@ -742,7 +742,7 @@ import SWBMacro
     @Test(.skipHostOS(.windows, "prefix.h header path is coming over as tmp\\tmp\\prefix.h"), .requireSDKs(.macOS))
     func clangCompileTaskConstruction() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
 
         // Create the mock table.  We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -804,7 +804,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self)
 
             // Create the build context for the command.
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input.c"), fileType: mockFileType)], output: nil)
@@ -861,7 +861,7 @@ import SWBMacro
     @Test
     func clangCompileWithPrefixHeaderTaskConstruction() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
 
         // Create the mock table.  We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -908,7 +908,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self)
 
         // We need to construct multiple tasks to ensure that they correctly share one precompiled header
         let numCompileTasks = 2
@@ -988,7 +988,7 @@ import SWBMacro
     @Test
     func clangCompileTaskConstructionWithCXXModulesDisabled() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
 
         // Create the dummy table.  We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1023,7 +1023,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let dummyScope = MacroEvaluationScope(table: table)
-            let dummyFileType = try core.specRegistry.getSpec(spec) as FileTypeSpec
+            let dummyFileType = try core.specRegistry.getSpec(spec, ofType: FileTypeSpec.self)
 
             let fileSuffix = spec.hasSuffix("objcpp") ? ".mm" : ".m"
             // Create the build context for the command.
@@ -1078,7 +1078,7 @@ import SWBMacro
     @Test
     func clangCompileTaskConstructionWithCXX20ModulesDisabled() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
 
         // Create the dummy table.  We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1115,7 +1115,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let dummyScope = MacroEvaluationScope(table: configTable)
-            let dummyFileType = try core.specRegistry.getSpec(spec) as FileTypeSpec
+            let dummyFileType = try core.specRegistry.getSpec(spec, ofType: FileTypeSpec.self)
 
             // Create the build context for the command.
             let cbc = CommandBuildContext(producer: producer, scope: dummyScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input.mm"), fileType: dummyFileType)], output: nil)
@@ -1186,7 +1186,7 @@ import SWBMacro
     @Test(.skipHostOS(.windows, "output file is coming out as tmp\\input.o (non-absolute)"))
     func cCompilerLauncher() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
 
         // Create the mock table.  We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1196,7 +1196,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("sourcecode.c") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("sourcecode.c", ofType: FileTypeSpec.self)
 
         // Create the build context for the command.
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input.c"), fileType: mockFileType)], output: nil)
@@ -1217,8 +1217,8 @@ import SWBMacro
     @Test
     func cppLanguageStandard() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
-        let mockFileType = try core.specRegistry.getSpec("sourcecode.cpp.cpp") as FileTypeSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
+        let mockFileType = try core.specRegistry.getSpec("sourcecode.cpp.cpp", ofType: FileTypeSpec.self)
         let langStandardMacro = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("CLANG_CXX_LANGUAGE_STANDARD") as? StringMacroDeclaration)
 
         let macroFlagMapping = [
@@ -1254,12 +1254,12 @@ import SWBMacro
     @Test
     func compilerPathOverrides() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
         let fileTypes = [
-            ".c": try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec,
-            ".cpp": try core.specRegistry.getSpec("sourcecode.cpp.cpp") as FileTypeSpec,
-            ".m": try core.specRegistry.getSpec("sourcecode.c.objc") as FileTypeSpec,
-            ".mm": try core.specRegistry.getSpec("sourcecode.cpp.objcpp") as FileTypeSpec
+            ".c": try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self),
+            ".cpp": try core.specRegistry.getSpec("sourcecode.cpp.cpp", ofType: FileTypeSpec.self),
+            ".m": try core.specRegistry.getSpec("sourcecode.c.objc", ofType: FileTypeSpec.self),
+            ".mm": try core.specRegistry.getSpec("sourcecode.cpp.objcpp", ofType: FileTypeSpec.self)
         ]
 
         // Check with just CC.
@@ -1321,7 +1321,7 @@ import SWBMacro
     @Test
     func linkerTaskConstruction() async throws {
         let core = try await getCore()
-        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec() as LdLinkerSpec
+        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec(ofType: LdLinkerSpec.self)
 
         // Create the mock table.
         // Since these tests don't use any of the default settings, we need to push any defaults needed for the test here.
@@ -1337,7 +1337,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/obj/normal/x86_64/file1.o"), fileType: mockFileType)], output: Path.root.join("tmp/obj/normal/x86_64/output"))
 
         // Test all permutations of library kind, linkage mode and search path usage, except for object files and object libraries.
@@ -1439,7 +1439,7 @@ import SWBMacro
     @Test
     func linkerBuildSettings() async throws {
         let core = try await getCore()
-        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec() as LdLinkerSpec
+        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec(ofType: LdLinkerSpec.self)
         let variant = "normal"
         let arch = "arm64"
 
@@ -1449,7 +1449,7 @@ import SWBMacro
         baseTable.push(BuiltinMacros.variant, literal: variant)
 
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
 
         /// Utility method to add the setting to the table, create a task with the table, and call a checker block.
         func createAndCheckLinkerTask(_ name: String, type: MacroDeclaration.Type, value: String, check: (PlannedTaskBuilder) async throws -> Void) async throws {
@@ -1493,7 +1493,7 @@ import SWBMacro
     @Test
     func linkerAdHocSigningOptions() async throws {
         let core = try await getCore()
-        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec() as LdLinkerSpec
+        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec(ofType: LdLinkerSpec.self)
 
         // Create the mock table, which will get re-used across the tests.We include all the defaults for the tool specification.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1512,7 +1512,7 @@ import SWBMacro
 
         // Construct data we can re-use across the tests.
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
-        let mockFileType: FileTypeSpec = try core.specRegistry.getSpec("file")
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
 
         // Test linking for different macOS archs with a signing identity.
         // Presently we disable ad-hoc code signing always when we have a signing identity.
@@ -1574,7 +1574,7 @@ import SWBMacro
     @Test
     func libtoolTaskConstruction() async throws {
         let core = try await getCore()
-        let librarianSpec: LinkerSpec = try core.specRegistry.getSpec() as LibtoolLinkerSpec
+        let librarianSpec: LinkerSpec = try core.specRegistry.getSpec(ofType: LibtoolLinkerSpec.self)
 
         // Create the mock table.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1586,7 +1586,7 @@ import SWBMacro
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.library.static", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
         let mockScope = MacroEvaluationScope(table: table)
-        let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/obj/normal/x86_64/file1.o"), fileType: mockFileType)], output: Path.root.join("tmp/obj/normal/x86_64/output"))
         let libraries = [
             LinkerSpec.LibrarySpecifier(kind: .static, path: Path.root.join("usr/lib/libfoo1.a"), mode: .normal, useSearchPaths: true, swiftModulePaths: [:], swiftModuleAdditionalLinkerArgResponseFilePaths: [:]),
@@ -1641,11 +1641,11 @@ import SWBMacro
     @Test
     func linkerPathOverrides() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
-        let spec: LinkerSpec = try core.specRegistry.getSpec() as LdLinkerSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
+        let spec: LinkerSpec = try core.specRegistry.getSpec(ofType: LdLinkerSpec.self)
         let fileTypes = [
-            ".c": try core.specRegistry.getSpec("sourcecode.c.c") as FileTypeSpec,
-            ".cpp": try core.specRegistry.getSpec("sourcecode.cpp.cpp") as FileTypeSpec,
+            ".c": try core.specRegistry.getSpec("sourcecode.c.c", ofType: FileTypeSpec.self),
+            ".cpp": try core.specRegistry.getSpec("sourcecode.cpp.cpp", ofType: FileTypeSpec.self),
         ]
 
         func check(name: String, expectedLinker: String, macros: [StringMacroDeclaration: String], sourceLocation: SourceLocation = #_sourceLocation) async throws {
@@ -1698,9 +1698,9 @@ import SWBMacro
     @Test
     func additionalLinkerArgs() async throws {
         let core = try await getCore()
-        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec() as LdLinkerSpec
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
-        let objcFileTypeSpec = try core.specRegistry.getSpec("sourcecode.c.objc") as FileTypeSpec
+        let linkerSpec: LinkerSpec = try core.specRegistry.getSpec(ofType: LdLinkerSpec.self)
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
+        let objcFileTypeSpec = try core.specRegistry.getSpec("sourcecode.c.objc", ofType: FileTypeSpec.self)
         let macroName = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("LLVM_LTO") as? StringMacroDeclaration)
 
         let macroValues = [
@@ -1739,7 +1739,7 @@ import SWBMacro
     @Test
     func copyTaskConstruction() async throws {
         let core = try await getCore()
-        let copySpec = try core.specRegistry.getSpec() as CopyToolSpec
+        let copySpec = try core.specRegistry.getSpec(ofType: CopyToolSpec.self)
 
         // Create the mock table. Note that the defaults from the spec are *not* added to this table.
         var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -1751,7 +1751,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/file-to-copy"), fileType: mockFileType)], output: Path.root.join("tmp/dst/file-to-copy"))
             await copySpec.constructCopyTasks(cbc, delegate)
 
@@ -1770,7 +1770,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/file-to-copy"), fileType: mockFileType)], output: Path.root.join("tmp/dst/file-to-copy"))
             await copySpec.constructCopyTasks(cbc, delegate, removeHeaderDirectories: true)
 
@@ -1789,7 +1789,7 @@ import SWBMacro
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
             let mockScope = MacroEvaluationScope(table: table)
-            let mockFileType = try core.specRegistry.getSpec("file") as FileTypeSpec
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/file-to-copy"), fileType: mockFileType)], output: Path.root.join("tmp/dst/file-to-copy"))
             await copySpec.constructCopyTasks(cbc, delegate, ignoreMissingInputs: true)
 
@@ -1808,14 +1808,14 @@ import SWBMacro
     @Test
     func touchTaskConstruction() async throws {
         let core = try await getCore()
-        let touchSpec = try #require(core.specRegistry.getSpec("com.apple.tools.touch") as? CommandLineToolSpec)
+        let touchSpec = try core.specRegistry.getSpec("com.apple.tools.touch", ofType: CommandLineToolSpec.self)
 
         let table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
         let scope = MacroEvaluationScope(table: table)
 
         let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
         let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
-        let mockFileType = try #require(core.specRegistry.getSpec("file") as? FileTypeSpec)
+        let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let cbc = CommandBuildContext(producer: producer, scope: scope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/input"), fileType: mockFileType)])
         await touchSpec.constructTasks(cbc, delegate)
 
@@ -1836,7 +1836,7 @@ import SWBMacro
     @Test
     func symlinkTaskConstruction() async throws {
         let core = try await getCore()
-        let symlinkSpec = try #require(core.specRegistry.getSpec("com.apple.tools.symlink") as? SymlinkToolSpec)
+        let symlinkSpec = try core.specRegistry.getSpec("com.apple.tools.symlink", ofType: SymlinkToolSpec.self)
 
         let table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
         let scope = MacroEvaluationScope(table: table)
@@ -1857,7 +1857,7 @@ import SWBMacro
     @Test
     func mkdirTaskConstruction() async throws {
         let core = try await getCore()
-        let mkdirSpec = try #require(core.specRegistry.getSpec("com.apple.tools.mkdir") as? MkdirToolSpec)
+        let mkdirSpec = try core.specRegistry.getSpec("com.apple.tools.mkdir", ofType: MkdirToolSpec.self)
 
         let table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
         let scope = MacroEvaluationScope(table: table)
@@ -1882,7 +1882,7 @@ import SWBMacro
             // any spec is fine, we're testing the lookup function
             let delegate = TestingCoreDelegate()
             let core = try await Self.makeCore(simulatedInferiorProductsPath: nil, delegate)
-            let spec: CommandLineToolSpec = try core.specRegistry.getSpec("com.apple.tools.touch")
+            let spec = try core.specRegistry.getSpec("com.apple.tools.touch", ofType: CommandLineToolSpec.self)
 
             let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
             let namespace = BuiltinMacros.namespace
@@ -1891,7 +1891,7 @@ import SWBMacro
                 table.push(macro, namespace.parseLiteralString(Path.root.join("tmp").str))
             }
             let scope = MacroEvaluationScope(table: table)
-            let mockFileType = try #require(core.specRegistry.getSpec("file") as? FileTypeSpec)
+            let mockFileType = try core.specRegistry.getSpec("file", ofType: FileTypeSpec.self)
             let cbc = CommandBuildContext(producer: producer, scope: scope, inputs: (0..<numberOfInputs).map({ FileToBuild(absolutePath: Path.root.join("tmp/file\($0 + 1).c"), fileType: mockFileType) }), output: output ? Path.root.join("tmp/output.c") : nil)
             #expect(spec.lookup(macro, cbc, core.delegate)?.asLiteralString == expectation)
 
@@ -1953,8 +1953,8 @@ import SWBMacro
     @Test
     func clangDepscanPrefixMap() async throws {
         let core = try await getCore()
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CommandLineToolSpec
-        let mockFileType = try core.specRegistry.getSpec("sourcecode.cpp.cpp") as FileTypeSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CommandLineToolSpec.self)
+        let mockFileType = try core.specRegistry.getSpec("sourcecode.cpp.cpp", ofType: FileTypeSpec.self)
         let enableCompileCache = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("CLANG_ENABLE_COMPILE_CACHE") as? BooleanMacroDeclaration)
         let enablePrefixMap = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("CLANG_ENABLE_PREFIX_MAPPING") as? BooleanMacroDeclaration)
         let prefixMaps = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("CLANG_OTHER_PREFIX_MAPPINGS") as? StringListMacroDeclaration)
@@ -2006,9 +2006,9 @@ import SWBMacro
     @Test
     func swiftCachingPrefixMap() async throws {
         let core = try await getCore()
-        let swiftSpec = try core.specRegistry.getSpec("com.apple.xcode.tools.swift.compiler") as CompilerSpec
+        let swiftSpec = try core.specRegistry.getSpec("com.apple.xcode.tools.swift.compiler", ofType: CompilerSpec.self)
 
-        let mockFileType = try core.specRegistry.getSpec("sourcecode.swift") as FileTypeSpec
+        let mockFileType = try core.specRegistry.getSpec("sourcecode.swift", ofType: FileTypeSpec.self)
         let enableCompileCache = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("SWIFT_ENABLE_COMPILE_CACHE") as? BooleanMacroDeclaration)
         let enablePrefixMap = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("SWIFT_ENABLE_PREFIX_MAPPING") as? BooleanMacroDeclaration)
         let prefixMaps = try #require(core.specRegistry.internalMacroNamespace.lookupMacroDeclaration("SWIFT_OTHER_PREFIX_MAPPINGS") as? StringListMacroDeclaration)
@@ -2227,7 +2227,7 @@ import SWBMacro
 
             do {
                 // Get the tool spec.
-                let thingSpec = try core.specRegistry.getSpec(ThingToolSpec.identifier) as ThingToolSpec
+                let thingSpec = try core.specRegistry.getSpec(ThingToolSpec.identifier, ofType: ThingToolSpec.self)
 
                 // Create a table with the unioned tool defaults, and any other values we want to add.
                 var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -2238,7 +2238,7 @@ import SWBMacro
                 let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
                 let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
                 let mockScope = MacroEvaluationScope(table: table)
-                let mockFileType = try core.specRegistry.getSpec("file.thing") as FileTypeSpec
+                let mockFileType = try core.specRegistry.getSpec("file.thing", ofType: FileTypeSpec.self)
                 let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/file.thing"), fileType: mockFileType)], output: Path.root.join("tmp/dst/file.something"), resourcesDir: Path.root.join("tmp/dst"), unlocalizedResourcesDir: Path.root.join("tmp/dst"))
                 await thingSpec.constructTasks(cbc, delegate)
 
@@ -2272,7 +2272,7 @@ import SWBMacro
 
             do {
                 // Get the tool spec.
-                let thingSpec = try core.specRegistry.getSpec(ThingToolSpec.identifier) as ThingToolSpec
+                let thingSpec = try core.specRegistry.getSpec(ThingToolSpec.identifier, ofType: ThingToolSpec.self)
 
                 // Create a table with the unioned tool defaults, and any other values we want to add.
                 var table = MacroValueAssignmentTable(namespace: core.specRegistry.internalMacroNamespace)
@@ -2283,7 +2283,7 @@ import SWBMacro
                 let producer = try MockCommandProducer(core: core, productTypeIdentifier: "com.apple.product-type.framework", platform: "macosx")
                 let delegate = try CapturingTaskGenerationDelegate(producer: producer, userPreferences: .defaultForTesting)
                 let mockScope = MacroEvaluationScope(table: table)
-                let mockFileType = try core.specRegistry.getSpec("file.thing") as FileTypeSpec
+                let mockFileType = try core.specRegistry.getSpec("file.thing", ofType: FileTypeSpec.self)
                 let cbc = CommandBuildContext(producer: producer, scope: mockScope, inputs: [FileToBuild(absolutePath: Path.root.join("tmp/file.thing"), fileType: mockFileType, regionVariantName: "en")], output: Path.root.join("tmp/dst/file.something"), resourcesDir: Path.root.join("tmp/dst/en.lproj"), unlocalizedResourcesDir: Path.root.join("tmp/dst"))
                 await thingSpec.constructTasks(cbc, delegate)
 
diff --git a/Tests/SWBCoreTests/FileToBuildTests.swift b/Tests/SWBCoreTests/FileToBuildTests.swift
index ec83f217..673e6682 100644
--- a/Tests/SWBCoreTests/FileToBuildTests.swift
+++ b/Tests/SWBCoreTests/FileToBuildTests.swift
@@ -20,7 +20,7 @@ import SWBCore
     /// Tests the basic FileToBuild functionality.
     @Test
     func basics() async throws {
-        let mockFileType = try await getCore().specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try await getCore().specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let f = FileToBuild(absolutePath: Path.root.join("tmp/foo"), fileType: mockFileType)
         #expect(f.absolutePath == Path.root.join("tmp/foo"))
     }
@@ -30,7 +30,7 @@ import SWBCore
     /// Tests the basic FileToBuildGroup functionality.
     @Test
     func basics() async throws {
-        let mockFileType = try await getCore().specRegistry.getSpec("file") as FileTypeSpec
+        let mockFileType = try await getCore().specRegistry.getSpec("file", ofType: FileTypeSpec.self)
         let f1 = FileToBuild(absolutePath: Path.root.join("tmp").join("foo"), fileType: mockFileType)
         #expect(f1.absolutePath == Path.root.join("tmp").join("foo"))
         let f2 = FileToBuild(absolutePath: Path.root.join("tmp").join("bar"), fileType: mockFileType)
diff --git a/Tests/SWBCoreTests/SDKRegistryTests.swift b/Tests/SWBCoreTests/SDKRegistryTests.swift
index 73d1b6bf..3e28f055 100644
--- a/Tests/SWBCoreTests/SDKRegistryTests.swift
+++ b/Tests/SWBCoreTests/SDKRegistryTests.swift
@@ -564,7 +564,7 @@ import SWBMacro
                 }
 
                 let toastVariant = try #require(toastSDK.variants["toastos"])
-                let toastAppSpec: ProductTypeSpec = try core.specRegistry.getSpec("com.apple.product-type.application", domain: "embedded")
+                let toastAppSpec: ProductTypeSpec = try core.specRegistry.getSpec("com.apple.product-type.application", domain: "embedded", ofType: ProductTypeSpec.self)
 
                 table.push(BuiltinMacros.TARGETED_DEVICE_FAMILY, literal: "1,2")
                 scope = MacroEvaluationScope(table: table)
@@ -596,7 +596,7 @@ import SWBMacro
                 #expect(effectiveIds == Set([7]))
 
                 let iosmacVariant = try #require(macosBorkSDK.variants["iosmac"])
-                let macAppSpec: ProductTypeSpec = try core.specRegistry.getSpec("com.apple.product-type.application", domain: "macosx")
+                let macAppSpec: ProductTypeSpec = try core.specRegistry.getSpec("com.apple.product-type.application", domain: "macosx", ofType: ProductTypeSpec.self)
 
                 table.remove(BuiltinMacros.TARGETED_DEVICE_FAMILY)
                 scope = MacroEvaluationScope(table: table)
diff --git a/Tests/SWBCoreTests/SpecLoadingTests.swift b/Tests/SWBCoreTests/SpecLoadingTests.swift
index ba135228..52f49368 100644
--- a/Tests/SWBCoreTests/SpecLoadingTests.swift
+++ b/Tests/SWBCoreTests/SpecLoadingTests.swift
@@ -126,7 +126,7 @@ import SWBMacro
     func archSpecLoading() async throws {
         let core = try await getCore()
         // Validate that we can load an arch spec properly.
-        let standardArchs = try core.specRegistry.getSpec("Standard", domain: "macosx") as ArchitectureSpec
+        let standardArchs = try core.specRegistry.getSpec("Standard", domain: "macosx", ofType: ArchitectureSpec.self)
         #expect(standardArchs.archSetting?.name == "ARCHS_STANDARD")
         #expect(standardArchs.realArchs?.stringRep == "arm64 x86_64")
     }
@@ -147,7 +147,7 @@ import SWBMacro
         for spec in core.specRegistry.findSpecs(ProductTypeSpec.self, domain: domain) {
             func check<T>(identifier: String, is: T.Type, sourceLocation: SourceLocation = #_sourceLocation) {
                 #expect(throws: Never.self) {
-                    try core.specRegistry.getSpec(identifier, domain: domain) as ProductTypeSpec
+                    try core.specRegistry.getSpec(identifier, domain: domain, ofType: ProductTypeSpec.self)
                 }
                 if spec.conformsTo(identifier: identifier) {
                     #expect(spec is T, "\(spec) is not an instance of \(T.self)", sourceLocation: sourceLocation)
@@ -854,7 +854,7 @@ import SWBMacro
     /// Validate that we can load a known command line spec properly.
     @Test
     func commandLineSpecLoading() async throws {
-        let infoPlistUtilSpec = try await getCore().specRegistry.getSpec("com.apple.tools.info-plist-utility") as CommandLineToolSpec
+        let infoPlistUtilSpec = try await getCore().specRegistry.getSpec("com.apple.tools.info-plist-utility", ofType: CommandLineToolSpec.self)
         #expect(infoPlistUtilSpec.execDescription!.stringRep.hasPrefix("Process"))
 
         // Check diagnostics using synthetic data.
@@ -896,7 +896,7 @@ import SWBMacro
     @Test
     func environmentVariableConsistentOrdering() async throws {
         let core = try await getCore()
-        let migSpec: CompilerSpec = try core.specRegistry.getSpec("com.apple.compilers.mig") as CompilerSpec
+        let migSpec: CompilerSpec = try core.specRegistry.getSpec("com.apple.compilers.mig", domain: "macosx", ofType: CompilerSpec.self)
         #expect(migSpec.environmentVariables?.map({ $0.0 }) == ["DEVELOPER_DIR", "SDKROOT", "TOOLCHAINS"])
     }
 
@@ -906,19 +906,19 @@ import SWBMacro
         let core = try await getCore()
 
         // Validate that we can load a compiler spec properly.
-        let clangCompilerSpec: CompilerSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0.compiler") as ClangCompilerSpec
+        let clangCompilerSpec: CompilerSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0.compiler", ofType: ClangCompilerSpec.self)
 
         // Validate that non-custom implementations get the custom subclass.
-        #expect(core.specRegistry.getSpec("com.apple.build-tasks.copy-png-file")! is GenericCompilerSpec)
+        #expect(core.specRegistry.getSpec("com.apple.build-tasks.copy-png-file", domain: "macosx")! is GenericCompilerSpec)
 
         // Validate that we properly fetch the Class field from the base spec.
-        let analyzerSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0.analyzer") as CompilerSpec
+        let analyzerSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0.analyzer", ofType: CompilerSpec.self)
         #expect(analyzerSpec is ClangCompilerSpec)
         let analyzerSpecIPhone = try #require(core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0.analyzer", domain: "iphoneos"))
         #expect(analyzerSpecIPhone is ClangCompilerSpec)
 
         // Validate that we parse other properties from the base spec.
-        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0") as CompilerSpec
+        let clangSpec = try core.specRegistry.getSpec("com.apple.compilers.llvm.clang.1_0", ofType: CompilerSpec.self)
         #expect(clangSpec.execDescription == clangCompilerSpec.execDescription)
 
         // Validate overridden class loading.
@@ -926,7 +926,7 @@ import SWBMacro
         #expect(codesignSpec is CodesignToolSpec)
 
         // Validate loading of supported language versions
-        let swiftCompilerSpec = try core.specRegistry.getSpec() as SwiftCompilerSpec
+        let swiftCompilerSpec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
         #expect(swiftCompilerSpec.supportedLanguageVersions == [ Version(4,0), Version(4,2), Version(5,0), Version(6, 0)])
     }
 
@@ -994,7 +994,7 @@ import SWBMacro
     /// Validate that we can load a linker spec properly.
     @Test
     func linkerSpecLoading() async throws {
-        try #require(try await (getCore().specRegistry.getSpec() as LdLinkerSpec).execDescription?.stringRep.hasPrefix("Link") == true)
+        try #require(try await (getCore().specRegistry.getSpec(ofType: LdLinkerSpec.self)).execDescription?.stringRep.hasPrefix("Link") == true)
     }
 
     /// Validate there are no cases of domain inversion.
diff --git a/Tests/SWBCoreTests/SwiftCompilerTests.swift b/Tests/SWBCoreTests/SwiftCompilerTests.swift
index f37311db..48d6d76e 100644
--- a/Tests/SWBCoreTests/SwiftCompilerTests.swift
+++ b/Tests/SWBCoreTests/SwiftCompilerTests.swift
@@ -126,7 +126,7 @@ fileprivate final class TestSwiftParserDelegate: TaskOutputParserDelegate, Senda
             return localFS.exists(stdlibPath) ? [["-L\(stdlibPath.str)"], ["-L/usr/lib/swift"]] : [["-L/usr/lib/swift"]]
         }
 
-        let spec = try core.specRegistry.getSpec() as SwiftCompilerSpec
+        let spec = try core.specRegistry.getSpec(ofType: SwiftCompilerSpec.self)
 
         let defaultToolchain = try #require(core.toolchainRegistry.defaultToolchain)
         let swiftcPath = defaultToolchain.path.join("usr/bin/swiftc")
diff --git a/Tests/SWBTaskExecutionTests/InfoPlistProcessorTaskTests.swift b/Tests/SWBTaskExecutionTests/InfoPlistProcessorTaskTests.swift
index c099461c..37aaba35 100644
--- a/Tests/SWBTaskExecutionTests/InfoPlistProcessorTaskTests.swift
+++ b/Tests/SWBTaskExecutionTests/InfoPlistProcessorTaskTests.swift
@@ -41,7 +41,7 @@ fileprivate struct InfoPlistProcessorTaskTests: CoreBasedTests {
         // Look up the product type.
         var productType: ProductTypeSpec? = nil
         if let productTypeId {
-            productType = try core.specRegistry.getSpec(productTypeId, domain: platformName) as ProductTypeSpec
+            productType = try core.specRegistry.getSpec(productTypeId, domain: platformName, ofType: ProductTypeSpec.self)
         }
 
         // Create the task action.
@@ -1152,7 +1152,7 @@ fileprivate struct InfoPlistProcessorTaskTests: CoreBasedTests {
             }
             let productTypeSpec: ProductTypeSpec?
             do {
-                productTypeSpec = try productType.map { try core.specRegistry.getSpec($0, domain: platformName) as ProductTypeSpec }
+                productTypeSpec = try productType.map { try core.specRegistry.getSpec($0, domain: platformName, ofType: ProductTypeSpec.self) }
             } catch {
                 Issue.record("\(error)")
                 return