diff --git a/doc/ReleaseNotes.md b/doc/ReleaseNotes.md
index 57c970aeb6..2d1b8900a1 100644
--- a/doc/ReleaseNotes.md
+++ b/doc/ReleaseNotes.md
@@ -4,4 +4,4 @@ Nothing yet.
 
 ## Bug Fixes
 
-* None yet
+* Refactored source type handling to use a `SourceType` enum with centralized string conversion, and added stronger `source add` type validation (#4463).
diff --git a/src/AppInstallerCLICore/Commands/DscSourceResource.cpp b/src/AppInstallerCLICore/Commands/DscSourceResource.cpp
index 733a254879..4323cc67a0 100644
--- a/src/AppInstallerCLICore/Commands/DscSourceResource.cpp
+++ b/src/AppInstallerCLICore/Commands/DscSourceResource.cpp
@@ -107,7 +107,7 @@ namespace AppInstaller::CLI
                     {
                         Output.Exist(true);
                         Output.Argument(source.Arg);
-                        Output.Type(source.Type);
+                        Output.Type(std::string{ SourceTypeEnumToString(source.Type) });
                         Output.TrustLevel(TrustLevelStringFromFlags(source.TrustLevel));
                         Output.Explicit(source.Explicit);
 
@@ -495,7 +495,7 @@ namespace AppInstaller::CLI
             SourceResourceObject output;
             output.SourceName(source.Name);
             output.Argument(source.Arg);
-            output.Type(source.Type);
+            output.Type(std::string{ SourceTypeEnumToString(source.Type) });
             output.TrustLevel(TrustLevelStringFromFlags(source.TrustLevel));
             output.Explicit(source.Explicit);
 
diff --git a/src/AppInstallerCLICore/Commands/SourceCommand.cpp b/src/AppInstallerCLICore/Commands/SourceCommand.cpp
index aa820c9277..8b4ee09410 100644
--- a/src/AppInstallerCLICore/Commands/SourceCommand.cpp
+++ b/src/AppInstallerCLICore/Commands/SourceCommand.cpp
@@ -94,6 +94,22 @@ namespace AppInstaller::CLI
 
     void SourceAddCommand::ValidateArgumentsInternal(Args& execArgs) const
     {
+        if (execArgs.Contains(Execution::Args::Type::SourceType))
+        {
+            std::string_view sourceTypeArg = execArgs.GetArg(Execution::Args::Type::SourceType);
+            auto validOptions = std::vector<Utility::LocIndString>{
+                Utility::LocIndString{ Repository::SourceTypeEnumToString(Repository::SourceType::PreIndexedPackage) },
+                Utility::LocIndString{ Repository::SourceTypeEnumToString(Repository::SourceType::Rest) } };
+
+            auto sourceType = Repository::TryConvertToSourceTypeEnum(sourceTypeArg);
+            bool isUserAddType = sourceType.has_value() &&
+                (sourceType.value() == Repository::SourceType::PreIndexedPackage || sourceType.value() == Repository::SourceType::Rest);
+            if (!isUserAddType)
+            {
+                throw CommandException(Resource::String::InvalidArgumentValueError(ArgumentCommon::ForType(Execution::Args::Type::SourceType).Name, Utility::Join(","_liv, validOptions)));
+            }
+        }
+
         if (execArgs.Contains(Execution::Args::Type::SourceTrustLevel))
         {
             try
diff --git a/src/AppInstallerCLICore/ConfigurationWingetDscModuleUnitValidation.cpp b/src/AppInstallerCLICore/ConfigurationWingetDscModuleUnitValidation.cpp
index 9455573983..8330143aeb 100644
--- a/src/AppInstallerCLICore/ConfigurationWingetDscModuleUnitValidation.cpp
+++ b/src/AppInstallerCLICore/ConfigurationWingetDscModuleUnitValidation.cpp
@@ -119,7 +119,7 @@ namespace AppInstaller::CLI::Configuration
             {
                 if (Utility::CaseInsensitiveEquals(wellKnownSource.Name, source.Name) &&
                     Utility::CaseInsensitiveEquals(wellKnownSource.Arg, source.Arg) &&
-                    Utility::CaseInsensitiveEquals(wellKnownSource.Type, source.Type))
+                    Utility::CaseInsensitiveEquals(Repository::SourceTypeEnumToString(wellKnownSource.Type), source.Type))
                 {
                     return true;
                 }
diff --git a/src/AppInstallerCLICore/PackageCollection.cpp b/src/AppInstallerCLICore/PackageCollection.cpp
index 5d7b3eafa8..d696799f18 100644
--- a/src/AppInstallerCLICore/PackageCollection.cpp
+++ b/src/AppInstallerCLICore/PackageCollection.cpp
@@ -127,7 +127,9 @@ namespace AppInstaller::CLI
                 sourceDetails.Identifier = Utility::LocIndString{ detailsNode[ss.PackagesJson_Source_Identifier].asString() };
                 sourceDetails.Name = detailsNode[ss.PackagesJson_Source_Name].asString();
                 sourceDetails.Arg = detailsNode[ss.PackagesJson_Source_Argument].asString();
-                sourceDetails.Type = detailsNode[ss.PackagesJson_Source_Type].asString();
+                auto sourceType = TryConvertToSourceTypeEnum(detailsNode[ss.PackagesJson_Source_Type].asString());
+                THROW_HR_IF(APPINSTALLER_CLI_ERROR_JSON_INVALID_FILE, !sourceType.has_value());
+                sourceDetails.Type = sourceType.value();
 
                 PackageCollection::Source source{ std::move(sourceDetails) };
                 for (const auto& packageNode : sourceNode[ss.PackagesJson_Packages])
@@ -238,7 +240,7 @@ namespace AppInstaller::CLI
             sourceDetailsNode[ss.PackagesJson_Source_Name] = source.Details.Name;
             sourceDetailsNode[ss.PackagesJson_Source_Argument] = source.Details.Arg;
             sourceDetailsNode[ss.PackagesJson_Source_Identifier] = source.Details.Identifier;
-            sourceDetailsNode[ss.PackagesJson_Source_Type] = source.Details.Type;
+            sourceDetailsNode[ss.PackagesJson_Source_Type] = std::string{ SourceTypeEnumToString(source.Details.Type) };
             sourceNode[ss.PackagesJson_Source_Details] = std::move(sourceDetailsNode);
 
             sourceNode[ss.PackagesJson_Packages] = Json::Value{ Json::ValueType::arrayValue };
diff --git a/src/AppInstallerCLICore/Workflows/ConfigurationFlow.cpp b/src/AppInstallerCLICore/Workflows/ConfigurationFlow.cpp
index 5cf513823a..084eb020b5 100644
--- a/src/AppInstallerCLICore/Workflows/ConfigurationFlow.cpp
+++ b/src/AppInstallerCLICore/Workflows/ConfigurationFlow.cpp
@@ -1495,7 +1495,7 @@ namespace AppInstaller::CLI::Workflow
 
         ConfigurationUnit CreateWinGetSourceUnit(const PackageCollection::Source& source, std::wstring_view unitType)
         {
-            std::string sourceUnitId = source.Details.Name + '_' + source.Details.Type;
+            std::string sourceUnitId = source.Details.Name + '_' + std::string{ Repository::SourceTypeEnumToString(source.Details.Type) };
             std::wstring sourceUnitIdWide = Utility::ConvertToUTF16(sourceUnitId);
 
             ConfigurationUnit unit;
@@ -1512,7 +1512,7 @@ namespace AppInstaller::CLI::Workflow
             ValueSet settings;
             settings.Insert(s_Setting_WinGetSource_Name, PropertyValue::CreateString(Utility::ConvertToUTF16(source.Details.Name)));
             settings.Insert(s_Setting_WinGetSource_Arg, PropertyValue::CreateString(Utility::ConvertToUTF16(source.Details.Arg)));
-            settings.Insert(s_Setting_WinGetSource_Type, PropertyValue::CreateString(Utility::ConvertToUTF16(source.Details.Type)));
+            settings.Insert(s_Setting_WinGetSource_Type, PropertyValue::CreateString(Utility::ConvertToUTF16(Repository::SourceTypeEnumToString(source.Details.Type))));
             if (WI_IsFlagSet(source.Details.TrustLevel, Repository::SourceTrustLevel::Trusted))
             {
                 settings.Insert(s_Setting_WinGetSource_TrustLevel, PropertyValue::CreateString(L"trusted"));
diff --git a/src/AppInstallerCLICore/Workflows/SourceFlow.cpp b/src/AppInstallerCLICore/Workflows/SourceFlow.cpp
index acccb9a421..d7b64be29b 100644
--- a/src/AppInstallerCLICore/Workflows/SourceFlow.cpp
+++ b/src/AppInstallerCLICore/Workflows/SourceFlow.cpp
@@ -50,7 +50,7 @@ namespace AppInstaller::CLI::Workflow
         auto sourceList = context.Get<Execution::Data::SourceList>();
         std::string_view name = context.Args.GetArg(Args::Type::SourceName);
         std::string_view arg = context.Args.GetArg(Args::Type::SourceArg);
-        std::string_view type = context.Args.GetArg(Args::Type::SourceType);
+        Repository::SourceType type = Repository::TryConvertToSourceTypeEnum(context.Args.GetArg(Args::Type::SourceType)).value_or(Repository::Source::GetDefaultSourceType());
 
         // In the absence of a specified type, the default is Microsoft.PreIndexed.Package for comparison.
         // The default type assignment to the source takes place during the add operation (Source::Add in Repository.cpp).
@@ -59,10 +59,6 @@ namespace AppInstaller::CLI::Workflow
         // For example, the following commands would be allowed, but they acts as different alias to same source:
         //      winget source add "mysource1" "https:\\mysource" --trust - level trusted
         //      winget source add "mysource2" "https:\\mysource" --trust - level trusted
-        if (type.empty())
-        {
-            type = Repository::Source::GetDefaultSourceType();
-        }
 
         for (const auto& details : sourceList)
         {
@@ -83,7 +79,7 @@ namespace AppInstaller::CLI::Workflow
                 }
             }
 
-            if (!details.Arg.empty() && details.Arg == arg && details.Type == type)
+            if (!details.Arg.empty() && details.Arg == arg && type == details.Type)
             {
                 context.Reporter.Error() << Resource::String::SourceAddAlreadyExistsDifferentName << std::endl <<
                     "  "_liv << details.Name << " -> "_liv << details.Arg << std::endl;
@@ -118,7 +114,7 @@ namespace AppInstaller::CLI::Workflow
         {
             std::string_view name = context.Args.GetArg(Args::Type::SourceName);
             std::string_view arg = context.Args.GetArg(Args::Type::SourceArg);
-            std::string_view type = context.Args.GetArg(Args::Type::SourceType);
+            Repository::SourceType type = Repository::TryConvertToSourceTypeEnum(context.Args.GetArg(Args::Type::SourceType)).value_or(Repository::Source::GetDefaultSourceType());
 
             Repository::SourceTrustLevel trustLevel = Repository::SourceTrustLevel::None;
             if (context.Args.Contains(Execution::Args::Type::SourceTrustLevel))
@@ -183,7 +179,7 @@ namespace AppInstaller::CLI::Workflow
             Execution::TableOutput<2> table(context.Reporter, { Resource::String::SourceListField, Resource::String::SourceListValue });
 
             table.OutputLine({ Resource::LocString(Resource::String::SourceListName), source.Name });
-            table.OutputLine({ Resource::LocString(Resource::String::SourceListType), source.Type });
+            table.OutputLine({ Resource::LocString(Resource::String::SourceListType), std::string{ Repository::SourceTypeEnumToString(source.Type) } });
             table.OutputLine({ Resource::LocString(Resource::String::SourceListArg), source.Arg });
             table.OutputLine({ Resource::LocString(Resource::String::SourceListData), source.Data });
             table.OutputLine({ Resource::LocString(Resource::String::SourceListIdentifier), source.Identifier });
@@ -401,7 +397,7 @@ namespace AppInstaller::CLI::Workflow
             {
                 SourceFromPolicy s;
                 s.Name = source.Name;
-                s.Type = source.Type;
+                s.Type = std::string{ Repository::SourceTypeEnumToString(source.Type) };
                 s.Arg = source.Arg;
                 s.Data = source.Data;
                 s.Identifier = source.Identifier;
diff --git a/src/AppInstallerCLITests/ARPChanges.cpp b/src/AppInstallerCLITests/ARPChanges.cpp
index 66b4481c05..f8da3215fe 100644
--- a/src/AppInstallerCLITests/ARPChanges.cpp
+++ b/src/AppInstallerCLITests/ARPChanges.cpp
@@ -102,7 +102,7 @@ struct ARPTestContext : public Context
         };
 
         // Inject our source
-        TestHook_SetSourceFactoryOverride(std::string{ Repository::Microsoft::PredefinedInstalledSourceFactory::Type() }, SourceFactory);
+        TestHook_SetSourceFactoryOverride(SourceType::PredefinedInstalled, SourceFactory);
 
         Source = std::make_shared<TestSource>();
         Source->SearchFunction = [&](const SearchRequest& request)
diff --git a/src/AppInstallerCLITests/CompositeSource.cpp b/src/AppInstallerCLITests/CompositeSource.cpp
index 8160c8df5e..cd1259adb6 100644
--- a/src/AppInstallerCLITests/CompositeSource.cpp
+++ b/src/AppInstallerCLITests/CompositeSource.cpp
@@ -330,7 +330,7 @@ struct CompositeWithTrackingTestSetup : public CompositeTestSetup
     CompositeWithTrackingTestSetup() : TrackingFactory([&](const SourceDetails&) { return Tracking; })
     {
         Tracking = std::make_shared<SQLiteIndexSource>(SourceDetails{}, SQLiteIndex::CreateNew(SQLITE_MEMORY_DB_CONNECTION_TARGET));
-        TestHook_SetSourceFactoryOverride(std::string{ PackageTrackingCatalogSourceFactory::Type() }, TrackingFactory);
+        TestHook_SetSourceFactoryOverride(SourceType::PackageTracking, TrackingFactory);
     }
 
     ~CompositeWithTrackingTestSetup()
diff --git a/src/AppInstallerCLITests/PackageCollection.cpp b/src/AppInstallerCLITests/PackageCollection.cpp
index 7a76c82578..2b7c68fb97 100644
--- a/src/AppInstallerCLITests/PackageCollection.cpp
+++ b/src/AppInstallerCLITests/PackageCollection.cpp
@@ -84,7 +84,7 @@ namespace
             const auto& jsonSourceDetails = GetAndValidateJsonProperty(*jsonSourceItr, s_PackagesJson_Source_Details, Json::ValueType::objectValue);
             ValidateJsonStringProperty(jsonSourceDetails, s_PackagesJson_Source_Name, sourceItr->Details.Name);
             ValidateJsonStringProperty(jsonSourceDetails, s_PackagesJson_Source_Argument, sourceItr->Details.Arg);
-            ValidateJsonStringProperty(jsonSourceDetails, s_PackagesJson_Source_Type, sourceItr->Details.Type);
+            ValidateJsonStringProperty(jsonSourceDetails, s_PackagesJson_Source_Type, SourceTypeEnumToString(sourceItr->Details.Type));
             ValidateJsonStringProperty(jsonSourceDetails, s_PackagesJson_Source_Identifier, sourceItr->Details.Identifier);
 
             const auto& jsonPackages = GetAndValidateJsonProperty(*jsonSourceItr, s_PackagesJson_Packages, Json::ValueType::arrayValue);
@@ -137,7 +137,7 @@ TEST_CASE("PackageCollection_Write_SingleSource", "[PackageCollection]")
     PackageCollection::Source source;
     source.Details.Name = "TestSource";
     source.Details.Arg = "https://aka.ms/winget";
-    source.Details.Type = "Microsoft.PreIndexed.Package";
+    source.Details.Type = SourceType::PreIndexedPackage;
     source.Details.Identifier = "TestSourceId";
 
     source.Packages.emplace_back(LocIndString{ "test.package1"sv }, Version{ "1.0.1" }, Channel{ "" });
@@ -157,14 +157,14 @@ TEST_CASE("PackageCollection_Write_MultipleSources", "[PackageCollection]")
     PackageCollection::Source source1;
     source1.Details.Name = "TestSource";
     source1.Details.Arg = "https://aka.ms/winget";
-    source1.Details.Type = "Microsoft.PreIndexed.Package";
+    source1.Details.Type = SourceType::PreIndexedPackage;
     source1.Details.Identifier = "TestSourceId";
     source1.Packages.emplace_back(LocIndString{ "test.package1"sv }, Version{ "1.0.1" }, Channel{ "" });
 
     PackageCollection::Source source2;
     source2.Details.Name = "TestSource2";
     source2.Details.Arg = "https://aka.ms/winget";
-    source2.Details.Type = "*Test";
+    source2.Details.Type = SourceType::ConfigurableTest;
     source2.Details.Identifier = "SecondId";
     source2.Packages.emplace_back(LocIndString{ "test.package2"sv }, Version{ "2.1.0" }, Channel{ "Beta" });
 
@@ -182,7 +182,7 @@ TEST_CASE("PackageCollection_Write_OverrideAndCustomSwitches", "[PackageCollecti
     PackageCollection::Source source;
     source.Details.Name = "TestSource";
     source.Details.Arg = "https://aka.ms/winget";
-    source.Details.Type = "Microsoft.PreIndexed.Package";
+    source.Details.Type = SourceType::PreIndexedPackage;
     source.Details.Identifier = "TestSourceId";
 
     PackageCollection::Package packageWithOverride{ LocIndString{ "test.withOverride"sv }, Version{ "1.0" }, Channel{ "" } };
@@ -246,7 +246,7 @@ TEST_CASE("PackageCollection_Read_SingleSource_1_0", "[PackageCollection]")
     PackageCollection::Source source;
     source.Details.Name = "TestSource";
     source.Details.Arg = "https://aka.ms/winget";
-    source.Details.Type = "Microsoft.PreIndexed.Package";
+    source.Details.Type = SourceType::PreIndexedPackage;
     source.Details.Identifier = "TestSourceId";
 
     source.Packages.emplace_back(LocIndString{ "test.WithVersion"sv }, Version{ "0.1" }, Channel{ "Preview" });
@@ -296,7 +296,7 @@ TEST_CASE("PackageCollection_Read_SingleSource_2_0", "[PackageCollection]")
     PackageCollection::Source source;
     source.Details.Name = "TestSource";
     source.Details.Arg = "https://aka.ms/winget";
-    source.Details.Type = "Microsoft.PreIndexed.Package";
+    source.Details.Type = SourceType::PreIndexedPackage;
     source.Details.Identifier = "TestSourceId";
 
     source.Packages.emplace_back(LocIndString{ "test.WithVersion"sv }, Version{ "0.1" }, Channel{ "Preview" });
@@ -378,7 +378,7 @@ TEST_CASE("PackageCollection_WriteRead_OverrideAndCustomSwitches", "[PackageColl
     PackageCollection::Source source;
     source.Details.Name = "TestSource";
     source.Details.Arg = "https://aka.ms/winget";
-    source.Details.Type = "Microsoft.PreIndexed.Package";
+    source.Details.Type = SourceType::PreIndexedPackage;
     source.Details.Identifier = "TestSourceId";
 
     PackageCollection::Package packageWithOverride{ LocIndString{ "test.withOverride"sv }, Version{ "1.0" }, Channel{ "" } };
@@ -437,7 +437,7 @@ TEST_CASE("PackageCollection_Read_MultipleSources_1_0", "[PackageCollection]")
             "Argument": "//secondSource",
             "Identifier": "Id2",
             "Name": "Second",
-            "Type": "*TestSource"
+            "Type": "Microsoft.Test.Configurable"
           },
           "Packages": [
             {
@@ -457,14 +457,14 @@ TEST_CASE("PackageCollection_Read_MultipleSources_1_0", "[PackageCollection]")
     PackageCollection::Source source1;
     source1.Details.Name = "First";
     source1.Details.Arg = "//firstSource";
-    source1.Details.Type = "Microsoft.PreIndexed.Package";
+    source1.Details.Type = SourceType::PreIndexedPackage;
     source1.Details.Identifier = "Id1";
     source1.Packages.emplace_back(LocIndString{ "test"sv }, Version{ "" }, Channel{ "" });
 
     PackageCollection::Source source2;
     source2.Details.Name = "Second";
     source2.Details.Arg = "//secondSource";
-    source2.Details.Type = "*TestSource";
+    source2.Details.Type = SourceType::ConfigurableTest;
     source2.Details.Identifier = "Id2";
     source2.Packages.emplace_back(LocIndString{ "test2"sv }, Version{ "1.0" }, Channel{ "" });
 
@@ -503,7 +503,7 @@ TEST_CASE("PackageCollection_Read_MultipleSources_2_0", "[PackageCollection]")
             "Argument": "//secondSource",
             "Identifier": "Id2",
             "Name": "Second",
-            "Type": "*TestSource"
+            "Type": "Microsoft.Test.Configurable"
           },
           "Packages": [
             {
@@ -523,14 +523,14 @@ TEST_CASE("PackageCollection_Read_MultipleSources_2_0", "[PackageCollection]")
     PackageCollection::Source source1;
     source1.Details.Name = "First";
     source1.Details.Arg = "//firstSource";
-    source1.Details.Type = "Microsoft.PreIndexed.Package";
+    source1.Details.Type = SourceType::PreIndexedPackage;
     source1.Details.Identifier = "Id1";
     source1.Packages.emplace_back(LocIndString{ "test"sv }, Version{ "" }, Channel{ "" });
 
     PackageCollection::Source source2;
     source2.Details.Name = "Second";
     source2.Details.Arg = "//secondSource";
-    source2.Details.Type = "*TestSource";
+    source2.Details.Type = SourceType::ConfigurableTest;
     source2.Details.Identifier = "Id2";
     source2.Packages.emplace_back(LocIndString{ "test2"sv }, Version{ "1.0" }, Channel{ "" });
 
@@ -569,7 +569,7 @@ TEST_CASE("PackageCollection_Read_RepeatedSource", "[PackageCollection]")
             "Argument": "//secondSource",
             "Identifier": "Id2",
             "Name": "Second",
-            "Type": "*TestSource"
+            "Type": "Microsoft.Test.Configurable"
           },
           "Packages": [
             {
@@ -583,7 +583,7 @@ TEST_CASE("PackageCollection_Read_RepeatedSource", "[PackageCollection]")
             "Argument": "//secondSource",
             "Identifier": "Id2",
             "Name": "Second",
-            "Type": "*TestSource"
+            "Type": "Microsoft.Test.Configurable"
           },
           "Packages": [
             {
@@ -603,14 +603,14 @@ TEST_CASE("PackageCollection_Read_RepeatedSource", "[PackageCollection]")
     PackageCollection::Source source1;
     source1.Details.Name = "First";
     source1.Details.Arg = "//firstSource";
-    source1.Details.Type = "Microsoft.PreIndexed.Package";
+    source1.Details.Type = SourceType::PreIndexedPackage;
     source1.Details.Identifier = "Id1";
     source1.Packages.emplace_back(LocIndString{ "test"sv }, Version{ "" }, Channel{ "" });
 
     PackageCollection::Source source2;
     source2.Details.Name = "Second";
     source2.Details.Arg = "//secondSource";
-    source2.Details.Type = "*TestSource";
+    source2.Details.Type = SourceType::ConfigurableTest;
     source2.Details.Identifier = "Id2";
     source2.Packages.emplace_back(LocIndString{ "test2"sv }, Version{ "1.0" }, Channel{ "" });
     source2.Packages.emplace_back(LocIndString{ "test3"sv }, Version{ "1.2" }, Channel{ "" });
diff --git a/src/AppInstallerCLITests/PackageTrackingCatalog.cpp b/src/AppInstallerCLITests/PackageTrackingCatalog.cpp
index d0a6354a1a..0b38079b5d 100644
--- a/src/AppInstallerCLITests/PackageTrackingCatalog.cpp
+++ b/src/AppInstallerCLITests/PackageTrackingCatalog.cpp
@@ -29,7 +29,7 @@ namespace
 
         details.Identifier = "*SimpleTestSetup";
         details.Name = "TestName";
-        details.Type = "TestType";
+        details.Type = SourceType::ConfigurableTest;
         details.Arg = testManifest.GetPath().parent_path().u8string();
         details.Data = "";
 
diff --git a/src/AppInstallerCLITests/PreIndexedPackageSource.cpp b/src/AppInstallerCLITests/PreIndexedPackageSource.cpp
index fe36dd1b31..653c14d3a3 100644
--- a/src/AppInstallerCLITests/PreIndexedPackageSource.cpp
+++ b/src/AppInstallerCLITests/PreIndexedPackageSource.cpp
@@ -79,7 +79,7 @@ TEST_CASE("PIPS_Add", "[pips]")
 
     SourceDetails details;
     details.Name = "TestName";
-    details.Type = AppInstaller::Repository::Microsoft::PreIndexedPackageSourceFactory::Type();
+    details.Type = AppInstaller::Repository::SourceType::PreIndexedPackage;
     details.Arg = dir;
     ProgressCallback callback;
 
@@ -117,7 +117,7 @@ TEST_CASE("PIPS_UpdateSameVersion", "[pips]")
 
     SourceDetails details;
     details.Name = "TestName";
-    details.Type = AppInstaller::Repository::Microsoft::PreIndexedPackageSourceFactory::Type();
+    details.Type = AppInstaller::Repository::SourceType::PreIndexedPackage;
     details.Arg = dir;
     TestProgress callback;
 
@@ -156,7 +156,7 @@ TEST_CASE("PIPS_UpdateNewVersion", "[pips]")
 
     SourceDetails details;
     details.Name = "TestName";
-    details.Type = AppInstaller::Repository::Microsoft::PreIndexedPackageSourceFactory::Type();
+    details.Type = AppInstaller::Repository::SourceType::PreIndexedPackage;
     details.Arg = dir;
     TestProgress callback;
 
@@ -205,7 +205,7 @@ TEST_CASE("PIPS_Remove", "[pips]")
 
     SourceDetails details;
     details.Name = "TestName";
-    details.Type = AppInstaller::Repository::Microsoft::PreIndexedPackageSourceFactory::Type();
+    details.Type = AppInstaller::Repository::SourceType::PreIndexedPackage;
     details.Arg = dir;
     ProgressCallback callback;
 
diff --git a/src/AppInstallerCLITests/PredefinedInstalledSource.cpp b/src/AppInstallerCLITests/PredefinedInstalledSource.cpp
index 4939f99cda..6e41f6d398 100644
--- a/src/AppInstallerCLITests/PredefinedInstalledSource.cpp
+++ b/src/AppInstallerCLITests/PredefinedInstalledSource.cpp
@@ -138,7 +138,7 @@ void VerifyEntryAgainstIndex(const SQLiteIndex& index, SQLiteIndex::IdType manif
 std::shared_ptr<ISource> CreatePredefinedInstalledSource(Factory::Filter filter = Factory::Filter::None)
 {
     SourceDetails details;
-    details.Type = Factory::Type();
+    details.Type = AppInstaller::Repository::SourceType::PredefinedInstalled;
     details.Arg = Factory::FilterToString(filter);
 
     TestProgress progress;
diff --git a/src/AppInstallerCLITests/SQLiteIndexSource.cpp b/src/AppInstallerCLITests/SQLiteIndexSource.cpp
index 296d0f2c0b..9190e9ee32 100644
--- a/src/AppInstallerCLITests/SQLiteIndexSource.cpp
+++ b/src/AppInstallerCLITests/SQLiteIndexSource.cpp
@@ -38,7 +38,7 @@ static std::shared_ptr<SQLiteIndexSource> SimpleTestSetup(const std::string& fil
     index.AddManifest(manifest, relativePath);
 
     details.Name = "TestName";
-    details.Type = "TestType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = sourceFilesDirectoryPath.u8string();
     details.Data = "";
     details.Identifier = "SimpleTestSetup";
diff --git a/src/AppInstallerCLITests/SourceFlow.cpp b/src/AppInstallerCLITests/SourceFlow.cpp
index 1bea3bbc92..3852840ad8 100644
--- a/src/AppInstallerCLITests/SourceFlow.cpp
+++ b/src/AppInstallerCLITests/SourceFlow.cpp
@@ -45,7 +45,7 @@ TEST_CASE("SourceAddFlow_Agreement", "[SourceAddFlow][workflow]")
     auto previousThreadGlobals = context.SetForCurrentThread();
     OverrideForSourceAddWithAgreements(context);
     context.Args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
-    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Test"sv);
+    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Rest"sv);
     context.Args.AddArg(Execution::Args::Type::SourceArg, "TestArg"sv);
     context.Args.AddArg(Execution::Args::Type::AcceptSourceAgreements);
 
@@ -72,7 +72,7 @@ TEST_CASE("SourceAddFlow_Agreement_Prompt_Yes", "[SourceAddFlow][workflow]")
     auto previousThreadGlobals = context.SetForCurrentThread();
     OverrideForSourceAddWithAgreements(context);
     context.Args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
-    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Test"sv);
+    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Rest"sv);
     context.Args.AddArg(Execution::Args::Type::SourceArg, "TestArg"sv);
 
     SourceAddCommand sourceAdd({});
@@ -98,7 +98,7 @@ TEST_CASE("SourceAddFlow_Agreement_Prompt_No", "[SourceAddFlow][workflow]")
     auto previousThreadGlobals = context.SetForCurrentThread();
     OverrideForSourceAddWithAgreements(context, false);
     context.Args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
-    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Test"sv);
+    context.Args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Rest"sv);
     context.Args.AddArg(Execution::Args::Type::SourceArg, "TestArg"sv);
 
     SourceAddCommand sourceAdd({});
@@ -115,6 +115,39 @@ TEST_CASE("SourceAddFlow_Agreement_Prompt_No", "[SourceAddFlow][workflow]")
     REQUIRE(context.GetTerminationHR() == APPINSTALLER_CLI_ERROR_SOURCE_AGREEMENTS_NOT_ACCEPTED);
 }
 
+TEST_CASE("SourceAddCommand_ValidateArguments_SourceType", "[SourceAddFlow][workflow]")
+{
+    SourceAddCommand sourceAdd({});
+
+    SECTION("Valid external source type")
+    {
+        Execution::Args args;
+        args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
+        args.AddArg(Execution::Args::Type::SourceArg, "https://testsource.invalid"sv);
+        args.AddArg(Execution::Args::Type::SourceType, "microsoft.rest"sv);
+
+        REQUIRE_NOTHROW(sourceAdd.ValidateArguments(args));
+    }
+
+    SECTION("Invalid source type")
+    {
+        Execution::Args args;
+        args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
+        args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Unknown"sv);
+
+        REQUIRE_THROWS(sourceAdd.ValidateArguments(args));
+    }
+
+    SECTION("Internal source type not accepted by source add")
+    {
+        Execution::Args args;
+        args.AddArg(Execution::Args::Type::SourceName, "TestSource"sv);
+        args.AddArg(Execution::Args::Type::SourceType, "Microsoft.Predefined.Installed"sv);
+
+        REQUIRE_THROWS(sourceAdd.ValidateArguments(args));
+    }
+}
+
 TEST_CASE("OpenSource_WithCustomHeader", "[OpenSource][CustomHeader]")
 {
     SetSetting(Stream::UserSources, R"(Sources:)"sv);
@@ -122,7 +155,7 @@ TEST_CASE("OpenSource_WithCustomHeader", "[OpenSource][CustomHeader]")
 
     SourceDetails details;
     details.Name = "restsource";
-    details.Type = "Microsoft.Rest";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
 
diff --git a/src/AppInstallerCLITests/Sources.cpp b/src/AppInstallerCLITests/Sources.cpp
index 730dfa02f2..8bb50c2d72 100644
--- a/src/AppInstallerCLITests/Sources.cpp
+++ b/src/AppInstallerCLITests/Sources.cpp
@@ -60,7 +60,7 @@ constexpr std::string_view s_DefaultSourcesTombstoned = R"(
 constexpr std::string_view s_SingleSource = R"(
 Sources:
   - Name: testName
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
@@ -114,12 +114,12 @@ constexpr std::string_view s_SingleSourceMetadataUpdate = R"(
 constexpr std::string_view s_DoubleSource = R"(
 Sources:
   - Name: testName
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
   - Name: testName2
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg2
     Data: testData2
     IsTombstone: false
@@ -136,19 +136,19 @@ constexpr std::string_view s_DoubleSourceMetadata = R"(
 constexpr std::string_view s_ThreeSources = R"(
 Sources:
   - Name: testName
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
     Priority: 1
   - Name: testName2
-    Type: testType2
+    Type: Microsoft.Test.Configurable
     Arg: testArg2
     Data: testData2
     IsTombstone: false
     Priority: 5
   - Name: testName3
-    Type: testType3
+    Type: Microsoft.Test.Configurable
     Arg: testArg3
     Data: testData3
     IsTombstone: false
@@ -183,7 +183,7 @@ constexpr std::string_view s_ThreeSourcesMetadata = R"(
 constexpr std::string_view s_SingleSource_MissingArg = R"(
 Sources:
   - Name: testName
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Data: testData
     IsTombstone: false
 )"sv;
@@ -191,12 +191,12 @@ constexpr std::string_view s_SingleSource_MissingArg = R"(
 constexpr std::string_view s_TwoSource_AggregateSourceTest = R"(
 Sources:
   - Name: winget
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
   - Name: msstore
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
@@ -214,7 +214,7 @@ constexpr std::string_view s_DefaultSourceAsUserSource = R"(
 constexpr std::string_view s_UserSourceNamedLikeDefault = R"(
 Sources:
   - Name: winget
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
@@ -223,7 +223,7 @@ constexpr std::string_view s_UserSourceNamedLikeDefault = R"(
 constexpr std::string_view s_SingleSource_AllProperties= R"(
 Sources:
   - Name: testName
-    Type: testType
+    Type: Microsoft.Test.Configurable
     Arg: testArg
     Data: testData
     IsTombstone: false
@@ -340,7 +340,7 @@ TEST_CASE("RepoSources_DefaultSourceOverride", "[sources]")
     REQUIRE(beforeOverride[2].Name == "winget-font");
     REQUIRE(beforeOverride[2].Arg == "https://cdn.winget.microsoft.com/fonts");
     REQUIRE(beforeOverride[2].Data == "Microsoft.Winget.Fonts.Source_8wekyb3d8bbwe");
-    REQUIRE(beforeOverride[2].Type == "Microsoft.PreIndexed.Package");
+    REQUIRE(beforeOverride[2].Type == SourceType::PreIndexedPackage);
     REQUIRE(beforeOverride[2].Origin == SourceOrigin::Default);
     REQUIRE(beforeOverride[2].Explicit == true);
     REQUIRE(beforeOverride[2].Priority == 0);
@@ -373,7 +373,7 @@ TEST_CASE("RepoSources_SingleSource", "[sources]")
     REQUIRE(sources.size() == c_DefaultSourceCount + 1);
 
     REQUIRE(sources[0].Name == "testName");
-    REQUIRE(sources[0].Type == "testType");
+    REQUIRE(sources[0].Type == SourceType::ConfigurableTest);
     REQUIRE(sources[0].Arg == "testArg");
     REQUIRE(sources[0].Data == "testData");
     REQUIRE(sources[0].Origin == SourceOrigin::User);
@@ -391,7 +391,7 @@ TEST_CASE("RepoSources_SingleSource_AllProperties", "[sources]")
     REQUIRE(sources.size() == c_DefaultSourceCount + 1);
 
     REQUIRE(sources[0].Name == "testName");
-    REQUIRE(sources[0].Type == "testType");
+    REQUIRE(sources[0].Type == SourceType::ConfigurableTest);
     REQUIRE(sources[0].Arg == "testArg");
     REQUIRE(sources[0].Data == "testData");
     REQUIRE(sources[0].Origin == SourceOrigin::User);
@@ -434,7 +434,7 @@ TEST_CASE("RepoSources_ThreeSources", "[sources]")
 
         INFO("Source #" << index << " [" << i << "]");
         REQUIRE(sources[index].Name == "testName"s + suffixStrings[i]);
-        REQUIRE(sources[index].Type == "testType"s + suffixStrings[i]);
+        REQUIRE(sources[index].Type == SourceType::ConfigurableTest);
         REQUIRE(sources[index].Arg == "testArg"s + suffixStrings[i]);
         REQUIRE(sources[index].Data == "testData"s + suffixStrings[i]);
         REQUIRE(sources[index].LastUpdateTime == ConvertUnixEpochToSystemClock(i));
@@ -463,7 +463,7 @@ TEST_CASE("RepoSources_AddSource", "[sources]")
 
     SourceDetails details;
     details.Name = "thisIsTheName";
-    details.Type = "thisIsTheType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
     details.TrustLevel = Repository::SourceTrustLevel::None;
@@ -502,7 +502,7 @@ TEST_CASE("RepoSources_AddMultipleSources", "[sources]")
 
     SourceDetails details;
     details.Name = "thisIsTheName";
-    details.Type = "thisIsTheType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
 
@@ -529,7 +529,7 @@ TEST_CASE("RepoSources_AddMultipleSources", "[sources]")
 
     SourceDetails details2;
     details2.Name = details.Name + suffix[1];
-    details2.Type = details.Type + suffix[1];
+    details2.Type = details.Type;
     details2.Arg = details.Arg + suffix[1];
     details2.Data = details.Data + suffix[1];
     TestSourceFactory factory2{ SourcesTestSource::Create };
@@ -545,7 +545,7 @@ TEST_CASE("RepoSources_AddMultipleSources", "[sources]")
     {
         INFO("Source #" << i);
         REQUIRE(sources[i].Name == details.Name + suffix[i]);
-        REQUIRE(sources[i].Type == details.Type + suffix[i]);
+        REQUIRE(sources[i].Type == details.Type);
         REQUIRE(sources[i].Arg == details.Arg + suffix[i]);
         REQUIRE(sources[i].Data == details.Data + suffix[i]);
         REQUIRE(sources[i].LastUpdateTime != ConvertUnixEpochToSystemClock(0));
@@ -564,7 +564,7 @@ TEST_CASE("RepoSources_UpdateSource", "[sources]")
 
     SourceDetails details;
     details.Name = "thisIsTheName";
-    details.Type = "thisIsTheType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
 
@@ -618,7 +618,7 @@ TEST_CASE("RepoSources_UpdateSourceRetries", "[sources]")
 
     SourceDetails details;
     details.Name = "thisIsTheName";
-    details.Type = "thisIsTheType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
 
@@ -654,7 +654,7 @@ TEST_CASE("RepoSources_RemoveSource", "[sources]")
 
     SourceDetails details;
     details.Name = "thisIsTheName";
-    details.Type = "thisIsTheType";
+    details.Type = SourceType::ConfigurableTest;
     details.Arg = "thisIsTheArg";
     details.Data = "thisIsTheData";
 
@@ -708,7 +708,7 @@ TEST_CASE("RepoSources_UpdateOnOpen", "[sources]")
     TestHook_ClearSourceFactoryOverrides();
 
     std::string name = "testName";
-    std::string type = "testType";
+    SourceType type = SourceType::ConfigurableTest;
     std::string arg = "testArg";
     std::string data = "testData";
 
@@ -754,7 +754,7 @@ TEST_CASE("RepoSources_DropSourceByName", "[sources]")
     {
         INFO("Source #" << i);
         REQUIRE(sources[i].Name == "testName"s + suffix[i]);
-        REQUIRE(sources[i].Type == "testType"s + suffix[i]);
+        REQUIRE(sources[i].Type == SourceType::ConfigurableTest);
         REQUIRE(sources[i].Arg == "testArg"s + suffix[i]);
         REQUIRE(sources[i].Data == "testData"s + suffix[i]);
         REQUIRE(sources[i].LastUpdateTime == ConvertUnixEpochToSystemClock(i + 1));
@@ -855,7 +855,7 @@ TEST_CASE("RepoSources_SearchAcrossMultipleSources", "[sources]")
 {
     TestHook_ClearSourceFactoryOverrides();
     TestSourceFactory factory{ SourcesTestSource::Create };
-    TestHook_SetSourceFactoryOverride("testType", factory);
+    TestHook_SetSourceFactoryOverride(SourceType::ConfigurableTest, factory);
 
     SetSetting(Stream::UserSources, s_TwoSource_AggregateSourceTest);
 
@@ -908,7 +908,7 @@ TEST_CASE("RepoSources_GroupPolicy_DefaultSource", "[sources][groupPolicy]")
             ProgressCallback progress;
             SourceDetails details;
             details.Name = "winget";
-            details.Type = "Microsoft.PreIndexed.Package";
+            details.Type = SourceType::PreIndexedPackage;
             details.Arg = "https://cdn.winget.microsoft.com/cache";
             REQUIRE_POLICY_EXCEPTION(
                 AddSource(details, progress),
@@ -931,7 +931,7 @@ TEST_CASE("RepoSources_GroupPolicy_DefaultSource", "[sources][groupPolicy]")
 
             SourceDetails details;
             details.Name = "winget";
-            details.Type = "someType";
+            details.Type = SourceType::ConfigurableTest;
             details.Arg = "notWingetRealArg";
             details.Data = "someData";
 
@@ -965,7 +965,7 @@ TEST_CASE("RepoSources_GroupPolicy_DefaultSource", "[sources][groupPolicy]")
             REQUIRE(sources.size() == c_DefaultSourceCount);
 
             REQUIRE(sources[0].Name == "winget");
-            REQUIRE(sources[0].Type == "testType");
+            REQUIRE(sources[0].Type == SourceType::ConfigurableTest);
             REQUIRE(sources[0].Arg == "testArg");
             REQUIRE(sources[0].Data == "testData");
             REQUIRE(sources[0].Origin == SourceOrigin::User);
@@ -1028,7 +1028,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             {
                 SourceFromPolicy source;
                 source.Name = "name" + suffix[i];
-                source.Type = "type" + suffix[i];
+                source.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
                 source.Arg = "arg" + suffix[i];
                 source.Data = "data" + suffix[i];
                 source.Identifier = "id" + suffix[i];
@@ -1047,7 +1047,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             for (size_t i = 0; i < policySources.size(); ++i)
             {
                 REQUIRE(sources[i].Name == policySources[i].Name);
-                REQUIRE(sources[i].Type == policySources[i].Type);
+                REQUIRE(SourceTypeEnumToString(sources[i].Type) == policySources[i].Type);
                 REQUIRE(sources[i].Arg == policySources[i].Arg);
                 REQUIRE(sources[i].Data == policySources[i].Data);
                 REQUIRE(sources[i].Identifier == policySources[i].Identifier);
@@ -1059,7 +1059,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             // User sources with the same name as an additional source are ignored.
             SourceFromPolicy policySource;
             policySource.Name = "testName";
-            policySource.Type = "notTestType";
+            policySource.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
             policySource.Arg = "notTestArg";
             policySource.Data = "notTestData";
             policySource.Identifier = "notTestId";
@@ -1074,7 +1074,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             REQUIRE(sources[1].Origin == SourceOrigin::Default);
 
             REQUIRE(sources[0].Name == policySource.Name);
-            REQUIRE(sources[0].Type == policySource.Type);
+            REQUIRE(SourceTypeEnumToString(sources[0].Type) == policySource.Type);
             REQUIRE(sources[0].Arg == policySource.Arg);
             REQUIRE(sources[0].Data == policySource.Data);
             REQUIRE(sources[0].Identifier == policySource.Identifier);
@@ -1085,7 +1085,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             // An additional source cannot be removed.
             SourceFromPolicy policySource;
             policySource.Name = "name";
-            policySource.Type = "type";
+            policySource.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
             policySource.Arg = "arg";
             policySource.Data = "data";
             policySource.Identifier = "id";
@@ -1093,7 +1093,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             bool removeCalledOnFactory = false;
             TestSourceFactory factory{ SourcesTestSource::Create };
             factory.OnRemove = [&](const SourceDetails&) { removeCalledOnFactory = true; };
-            TestHook_SetSourceFactoryOverride(policySource.Type, factory);
+            TestHook_SetSourceFactoryOverride(ConvertToSourceTypeEnum(policySource.Type), factory);
 
             policies.SetValue<ValuePolicy::AdditionalSources>({ policySource });
             SetSetting(Stream::UserSources, s_EmptySources);
@@ -1109,7 +1109,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
             // An additional source with the same name as a default overrides it.
             SourceFromPolicy policySource;
             policySource.Name = "winget";
-            policySource.Type = "notDefaultType";
+            policySource.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
             policySource.Arg = "notDefaultArg";
             policySource.Data = "notDefaultData";
             policySource.Identifier = "notDefaultId";
@@ -1121,7 +1121,7 @@ TEST_CASE("RepoSources_GroupPolicy_AdditionalSources", "[sources][groupPolicy]")
 
             REQUIRE(sources.size() == c_DefaultSourceCount);
             REQUIRE(sources[0].Name == policySource.Name);
-            REQUIRE(sources[0].Type == policySource.Type);
+            REQUIRE(SourceTypeEnumToString(sources[0].Type) == policySource.Type);
             REQUIRE(sources[0].Arg == policySource.Arg);
             REQUIRE(sources[0].Data == policySource.Data);
             REQUIRE(sources[0].Identifier == policySource.Identifier);
@@ -1142,7 +1142,7 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
             // We should be able to add sources in the allow list.
             SourceFromPolicy policySource;
             policySource.Name = "testName";
-            policySource.Type = "testType";
+            policySource.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
             policySource.Arg = "testArg";
             policySource.Data = "testData";
             policySource.Identifier = "testId";
@@ -1159,12 +1159,12 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
                 sd.Data = policySource.Data;
                 sd.Identifier = policySource.Identifier;
             };
-            TestHook_SetSourceFactoryOverride(policySource.Type, factory);
+            TestHook_SetSourceFactoryOverride(ConvertToSourceTypeEnum(policySource.Type), factory);
 
             ProgressCallback progress;
             SourceDetails details;
             details.Name = policySource.Name;
-            details.Type = policySource.Type;
+            details.Type = SourceType::ConfigurableTest;
             details.Arg = policySource.Arg;
             AddSource(details, progress);
 
@@ -1176,7 +1176,7 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
             REQUIRE(sources[1].Origin == SourceOrigin::Default);
 
             REQUIRE(sources[0].Name == policySource.Name);
-            REQUIRE(sources[0].Type == policySource.Type);
+            REQUIRE(SourceTypeEnumToString(sources[0].Type) == policySource.Type);
             REQUIRE(sources[0].Arg == policySource.Arg);
             REQUIRE(sources[0].Data == policySource.Data);
             REQUIRE(sources[0].Identifier == policySource.Identifier);
@@ -1187,7 +1187,7 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
             // We should not be allowed to add anything not matching the allow list.
             SourceFromPolicy policySource;
             policySource.Name = "testName";
-            policySource.Type = "testType";
+            policySource.Type = std::string{ SourceTypeEnumToString(SourceType::ConfigurableTest) };
             policySource.Arg = "testArg";
             policySource.Data = "testData";
             policySource.Identifier = "testId";
@@ -1198,7 +1198,7 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
             ProgressCallback progress;
             SourceDetails details;
             details.Name = "notAllowed";
-            details.Type = "type";
+            details.Type = SourceType::ConfigurableTest;
             details.Arg = "arg";
 
             bool addCalledOnFactory = false;
@@ -1225,7 +1225,7 @@ TEST_CASE("RepoSources_GroupPolicy_AllowedSources", "[sources][groupPolicy]")
             ProgressCallback progress;
             SourceDetails details;
             details.Name = "name";
-            details.Type = "type";
+            details.Type = SourceType::ConfigurableTest;
             details.Arg = "arg";
 
             bool addCalledOnFactory = false;
@@ -1257,7 +1257,7 @@ TEST_CASE("RepoSources_OpenMultipleWithSingleFailure", "[sources]")
 {
     TestHook_ClearSourceFactoryOverrides();
     TestSourceFactory factory{ FailingSourcesTestSource::CreateFailWinget };
-    TestHook_SetSourceFactoryOverride("testType", factory);
+    TestHook_SetSourceFactoryOverride(SourceType::ConfigurableTest, factory);
 
     SetSetting(Stream::UserSources, s_TwoSource_AggregateSourceTest);
 
@@ -1288,7 +1288,7 @@ TEST_CASE("RepoSources_OpenMultipleWithTotalFailure", "[sources]")
 {
     TestHook_ClearSourceFactoryOverrides();
     TestSourceFactory factory{ FailingSourcesTestSource::CreateFailAll };
-    TestHook_SetSourceFactoryOverride("testType", factory);
+    TestHook_SetSourceFactoryOverride(SourceType::ConfigurableTest, factory);
 
     SetSetting(Stream::UserSources, s_TwoSource_AggregateSourceTest);
 
@@ -1309,7 +1309,7 @@ TEST_CASE("RepoSources_UpdateSettingsDuringAction_SourcesUpdate", "[sources]")
 
     std::string unusedSourceName = "unusedName";
     std::string unusedSourceArg = "unusedArg";
-    std::string testSourceType = "testType";
+    SourceType testSourceType = SourceType::ConfigurableTest;
 
     TestHook_ClearSourceFactoryOverrides();
     TestSourceFactory factory{ FailingSourcesTestSource::CreateFailAll };
@@ -1392,7 +1392,7 @@ TEST_CASE("RepoSources_UpdateSettingsDuringAction_MetadataUpdate", "[sources]")
 
     std::string unusedSourceName = "unusedName";
     std::string unusedSourceArg = "unusedArg";
-    std::string testSourceType = "testType";
+    SourceType testSourceType = SourceType::ConfigurableTest;
 
     TestHook_ClearSourceFactoryOverrides();
     TestSourceFactory factory{ FailingSourcesTestSource::CreateFailAll };
@@ -1462,7 +1462,12 @@ TEST_CASE("RepoSources_RestoringWellKnownSource", "[sources]")
 
     SECTION("with well known name")
     {
-        Source addStoreBack{ details.Name, details.Arg, details.Type, Repository::SourceTrustLevel::None, {} };
+        Source addStoreBack{
+            details.Name,
+            details.Arg,
+            details.Type,
+            Repository::SourceTrustLevel::None,
+            {} };
         REQUIRE(addStoreBack.Add(progress));
 
         Source storeAfterAdd{ details.Name };
@@ -1473,7 +1478,12 @@ TEST_CASE("RepoSources_RestoringWellKnownSource", "[sources]")
     SECTION("with different name")
     {
         std::string newName = details.Name + "_new";
-        Source addStoreBack{ newName, details.Arg, details.Type, Repository::SourceTrustLevel::None, {} };
+        Source addStoreBack{
+            newName,
+            details.Arg,
+            details.Type,
+            Repository::SourceTrustLevel::None,
+            {} };
         REQUIRE(addStoreBack.Add(progress));
 
         Source storeAfterAdd{ newName };
@@ -1537,3 +1547,24 @@ TEST_CASE("RepoSources_MicrosoftStore_CertificatePinningLifetimeCheck", "[source
     double lifetimePercentage = source.GetDetails().CertificatePinningConfiguration.GetRemainingLifetimePercentage();
     REQUIRE(lifetimePercentage > 0.25);
 }
+
+TEST_CASE("RepoSources_SourceTypeEnumConversion", "[sources]")
+{
+    REQUIRE(ConvertToSourceTypeEnum("Microsoft.PreIndexed.Package"sv) == SourceType::PreIndexedPackage);
+    REQUIRE(ConvertToSourceTypeEnum("microsoft.rest"sv) == SourceType::Rest);
+    REQUIRE(ConvertToSourceTypeEnum("Microsoft.Predefined.Installed"sv) == SourceType::PredefinedInstalled);
+    REQUIRE(ConvertToSourceTypeEnum("Microsoft.Predefined.Writeable"sv) == SourceType::PredefinedWriteable);
+    REQUIRE(ConvertToSourceTypeEnum("Microsoft.PackageTracking"sv) == SourceType::PackageTracking);
+#ifndef AICLI_DISABLE_TEST_HOOKS
+    REQUIRE(ConvertToSourceTypeEnum("Microsoft.Test.Configurable"sv) == SourceType::ConfigurableTest);
+#endif
+
+    REQUIRE(TryConvertToSourceTypeEnum("Microsoft.Unknown"sv) == std::nullopt);
+    REQUIRE_THROWS_HR(ConvertToSourceTypeEnum("Microsoft.Unknown"sv), APPINSTALLER_CLI_ERROR_INVALID_SOURCE_TYPE);
+
+    REQUIRE(TryConvertToSourceTypeEnum(""sv).value_or(Source::GetDefaultSourceType()) == Source::GetDefaultSourceType());
+    REQUIRE(SourceTypeEnumToString(SourceType::PreIndexedPackage) == "Microsoft.PreIndexed.Package"sv);
+    REQUIRE(SourceTypeEnumToString(SourceType::Rest) == "Microsoft.Rest"sv);
+    REQUIRE(Source::GetDefaultSourceType() == SourceType::PreIndexedPackage);
+    REQUIRE(SourceTypeEnumToString(Source::GetDefaultSourceType()) == "Microsoft.PreIndexed.Package"sv);
+}
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackage.json b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackage.json
index 7c22a36dd3..631768531e 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackage.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackage.json
@@ -17,7 +17,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackageVersion.json b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackageVersion.json
index ebc0626b1f..80d3099e7d 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackageVersion.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownPackageVersion.json
@@ -13,7 +13,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownSource.json b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownSource.json
index 7d66f87f98..5fd78f6d62 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownSource.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Bad-UnknownSource.json
@@ -13,7 +13,7 @@
         "Argument": "//bad",
         "Identifier": "*BadSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-AlreadyInstalled.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-AlreadyInstalled.json
index 137c2d9366..ebdbddd0ba 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-AlreadyInstalled.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-AlreadyInstalled.json
@@ -13,7 +13,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-Dependencies.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-Dependencies.json
index e1e1a5ac1a..0c9c7f073e 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-Dependencies.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-Dependencies.json
@@ -17,7 +17,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-MachineScope.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-MachineScope.json
index a80b455e47..0a95371140 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-MachineScope.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-MachineScope.json
@@ -14,7 +14,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithCustomSwitches.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithCustomSwitches.json
index 5271e795be..702b79a0d1 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithCustomSwitches.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithCustomSwitches.json
@@ -13,7 +13,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithLicenseAgreement.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithLicenseAgreement.json
index e035111554..5530376f79 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithLicenseAgreement.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithLicenseAgreement.json
@@ -13,7 +13,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithOverrideArgs.json b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithOverrideArgs.json
index 6f5309d556..5b1b5e8ad1 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good-WithOverrideArgs.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good-WithOverrideArgs.json
@@ -13,7 +13,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestData/ImportFile-Good.json b/src/AppInstallerCLITests/TestData/ImportFile-Good.json
index de132544e6..a154cb5c50 100644
--- a/src/AppInstallerCLITests/TestData/ImportFile-Good.json
+++ b/src/AppInstallerCLITests/TestData/ImportFile-Good.json
@@ -17,7 +17,7 @@
         "Argument": "//arg",
         "Identifier": "*TestSource",
         "Name": "TestSource",
-        "Type": "Microsoft.TestSource"
+        "Type": "Microsoft.Test.Configurable"
       }
     }
   ],
diff --git a/src/AppInstallerCLITests/TestHooks.h b/src/AppInstallerCLITests/TestHooks.h
index 8c976a1381..e1617ae543 100644
--- a/src/AppInstallerCLITests/TestHooks.h
+++ b/src/AppInstallerCLITests/TestHooks.h
@@ -38,7 +38,7 @@ namespace AppInstaller
 
     namespace Repository
     {
-        void TestHook_SetSourceFactoryOverride(const std::string& type, std::function<std::unique_ptr<ISourceFactory>()>&& factory);
+        void TestHook_SetSourceFactoryOverride(SourceType type, std::function<std::unique_ptr<ISourceFactory>()>&& factory);
         void TestHook_ClearSourceFactoryOverrides();
         void TestHook_SetExtractIconFromArpEntryResult_Override(std::vector<AppInstaller::Repository::ExtractedIconInfo>* result);
     }
diff --git a/src/AppInstallerCLITests/TestSource.cpp b/src/AppInstallerCLITests/TestSource.cpp
index f864b95a98..18f4bd20f4 100644
--- a/src/AppInstallerCLITests/TestSource.cpp
+++ b/src/AppInstallerCLITests/TestSource.cpp
@@ -492,7 +492,12 @@ namespace TestCommon
         Repository::SourceEdit additionalProperties;
         additionalProperties.Explicit = details.Explicit;
         additionalProperties.Priority = details.Priority;
-        Repository::Source source{ details.Name, details.Arg, details.Type, Repository::SourceTrustLevel::None, additionalProperties };
+        Repository::Source source{
+            details.Name,
+            details.Arg,
+            details.Type,
+            Repository::SourceTrustLevel::None,
+            additionalProperties };
         return source.Add(progress);
     }
 
diff --git a/src/AppInstallerCLITests/TestSource.h b/src/AppInstallerCLITests/TestSource.h
index c6ced92427..a4af9fa1de 100644
--- a/src/AppInstallerCLITests/TestSource.h
+++ b/src/AppInstallerCLITests/TestSource.h
@@ -128,7 +128,7 @@ namespace TestCommon
         AppInstaller::Repository::SearchResult Search(const AppInstaller::Repository::SearchRequest& request) const override;
         void* CastTo(AppInstaller::Repository::ISourceType type) override;
 
-        AppInstaller::Repository::SourceDetails Details = { "TestSource", "Microsoft.TestSource", "//arg", "", "*TestSource" };
+        AppInstaller::Repository::SourceDetails Details = { "TestSource", AppInstaller::Repository::SourceType::ConfigurableTest, "//arg", "", "*TestSource" };
         AppInstaller::Repository::SourceInformation Information;
         std::function<AppInstaller::Repository::SearchResult(const AppInstaller::Repository::SearchRequest& request)> SearchFunction;
 
diff --git a/src/AppInstallerRepositoryCore/Microsoft/PreIndexedPackageSourceFactory.cpp b/src/AppInstallerRepositoryCore/Microsoft/PreIndexedPackageSourceFactory.cpp
index 53a73e1835..549fa3afcf 100644
--- a/src/AppInstallerRepositoryCore/Microsoft/PreIndexedPackageSourceFactory.cpp
+++ b/src/AppInstallerRepositoryCore/Microsoft/PreIndexedPackageSourceFactory.cpp
@@ -199,8 +199,7 @@ namespace AppInstaller::Repository::Microsoft
 
             std::shared_ptr<ISourceReference> Create(const SourceDetails& details) override final
             {
-                // With more than one source implementation, we will probably need to probe first
-                THROW_HR_IF(E_INVALIDARG, !details.Type.empty() && details.Type != PreIndexedPackageSourceFactory::Type());
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PreIndexedPackage);
 
                 return CreateInternal(details);
             }
@@ -209,16 +208,9 @@ namespace AppInstaller::Repository::Microsoft
 
             bool Add(SourceDetails& details, IProgressCallback& progress) override final
             {
-                if (details.Type.empty())
-                {
-                    // With more than one source implementation, we will probably need to probe first
-                    details.Type = PreIndexedPackageSourceFactory::Type();
-                    AICLI_LOG(Repo, Info, << "Initializing source type: " << details.Name << " => " << details.Type);
-                }
-                else
-                {
-                    THROW_HR_IF(E_INVALIDARG, details.Type != PreIndexedPackageSourceFactory::Type());
-                }
+                // Source type is normalized before reaching the factory; this path only accepts PreIndexedPackage.
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PreIndexedPackage);
+                AICLI_LOG(Repo, Info, << "Initializing source type: " << details.Name << " => " << SourceTypeEnumToString(details.Type));
 
                 PreIndexedPackageInfo packageInfo(details, [](const std::string& packageLocation)
                     {
@@ -286,7 +278,7 @@ namespace AppInstaller::Repository::Microsoft
 
             bool Remove(const SourceDetails& details, IProgressCallback& progress) override final
             {
-                THROW_HR_IF(E_INVALIDARG, details.Type != PreIndexedPackageSourceFactory::Type());
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PreIndexedPackage);
                 auto lock = LockExclusive(details, progress);
                 if (!lock)
                 {
@@ -318,7 +310,7 @@ namespace AppInstaller::Repository::Microsoft
 
             bool UpdateBase(const SourceDetails& details, bool isBackground, IProgressCallback& progress)
             {
-                THROW_HR_IF(E_INVALIDARG, details.Type != PreIndexedPackageSourceFactory::Type());
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PreIndexedPackage);
 
                 std::optional<Msix::PackageVersion> currentVersion = GetCurrentVersion(details);
                 PreIndexedPackageUpdateCheck updateCheck(details);
diff --git a/src/AppInstallerRepositoryCore/Microsoft/PredefinedInstalledSourceFactory.cpp b/src/AppInstallerRepositoryCore/Microsoft/PredefinedInstalledSourceFactory.cpp
index 40edd79e16..321801adcc 100644
--- a/src/AppInstallerRepositoryCore/Microsoft/PredefinedInstalledSourceFactory.cpp
+++ b/src/AppInstallerRepositoryCore/Microsoft/PredefinedInstalledSourceFactory.cpp
@@ -423,7 +423,7 @@ namespace AppInstaller::Repository::Microsoft
 
             std::shared_ptr<ISourceReference> Create(const SourceDetails& details) override final
             {
-                THROW_HR_IF(E_INVALIDARG, details.Type != PredefinedInstalledSourceFactory::Type());
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PredefinedInstalled);
 
                 return std::make_shared<PredefinedInstalledSourceReference>(details);
             }
diff --git a/src/AppInstallerRepositoryCore/Microsoft/PredefinedWriteableSourceFactory.cpp b/src/AppInstallerRepositoryCore/Microsoft/PredefinedWriteableSourceFactory.cpp
index 23c645a485..a0efae604f 100644
--- a/src/AppInstallerRepositoryCore/Microsoft/PredefinedWriteableSourceFactory.cpp
+++ b/src/AppInstallerRepositoryCore/Microsoft/PredefinedWriteableSourceFactory.cpp
@@ -85,7 +85,7 @@ namespace AppInstaller::Repository::Microsoft
 
         std::shared_ptr<ISourceReference> PredefinedWriteableSourceFactoryImpl::Create(const SourceDetails& details)
         {
-            THROW_HR_IF(E_INVALIDARG, details.Type != PredefinedWriteableSourceFactory::Type());
+            THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PredefinedWriteable);
 
             return std::make_shared<PredefinedWriteableSourceReference>(details);
         }
diff --git a/src/AppInstallerRepositoryCore/PackageTrackingCatalog.cpp b/src/AppInstallerRepositoryCore/PackageTrackingCatalog.cpp
index bcbfb91292..188c0a326e 100644
--- a/src/AppInstallerRepositoryCore/PackageTrackingCatalog.cpp
+++ b/src/AppInstallerRepositoryCore/PackageTrackingCatalog.cpp
@@ -110,7 +110,7 @@ namespace AppInstaller::Repository
 
             std::shared_ptr<ISourceReference> Create(const SourceDetails& details) override final
             {
-                THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, PackageTrackingCatalogSourceFactory::Type()));
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PackageTracking);
 
                 return std::make_shared<PackageTrackingCatalogSourceReference>(details);
             }
@@ -127,7 +127,7 @@ namespace AppInstaller::Repository
 
             bool Remove(const SourceDetails& details, IProgressCallback& progress) override final
             {
-                THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, PackageTrackingCatalogSourceFactory::Type()));
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::PackageTracking);
 
                 std::string pathName = Utility::MakeSuitablePathPart(details.Data);
 
@@ -172,7 +172,7 @@ namespace AppInstaller::Repository
 
         // Create fake details for the source while stashing some information that might be helpful for debugging
         SourceDetails details;
-        details.Type = PackageTrackingCatalogSourceFactory::Type();
+        details.Type = SourceType::PackageTracking;
         details.Identifier = "*Tracking";
         details.Name = "Tracking for "s + source.GetDetails().Name;
         details.Origin = SourceOrigin::PackageTracking;
@@ -182,7 +182,7 @@ namespace AppInstaller::Repository
 
         PackageTrackingCatalog result;
         result.m_implementation = std::make_shared<PackageTrackingCatalog::implementation>();
-        result.m_implementation->Source = SourceCast<SQLiteIndexSource>(ISourceFactory::GetForType(details.Type)->Create(details)->Open(dummyProgress));
+        result.m_implementation->Source = SourceCast<SQLiteIndexSource>(ISourceFactory::GetForType(SourceType::PackageTracking)->Create(details)->Open(dummyProgress));
 
         return result;
     }
@@ -196,12 +196,12 @@ namespace AppInstaller::Repository
 
         // Create details to pass to the factory; the identifier of the source is passed in the Data field.
         SourceDetails dummyDetails;
-        dummyDetails.Type = PackageTrackingCatalogSourceFactory::Type();
+        dummyDetails.Type = SourceType::PackageTracking;
         dummyDetails.Data = identifier;
 
         ProgressCallback dummyProgress;
 
-        ISourceFactory::GetForType(dummyDetails.Type)->Remove(dummyDetails, dummyProgress);
+        ISourceFactory::GetForType(SourceType::PackageTracking)->Remove(dummyDetails, dummyProgress);
     }
 
     PackageTrackingCatalog::operator bool() const
diff --git a/src/AppInstallerRepositoryCore/Public/winget/RepositorySource.h b/src/AppInstallerRepositoryCore/Public/winget/RepositorySource.h
index f772a8f8a1..3c277de440 100644
--- a/src/AppInstallerRepositoryCore/Public/winget/RepositorySource.h
+++ b/src/AppInstallerRepositoryCore/Public/winget/RepositorySource.h
@@ -61,6 +61,26 @@ namespace AppInstaller::Repository
     // Gets the full trust level string name for display.
     std::string GetSourceTrustLevelForDisplay(SourceTrustLevel trustLevel);
 
+    // Defines known source types.
+    enum class SourceType
+    {
+        PreIndexedPackage,
+        Rest,
+        PredefinedInstalled,
+        PredefinedWriteable,
+        PackageTracking,
+        ConfigurableTest,
+    };
+
+    // Converts a source type string to the corresponding SourceType enum.
+    SourceType ConvertToSourceTypeEnum(std::string_view sourceType);
+
+    // Attempts to convert a source type string to the corresponding SourceType enum.
+    std::optional<SourceType> TryConvertToSourceTypeEnum(std::string_view sourceType);
+
+    // Converts a SourceType enum to the corresponding canonical string.
+    std::string_view SourceTypeEnumToString(SourceType sourceType);
+
     std::string_view ToString(SourceOrigin origin);
 
     // Fields that require user agreements.
@@ -120,7 +140,9 @@ namespace AppInstaller::Repository
         std::string Name;
 
         // The type of the source.
-        std::string Type;
+        // Defaults to PreIndexedPackage if not specified, moved here from call sites during migration from
+        // String type to Enum type to avoid conversion in multiple places.
+        SourceType Type = SourceType::PreIndexedPackage;
 
         // The argument used when adding the source.
         std::string Arg;
@@ -240,7 +262,7 @@ namespace AppInstaller::Repository
         Source(WellKnownSource source);
 
         // Constructor for a source to be added.
-        Source(std::string_view name, std::string_view arg, std::string_view type, SourceTrustLevel trustLevel, const SourceEdit& additionalProperties);
+        Source(std::string_view name, std::string_view arg, SourceType type, SourceTrustLevel trustLevel, const SourceEdit& additionalProperties);
 
         // Constructor for creating a composite source from a list of available sources.
         Source(const std::vector<Source>& availableSources);
@@ -373,7 +395,7 @@ namespace AppInstaller::Repository
         static std::vector<SourceDetails> GetCurrentSources();
 
         // Get a default source type is the source type used when adding a source without specifying a type.
-        static std::string_view GetDefaultSourceType();
+        static SourceType GetDefaultSourceType();
 
     private:
         void InitializeSourceReference(std::string_view name);
diff --git a/src/AppInstallerRepositoryCore/RepositorySource.cpp b/src/AppInstallerRepositoryCore/RepositorySource.cpp
index ac273fc0c8..dc7bdf26f1 100644
--- a/src/AppInstallerRepositoryCore/RepositorySource.cpp
+++ b/src/AppInstallerRepositoryCore/RepositorySource.cpp
@@ -28,7 +28,7 @@ namespace AppInstaller::Repository
     namespace
     {
 #ifndef AICLI_DISABLE_TEST_HOOKS
-        static std::map<std::string, std::function<std::unique_ptr<ISourceFactory>()>> s_Sources_TestHook_SourceFactories;
+        static std::map<SourceType, std::function<std::unique_ptr<ISourceFactory>()>> s_Sources_TestHook_SourceFactories;
 #endif
 
         std::shared_ptr<ISourceReference> CreateSourceFromDetails(const SourceDetails& details)
@@ -160,31 +160,31 @@ namespace AppInstaller::Repository
             switch (source)
             {
             case PredefinedSource::Installed:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::None);
                 return details;
             case PredefinedSource::InstalledForceCacheUpdate:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::NoneWithForcedCacheUpdate);
                 return details;
             case PredefinedSource::InstalledUser:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::User);
                 return details;
             case PredefinedSource::InstalledMachine:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::Machine);
                 return details;
             case PredefinedSource::ARP:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::ARP);
                 return details;
             case PredefinedSource::MSIX:
-                details.Type = Microsoft::PredefinedInstalledSourceFactory::Type();
+                details.Type = SourceType::PredefinedInstalled;
                 details.Arg = Microsoft::PredefinedInstalledSourceFactory::FilterToString(Microsoft::PredefinedInstalledSourceFactory::Filter::MSIX);
                 return details;
             case PredefinedSource::Installing:
-                details.Type = Microsoft::PredefinedWriteableSourceFactory::Type();
+                details.Type = SourceType::PredefinedWriteable;
                 // As long as there is only one type this is not particularly needed, but Arg is exposed publicly
                 // so this is used here for consistency with other predefined sources.
                 details.Arg = Microsoft::PredefinedWriteableSourceFactory::TypeToString(Microsoft::PredefinedWriteableSourceFactory::WriteableType::Installing);
@@ -276,46 +276,106 @@ namespace AppInstaller::Repository
         };
     }
 
-    std::unique_ptr<ISourceFactory> ISourceFactory::GetForType(std::string_view type)
+    std::unique_ptr<ISourceFactory> ISourceFactory::GetForType(SourceType type)
     {
 #ifndef AICLI_DISABLE_TEST_HOOKS
         // Tests can ensure case matching
-        auto itr = s_Sources_TestHook_SourceFactories.find(std::string(type));
+        auto itr = s_Sources_TestHook_SourceFactories.find(type);
         if (itr != s_Sources_TestHook_SourceFactories.end())
         {
             return itr->second();
         }
+#endif
 
-        if (Utility::CaseInsensitiveEquals(Microsoft::ConfigurableTestSourceFactory::Type(), type))
+        switch (type)
         {
+        case SourceType::PreIndexedPackage:
+            return Microsoft::PreIndexedPackageSourceFactory::Create();
+        case SourceType::Rest:
+            return Rest::RestSourceFactory::Create();
+        case SourceType::PredefinedInstalled:
+            return Microsoft::PredefinedInstalledSourceFactory::Create();
+        case SourceType::PredefinedWriteable:
+            return Microsoft::PredefinedWriteableSourceFactory::Create();
+        case SourceType::PackageTracking:
+            return PackageTrackingCatalogSourceFactory::Create();
+#ifndef AICLI_DISABLE_TEST_HOOKS
+        case SourceType::ConfigurableTest:
             return Microsoft::ConfigurableTestSourceFactory::Create();
-        }
+#else
+        case SourceType::ConfigurableTest:
+            break;
 #endif
+        }
 
-        // For now, enable an empty type to represent the only one we have.
-        if (type.empty() ||
-            Utility::CaseInsensitiveEquals(Microsoft::PreIndexedPackageSourceFactory::Type(), type))
+        THROW_HR(APPINSTALLER_CLI_ERROR_INVALID_SOURCE_TYPE);
+    }
+
+    std::optional<SourceType> TryConvertToSourceTypeEnum(std::string_view sourceType)
+    {
+        if (Utility::CaseInsensitiveEquals(Microsoft::PreIndexedPackageSourceFactory::Type(), sourceType))
         {
-            return Microsoft::PreIndexedPackageSourceFactory::Create();
+            return SourceType::PreIndexedPackage;
         }
-        // Should always come from code, so no need for case insensitivity
-        else if (Microsoft::PredefinedInstalledSourceFactory::Type() == type)
+
+        if (Utility::CaseInsensitiveEquals(Rest::RestSourceFactory::Type(), sourceType))
         {
-            return Microsoft::PredefinedInstalledSourceFactory::Create();
+            return SourceType::Rest;
         }
-        // Should always come from code, so no need for case insensitivity
-        else if (Microsoft::PredefinedWriteableSourceFactory::Type() == type)
+
+        // Internal source types are code-defined and expected in canonical case.
+        if (Microsoft::PredefinedInstalledSourceFactory::Type() == sourceType)
         {
-            return Microsoft::PredefinedWriteableSourceFactory::Create();
+            return SourceType::PredefinedInstalled;
         }
-        // Should always come from code, so no need for case insensitivity
-        else if (PackageTrackingCatalogSourceFactory::Type() == type)
+
+        if (Microsoft::PredefinedWriteableSourceFactory::Type() == sourceType)
         {
-            return PackageTrackingCatalogSourceFactory::Create();
+            return SourceType::PredefinedWriteable;
         }
-        else if (Utility::CaseInsensitiveEquals(Rest::RestSourceFactory::Type(), type))
+
+        if (PackageTrackingCatalogSourceFactory::Type() == sourceType)
         {
-            return Rest::RestSourceFactory::Create();
+            return SourceType::PackageTracking;
+        }
+
+#ifndef AICLI_DISABLE_TEST_HOOKS
+        if (Utility::CaseInsensitiveEquals(Microsoft::ConfigurableTestSourceFactory::Type(), sourceType))
+        {
+            return SourceType::ConfigurableTest;
+        }
+#endif
+
+        return {};
+    }
+
+    SourceType ConvertToSourceTypeEnum(std::string_view sourceType)
+    {
+        auto sourceTypeEnum = TryConvertToSourceTypeEnum(sourceType);
+        THROW_HR_IF(APPINSTALLER_CLI_ERROR_INVALID_SOURCE_TYPE, !sourceTypeEnum.has_value());
+        return sourceTypeEnum.value();
+    }
+
+    std::string_view SourceTypeEnumToString(SourceType sourceType)
+    {
+        switch (sourceType)
+        {
+        case SourceType::PreIndexedPackage:
+            return Microsoft::PreIndexedPackageSourceFactory::Type();
+        case SourceType::Rest:
+            return Rest::RestSourceFactory::Type();
+        case SourceType::PredefinedInstalled:
+            return Microsoft::PredefinedInstalledSourceFactory::Type();
+        case SourceType::PredefinedWriteable:
+            return Microsoft::PredefinedWriteableSourceFactory::Type();
+        case SourceType::PackageTracking:
+            return PackageTrackingCatalogSourceFactory::Type();
+        case SourceType::ConfigurableTest:
+#ifndef AICLI_DISABLE_TEST_HOOKS
+            return Microsoft::ConfigurableTestSourceFactory::Type();
+#else
+            break;
+#endif
         }
 
         THROW_HR(APPINSTALLER_CLI_ERROR_INVALID_SOURCE_TYPE);
@@ -462,11 +522,10 @@ namespace AppInstaller::Repository
         m_sourceReferences.emplace_back(CreateSourceFromDetails(details));
     }
 
-    Source::Source(std::string_view name, std::string_view arg, std::string_view type, SourceTrustLevel trustLevel, const SourceEdit& additionalProperties)
+    Source::Source(std::string_view name, std::string_view arg, SourceType type, SourceTrustLevel trustLevel, const SourceEdit& additionalProperties)
     {
         m_isSourceToBeAdded = true;
         SourceDetails details;
-
         std::optional<WellKnownSource> wellKnownSourceCheck = CheckForWellKnownSourceMatch(name, arg, type);
 
         if (wellKnownSourceCheck)
@@ -907,14 +966,8 @@ namespace AppInstaller::Repository
 
         auto& sourceDetails = m_sourceReferences[0]->GetDetails();
 
-        // If the source type is empty, use a default.
-        // AddSourceForDetails will also check for empty, but we need the actual type before that for validation.
-        if (sourceDetails.Type.empty())
-        {
-            sourceDetails.Type = GetDefaultSourceType();
-        }
-
-        AICLI_LOG(Repo, Info, << "Adding source: Name[" << sourceDetails.Name << "], Type[" << sourceDetails.Type << "], Arg[" << sourceDetails.Arg << "]");
+        // If the source type was empty, the constructor of sourceDetails will have defaulted it
+        AICLI_LOG(Repo, Info, << "Adding source: Name[" << sourceDetails.Name << "], Type[" << SourceTypeEnumToString(sourceDetails.Type) << "], Arg[" << sourceDetails.Arg << "]");
 
         // Check all sources for the given name.
         SourceList sourceList;
@@ -1131,13 +1184,13 @@ namespace AppInstaller::Repository
         }
     }
 
-    std::string_view Source::GetDefaultSourceType()
+    SourceType Source::GetDefaultSourceType()
     {
-        return ISourceFactory::GetForType("")->TypeName();
+        return SourceType::PreIndexedPackage;
     }
 
 #ifndef AICLI_DISABLE_TEST_HOOKS
-    void TestHook_SetSourceFactoryOverride(const std::string& type, std::function<std::unique_ptr<ISourceFactory>()>&& factory)
+    void TestHook_SetSourceFactoryOverride(SourceType type, std::function<std::unique_ptr<ISourceFactory>()>&& factory)
     {
         s_Sources_TestHook_SourceFactories[type] = std::move(factory);
     }
diff --git a/src/AppInstallerRepositoryCore/Rest/RestSourceFactory.cpp b/src/AppInstallerRepositoryCore/Rest/RestSourceFactory.cpp
index 8074f348b8..dc9e2001fb 100644
--- a/src/AppInstallerRepositoryCore/Rest/RestSourceFactory.cpp
+++ b/src/AppInstallerRepositoryCore/Rest/RestSourceFactory.cpp
@@ -117,21 +117,15 @@ namespace AppInstaller::Repository::Rest
 
             std::shared_ptr<ISourceReference> Create(const SourceDetails& details) override final
             {
-                THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, RestSourceFactory::Type()));
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::Rest);
 
                 return std::make_shared<RestSourceReference>(details);
             }
 
             bool Add(SourceDetails& details, IProgressCallback&) override final
             {
-                if (details.Type.empty())
-                {
-                    details.Type = RestSourceFactory::Type();
-                }
-                else
-                {
-                    THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, RestSourceFactory::Type()));
-                }
+                // Source type is normalized before reaching the factory; this path only accepts Rest.
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::Rest);
 
                 // Check if URL is remote and secure
                 THROW_HR_IF(APPINSTALLER_CLI_ERROR_SOURCE_NOT_REMOTE, !Utility::IsUrlRemote(details.Arg));
@@ -142,13 +136,13 @@ namespace AppInstaller::Repository::Rest
 
             bool Update(const SourceDetails& details, IProgressCallback&) override final
             {
-                THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, RestSourceFactory::Type()));
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::Rest);
                 return true;
             }
 
             bool Remove(const SourceDetails& details, IProgressCallback&) override final
             {
-                THROW_HR_IF(E_INVALIDARG, !Utility::CaseInsensitiveEquals(details.Type, RestSourceFactory::Type()));
+                THROW_HR_IF(E_INVALIDARG, details.Type != SourceType::Rest);
                 return true;
             }
         };
diff --git a/src/AppInstallerRepositoryCore/SourceFactory.h b/src/AppInstallerRepositoryCore/SourceFactory.h
index 85a6ffd25a..aafb371f0c 100644
--- a/src/AppInstallerRepositoryCore/SourceFactory.h
+++ b/src/AppInstallerRepositoryCore/SourceFactory.h
@@ -42,6 +42,6 @@ namespace AppInstaller::Repository
         virtual bool Remove(const SourceDetails& details, IProgressCallback& progress) = 0;
 
         // Gets the factory for the given type.
-        static std::unique_ptr<ISourceFactory> GetForType(std::string_view type);
+        static std::unique_ptr<ISourceFactory> GetForType(SourceType type);
     };
 }
diff --git a/src/AppInstallerRepositoryCore/SourceList.cpp b/src/AppInstallerRepositoryCore/SourceList.cpp
index 6462aeb98e..5b290a39b7 100644
--- a/src/AppInstallerRepositoryCore/SourceList.cpp
+++ b/src/AppInstallerRepositoryCore/SourceList.cpp
@@ -3,8 +3,6 @@
 #include "pch.h"
 #include "SourceList.h"
 #include "SourcePolicy.h"
-#include "Microsoft/PreIndexedPackageSourceFactory.h"
-#include "Rest/RestSourceFactory.h"
 
 #include <winget/AdminSettings.h>
 #include <winget/Certificates.h>
@@ -185,7 +183,7 @@ namespace AppInstaller::Repository
                 {
                     out << YAML::BeginMap;
                     out << YAML::Key << s_SourcesYaml_Source_Name << YAML::Value << details.Name;
-                    out << YAML::Key << s_SourcesYaml_Source_Type << YAML::Value << details.Type;
+                    out << YAML::Key << s_SourcesYaml_Source_Type << YAML::Value << SourceTypeEnumToString(details.Type);
                     out << YAML::Key << s_SourcesYaml_Source_Arg << YAML::Value << details.Arg;
                     out << YAML::Key << s_SourcesYaml_Source_Data << YAML::Value << details.Data;
                     out << YAML::Key << s_SourcesYaml_Source_Identifier << YAML::Value << details.Identifier;
@@ -209,7 +207,7 @@ namespace AppInstaller::Repository
         {
             return left.Arg == right.Arg &&
                 left.Identifier == right.Identifier &&
-                Utility::CaseInsensitiveEquals(left.Type, right.Type);
+                left.Type == right.Type;
         }
 
         bool ShouldBeHidden(const SourceDetailsInternal& details)
@@ -312,24 +310,24 @@ namespace AppInstaller::Repository
         return {};
     }
 
-    std::optional<WellKnownSource> CheckForWellKnownSourceMatch(std::string_view name, std::string_view arg, std::string_view type)
+    std::optional<WellKnownSource> CheckForWellKnownSourceMatch(std::string_view name, std::string_view arg, SourceType type)
     {
-        if (name == s_Source_WingetCommunityDefault_Name && arg == s_Source_WingetCommunityDefault_Arg && type == Microsoft::PreIndexedPackageSourceFactory::Type())
+        if (name == s_Source_WingetCommunityDefault_Name && arg == s_Source_WingetCommunityDefault_Arg && type == SourceType::PreIndexedPackage)
         {
             return WellKnownSource::WinGet;
         }
 
-        if (name == s_Source_MSStoreDefault_Name && arg == s_Source_MSStoreDefault_Arg && type == Rest::RestSourceFactory::Type())
+        if (name == s_Source_MSStoreDefault_Name && arg == s_Source_MSStoreDefault_Arg && type == SourceType::Rest)
         {
             return WellKnownSource::MicrosoftStore;
         }
 
-        if (name == s_Source_DesktopFrameworks_Name && arg == s_Source_DesktopFrameworks_Arg && type == Microsoft::PreIndexedPackageSourceFactory::Type())
+        if (name == s_Source_DesktopFrameworks_Name && arg == s_Source_DesktopFrameworks_Arg && type == SourceType::PreIndexedPackage)
         {
             return WellKnownSource::DesktopFrameworks;
         }
 
-        if (name == s_Source_WingetCommunityFont_Name && arg == s_Source_WingetCommunityFont_Arg && type == Rest::RestSourceFactory::Type())
+        if (name == s_Source_WingetCommunityFont_Name && arg == s_Source_WingetCommunityFont_Arg && type == SourceType::PreIndexedPackage)
         {
             return WellKnownSource::WinGetFont;
         }
@@ -346,7 +344,7 @@ namespace AppInstaller::Repository
             SourceDetailsInternal details;
             details.Origin = SourceOrigin::Default;
             details.Name = s_Source_WingetCommunityDefault_Name;
-            details.Type = Microsoft::PreIndexedPackageSourceFactory::Type();
+            details.Type = SourceType::PreIndexedPackage;
             details.Arg = s_Source_WingetCommunityDefault_Arg;
             details.Data = s_Source_WingetCommunityDefault_Data;
             details.Identifier = s_Source_WingetCommunityDefault_Identifier;
@@ -358,7 +356,7 @@ namespace AppInstaller::Repository
             SourceDetailsInternal details;
             details.Origin = SourceOrigin::Default;
             details.Name = s_Source_MSStoreDefault_Name;
-            details.Type = Rest::RestSourceFactory::Type();
+            details.Type = SourceType::Rest;
             details.Arg = s_Source_MSStoreDefault_Arg;
             details.Identifier = s_Source_MSStoreDefault_Identifier;
             details.TrustLevel = SourceTrustLevel::Trusted;
@@ -391,7 +389,7 @@ namespace AppInstaller::Repository
             SourceDetailsInternal details;
             details.Origin = SourceOrigin::Default;
             details.Name = s_Source_DesktopFrameworks_Name;
-            details.Type = Microsoft::PreIndexedPackageSourceFactory::Type();
+            details.Type = SourceType::PreIndexedPackage;
             details.Arg = s_Source_DesktopFrameworks_Arg;
             details.Data = s_Source_DesktopFrameworks_Data;
             details.Identifier = s_Source_DesktopFrameworks_Identifier;
@@ -404,7 +402,7 @@ namespace AppInstaller::Repository
             SourceDetailsInternal details;
             details.Origin = SourceOrigin::Default;
             details.Name = s_Source_WingetCommunityFont_Name;
-            details.Type = Microsoft::PreIndexedPackageSourceFactory::Type();
+            details.Type = SourceType::PreIndexedPackage;
             details.Arg = s_Source_WingetCommunityFont_Arg;
             details.Data = s_Source_WingetCommunityFont_Data;
             details.Identifier = s_Source_WingetCommunityFont_Identifier;
@@ -820,7 +818,6 @@ namespace AppInstaller::Repository
                 {
                     std::string_view name = m_userSourcesStream.GetName();
                     if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Name, details.Name)) { return false; }
-                    if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Type, details.Type)) { return false; }
                     if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Arg, details.Arg)) { return false; }
                     if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Data, details.Data)) { return false; }
                     if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_IsTombstone, details.IsTombstone)) { return false; }
@@ -829,6 +826,20 @@ namespace AppInstaller::Repository
                     TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_IsOverride, details.IsOverride, false);
                     TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Priority, details.Priority, false);
 
+                    std::string type;
+                    if (!TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_Type, type)) { return false; }
+                    if (type.empty() && (details.IsTombstone || details.IsOverride))
+                    {
+                        // Legacy tombstone/override entries may carry empty type strings.
+                        details.Type = Source::GetDefaultSourceType();
+                    }
+                    else
+                    {
+                        auto sourceType = TryConvertToSourceTypeEnum(type);
+                        if (!sourceType) { return false; }
+                        details.Type = sourceType.value();
+                    }
+
                     int64_t trustLevelValue;
                     if (TryReadScalar(name, settingValue, source, s_SourcesYaml_Source_TrustLevel, trustLevelValue, false))
                     {
@@ -884,7 +895,13 @@ namespace AppInstaller::Repository
                         AICLI_LOG(Repo, Verbose, << "... with configured source " << additionalSource.Name);
                         SourceDetailsInternal details;
                         details.Name = additionalSource.Name;
-                        details.Type = additionalSource.Type;
+                        auto sourceType = TryConvertToSourceTypeEnum(additionalSource.Type);
+                        if (!sourceType)
+                        {
+                            AICLI_LOG(Repo, Warning, << "Invalid source type from policy source: " << additionalSource.Type);
+                            continue;
+                        }
+                        details.Type = sourceType.value();
                         details.Arg = additionalSource.Arg;
                         details.Data = additionalSource.Data;
                         details.Identifier = additionalSource.Identifier;
diff --git a/src/AppInstallerRepositoryCore/SourceList.h b/src/AppInstallerRepositoryCore/SourceList.h
index 2230715209..b1f7c5e269 100644
--- a/src/AppInstallerRepositoryCore/SourceList.h
+++ b/src/AppInstallerRepositoryCore/SourceList.h
@@ -11,7 +11,7 @@ namespace AppInstaller::Repository
     std::string_view GetWellKnownSourceName(WellKnownSource source);
     std::string_view GetWellKnownSourceArg(WellKnownSource source);
     std::string_view GetWellKnownSourceIdentifier(WellKnownSource source);
-    std::optional<WellKnownSource> CheckForWellKnownSourceMatch(std::string_view name, std::string_view arg, std::string_view type);
+    std::optional<WellKnownSource> CheckForWellKnownSourceMatch(std::string_view name, std::string_view arg, SourceType type);
 
     // SourceDetails with additional data used internally.
     struct SourceDetailsInternal : public SourceDetails
diff --git a/src/AppInstallerRepositoryCore/SourcePolicy.cpp b/src/AppInstallerRepositoryCore/SourcePolicy.cpp
index 22fabc7a80..9f9f5521ff 100644
--- a/src/AppInstallerRepositoryCore/SourcePolicy.cpp
+++ b/src/AppInstallerRepositoryCore/SourcePolicy.cpp
@@ -2,8 +2,6 @@
 // Licensed under the MIT License.
 #include "pch.h"
 #include "SourcePolicy.h"
-#include "Microsoft/PreIndexedPackageSourceFactory.h"
-#include "Rest/RestSourceFactory.h"
 
 using namespace AppInstaller::Settings;
 
@@ -38,7 +36,7 @@ namespace AppInstaller::Repository
         }
 
         template<ValuePolicy P>
-        std::optional<SourceFromPolicy> FindSourceInPolicy(std::string_view name, std::string_view type, std::string_view arg)
+        std::optional<SourceFromPolicy> FindSourceInPolicy(std::string_view name, SourceType type, std::string_view arg)
         {
             auto sourcesOpt = GroupPolicies().GetValue<P>();
             if (!sourcesOpt.has_value())
@@ -52,7 +50,9 @@ namespace AppInstaller::Repository
                 sources.end(),
                 [&](const SourceFromPolicy& policySource)
                 {
-                    return Utility::ICUCaseInsensitiveEquals(name, policySource.Name) && Utility::ICUCaseInsensitiveEquals(type, policySource.Type) && arg == policySource.Arg;
+                    return Utility::ICUCaseInsensitiveEquals(name, policySource.Name) &&
+                        Utility::ICUCaseInsensitiveEquals(SourceTypeEnumToString(type), policySource.Type) &&
+                        arg == policySource.Arg;
                 });
 
             if (source == sources.end())
@@ -64,7 +64,7 @@ namespace AppInstaller::Repository
         }
 
         template<ValuePolicy P>
-        bool IsSourceInPolicy(std::string_view name, std::string_view type, std::string_view arg)
+        bool IsSourceInPolicy(std::string_view name, SourceType type, std::string_view arg)
         {
             return FindSourceInPolicy<P>(name, type, arg).has_value();
         }
@@ -74,7 +74,7 @@ namespace AppInstaller::Repository
     // If it does it returns None, otherwise it returns which policy is blocking it.
     // Note that this applies to user sources that are being added as well as user sources
     // that already existed when the Group Policy came into effect.
-    TogglePolicy::Policy GetPolicyBlockingUserSource(std::string_view name, std::string_view type, std::string_view arg, bool isTombstone)
+    TogglePolicy::Policy GetPolicyBlockingUserSource(std::string_view name, SourceType type, std::string_view arg, bool isTombstone)
     {
         // Reasons for not allowing:
         //  1. The source is a tombstone for default source that is explicitly enabled
@@ -116,19 +116,19 @@ namespace AppInstaller::Repository
         //  - Do a case-insensitive check as the domain portion of the URL is case-insensitive,
         //    and we don't need case sensitivity for the rest as we control the domain.
         if (Utility::CaseInsensitiveEquals(arg, GetWellKnownSourceArg(WellKnownSource::WinGet)) &&
-            Utility::CaseInsensitiveEquals(type, Microsoft::PreIndexedPackageSourceFactory::Type()))
+            type == SourceType::PreIndexedPackage)
         {
             return IsWellKnownSourceEnabled(WellKnownSource::WinGet) ? TogglePolicy::Policy::None : TogglePolicy::Policy::DefaultSource;
         }
 
         if (Utility::CaseInsensitiveEquals(arg, GetWellKnownSourceArg(WellKnownSource::MicrosoftStore)) &&
-            Utility::CaseInsensitiveEquals(type, Rest::RestSourceFactory::Type()))
+            type == SourceType::Rest)
         {
             return IsWellKnownSourceEnabled(WellKnownSource::MicrosoftStore) ? TogglePolicy::Policy::None : TogglePolicy::Policy::MSStoreSource;
         }
 
         if (Utility::CaseInsensitiveEquals(arg, GetWellKnownSourceArg(WellKnownSource::WinGetFont)) &&
-            Utility::CaseInsensitiveEquals(type, Microsoft::PreIndexedPackageSourceFactory::Type()))
+            type == SourceType::PreIndexedPackage)
         {
             return IsWellKnownSourceEnabled(WellKnownSource::WinGetFont) ? TogglePolicy::Policy::None : TogglePolicy::Policy::FontSource;
         }
@@ -138,19 +138,19 @@ namespace AppInstaller::Repository
         // (as it didn't match above). We only care if Group Policy requires the default source.
         if (name == GetWellKnownSourceName(WellKnownSource::WinGet) && IsWellKnownSourceEnabled(WellKnownSource::WinGet, true))
         {
-            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows the default source. Name [" << name << "]. Arg [" << arg << "] Type [" << type << ']');
+            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows the default source. Name [" << name << "]. Arg [" << arg << "] Type [" << SourceTypeEnumToString(type) << ']');
             return TogglePolicy::Policy::DefaultSource;
         }
 
         if (name == GetWellKnownSourceName(WellKnownSource::MicrosoftStore) && IsWellKnownSourceEnabled(WellKnownSource::MicrosoftStore, true))
         {
-            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows a default MS Store source. Name [" << name << "]. Arg [" << arg << "] Type [" << type << ']');
+            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows a default MS Store source. Name [" << name << "]. Arg [" << arg << "] Type [" << SourceTypeEnumToString(type) << ']');
             return TogglePolicy::Policy::MSStoreSource;
         }
 
         if (name == GetWellKnownSourceName(WellKnownSource::WinGetFont) && IsWellKnownSourceEnabled(WellKnownSource::WinGetFont, true))
         {
-            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows a default font source. Name [" << name << "]. Arg [" << arg << "] Type [" << type << ']');
+            AICLI_LOG(Repo, Warning, << "User source is not allowed as it shadows a default font source. Name [" << name << "]. Arg [" << arg << "] Type [" << SourceTypeEnumToString(type) << ']');
             return TogglePolicy::Policy::FontSource;
         }
 
@@ -169,7 +169,7 @@ namespace AppInstaller::Repository
         {
             if (!IsSourceInPolicy<ValuePolicy::AllowedSources>(name, type, arg))
             {
-                AICLI_LOG(Repo, Warning, << "Source is not in the Group Policy allowed list. Name [" << name << "]. Arg [" << arg << "] Type [" << type << ']');
+                AICLI_LOG(Repo, Warning, << "Source is not in the Group Policy allowed list. Name [" << name << "]. Arg [" << arg << "] Type [" << SourceTypeEnumToString(type) << ']');
                 return TogglePolicy::Policy::AllowedSources;
             }
         }
@@ -177,7 +177,7 @@ namespace AppInstaller::Repository
         return TogglePolicy::Policy::None;
     }
 
-    bool IsUserSourceAllowedByPolicy(std::string_view name, std::string_view type, std::string_view arg, bool isTombstone)
+    bool IsUserSourceAllowedByPolicy(std::string_view name, SourceType type, std::string_view arg, bool isTombstone)
     {
         return GetPolicyBlockingUserSource(name, type, arg, isTombstone) == TogglePolicy::Policy::None;
     }
diff --git a/src/AppInstallerRepositoryCore/SourcePolicy.h b/src/AppInstallerRepositoryCore/SourcePolicy.h
index 3f3afb3c13..694fb9700a 100644
--- a/src/AppInstallerRepositoryCore/SourcePolicy.h
+++ b/src/AppInstallerRepositoryCore/SourcePolicy.h
@@ -13,10 +13,10 @@ namespace AppInstaller::Repository
     // If it does it returns None, otherwise it returns which policy is blocking it.
     // Note that this applies to user sources that are being added as well as user sources
     // that already existed when the Group Policy came into effect.
-    Settings::TogglePolicy::Policy GetPolicyBlockingUserSource(std::string_view name, std::string_view type, std::string_view arg, bool isTombstone);
+    Settings::TogglePolicy::Policy GetPolicyBlockingUserSource(std::string_view name, SourceType type, std::string_view arg, bool isTombstone);
 
     // Helper that converts the result of GetPolicyBlockingUserSource into a bool.
-    bool IsUserSourceAllowedByPolicy(std::string_view name, std::string_view type, std::string_view arg, bool isTombstone);
+    bool IsUserSourceAllowedByPolicy(std::string_view name, SourceType type, std::string_view arg, bool isTombstone);
 
     // Determines if a well known source is enabled; if onlyExplicit is true, it must be explicitly enabled by group policy.
     bool IsWellKnownSourceEnabled(WellKnownSource source, bool onlyExplicit = false);
diff --git a/src/Microsoft.Management.Deployment/PackageCatalogInfo.cpp b/src/Microsoft.Management.Deployment/PackageCatalogInfo.cpp
index 0306cb58b9..ed4b83a1d6 100644
--- a/src/Microsoft.Management.Deployment/PackageCatalogInfo.cpp
+++ b/src/Microsoft.Management.Deployment/PackageCatalogInfo.cpp
@@ -25,7 +25,7 @@ namespace winrt::Microsoft::Management::Deployment::implementation
     }
     hstring PackageCatalogInfo::Type()
     {
-        return winrt::to_hstring(m_sourceDetails.Type);
+        return winrt::to_hstring(::AppInstaller::Repository::SourceTypeEnumToString(m_sourceDetails.Type));
     }
     hstring PackageCatalogInfo::Argument()
     {
diff --git a/src/Microsoft.Management.Deployment/PackageCatalogProgress.cpp b/src/Microsoft.Management.Deployment/PackageCatalogProgress.cpp
index 5a5169ad34..6563cde987 100644
--- a/src/Microsoft.Management.Deployment/PackageCatalogProgress.cpp
+++ b/src/Microsoft.Management.Deployment/PackageCatalogProgress.cpp
@@ -3,10 +3,9 @@
 #include "pch.h"
 #include "PackageCatalogProgress.h"
 #include "AppInstallerStrings.h"
-#include "Microsoft/PredefinedInstalledSourceFactory.h"
+#include <winget/RepositorySource.h>
 
 using namespace AppInstaller;
-using namespace AppInstaller::Repository;
 
 namespace winrt::Microsoft::Management::Deployment
 {
@@ -14,8 +13,8 @@ namespace winrt::Microsoft::Management::Deployment
     {
         std::shared_ptr<AppInstaller::IProgressSink> CreatePackageCatalogProgressSink(std::string sourceType, std::function<void(double)> progressReporter, bool removeOperation)
         {
-            if (sourceType.empty()
-                || Utility::CaseInsensitiveEquals( Repository::Microsoft::PredefinedInstalledSourceFactory::Type(), sourceType))
+            auto sourceTypeEnum = ::AppInstaller::Repository::TryConvertToSourceTypeEnum(sourceType).value_or(::AppInstaller::Repository::Source::GetDefaultSourceType());
+            if (sourceTypeEnum == ::AppInstaller::Repository::SourceType::PreIndexedPackage || sourceTypeEnum == ::AppInstaller::Repository::SourceType::PredefinedInstalled)
             {
                 std::vector<std::pair<AppInstaller::ProgressType, double>> progressWeights;
 
diff --git a/src/Microsoft.Management.Deployment/PackageCatalogReference.cpp b/src/Microsoft.Management.Deployment/PackageCatalogReference.cpp
index 44fa2ad604..55fd500c7b 100644
--- a/src/Microsoft.Management.Deployment/PackageCatalogReference.cpp
+++ b/src/Microsoft.Management.Deployment/PackageCatalogReference.cpp
@@ -361,7 +361,9 @@ namespace winrt::Microsoft::Management::Deployment::implementation
             auto report_progress{ co_await winrt::get_progress_token() };
             co_await winrt::resume_background();
 
-            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(this->m_sourceReference.GetDetails().Type, report_progress);
+            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(
+                std::string{ ::AppInstaller::Repository::SourceTypeEnumToString(this->m_sourceReference.GetDetails().Type) },
+                report_progress);
 
             packageCatalogProgressSink->BeginProgress();
             ::AppInstaller::ProgressCallback progress(packageCatalogProgressSink.get());
diff --git a/src/Microsoft.Management.Deployment/PackageManager.cpp b/src/Microsoft.Management.Deployment/PackageManager.cpp
index 6470aad0ed..4d97638023 100644
--- a/src/Microsoft.Management.Deployment/PackageManager.cpp
+++ b/src/Microsoft.Management.Deployment/PackageManager.cpp
@@ -68,28 +68,17 @@ namespace winrt::Microsoft::Management::Deployment::implementation
             return *addPackageCatalogResult;
         }
 
-        void CheckForDuplicateSource(const std::string& name, const std::string& type, const std::string& sourceUri)
+        void CheckForDuplicateSource(const std::string& name, ::AppInstaller::Repository::SourceType type, const std::string& sourceUri)
         {
             auto sourceList = ::AppInstaller::Repository::Source::GetCurrentSources();
 
-            std::string sourceType = type;
-
-            // [NOTE:] If the source type is not specified, the default source type will be used for validation.In cases where the source type is empty,
-            // it remains unassigned until the add operation, at which point it is assigned.Without this default assignment, an empty string could be
-            // compared to the default type, potentially allowing different source names with the same URI to be seen as unique.
-            // To avoid this, assign the default source type prior to comparison.
-            if (sourceType.empty())
-            {
-                // This method of obtaining the default source type is slightly expensive as it requires creating a SourceFactory object
-                // and fetching the type name.Nonetheless, it future-proofs the code against any changes in the SourceFactory's default type.
-                sourceType = ::AppInstaller::Repository::Source::GetDefaultSourceType();
-            }
-
+            // source type has already been normalized to enum (with default applied) at input boundary.
             for (const auto& source : sourceList)
             {
                 THROW_HR_IF(APPINSTALLER_CLI_ERROR_SOURCE_NAME_ALREADY_EXISTS, ::AppInstaller::Utility::ICUCaseInsensitiveEquals(source.Name, name));
 
-                bool sourceUriAlreadyExists = !source.Arg.empty() && source.Arg == sourceUri && source.Type == sourceType;
+                bool sourceUriAlreadyExists = !source.Arg.empty() && source.Arg == sourceUri &&
+                    source.Type == type;
                 THROW_HR_IF(APPINSTALLER_CLI_ERROR_SOURCE_ARG_ALREADY_EXISTS, sourceUriAlreadyExists);
             }
         }
@@ -97,7 +86,7 @@ namespace winrt::Microsoft::Management::Deployment::implementation
         ::AppInstaller::Repository::Source CreateSourceFromOptions(const winrt::Microsoft::Management::Deployment::AddPackageCatalogOptions& options)
         {
             std::string name = winrt::to_string(options.Name());
-            std::string type = winrt::to_string(options.Type());
+            auto sourceType = ::AppInstaller::Repository::TryConvertToSourceTypeEnum(winrt::to_string(options.Type())).value_or(::AppInstaller::Repository::Source::GetDefaultSourceType());
             std::string sourceUri = winrt::to_string(options.SourceUri());
 
             AppInstaller::Repository::SourceTrustLevel trustLevel = AppInstaller::Repository::SourceTrustLevel::None;
@@ -106,13 +95,13 @@ namespace winrt::Microsoft::Management::Deployment::implementation
                 trustLevel = AppInstaller::Repository::SourceTrustLevel::Trusted;
             }
 
-            CheckForDuplicateSource(name, type, sourceUri);
+            CheckForDuplicateSource(name, sourceType, sourceUri);
 
             ::AppInstaller::Repository::SourceEdit additionalProperties;
             additionalProperties.Explicit = options.Explicit();
             additionalProperties.Priority = options.Priority();
 
-            ::AppInstaller::Repository::Source source = ::AppInstaller::Repository::Source{ name, sourceUri, type, trustLevel, additionalProperties };
+            ::AppInstaller::Repository::Source source = ::AppInstaller::Repository::Source{ name, sourceUri, sourceType, trustLevel, additionalProperties };
 
             std::string customHeader = winrt::to_string(options.CustomHeader());
             if (!customHeader.empty())
@@ -1374,8 +1363,10 @@ namespace winrt::Microsoft::Management::Deployment::implementation
             auto report_progress{ co_await winrt::get_progress_token() };
             co_await winrt::resume_background();
 
-            std::string type = winrt::to_string(options.Type());
-            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(type, report_progress );
+            auto sourceType = ::AppInstaller::Repository::TryConvertToSourceTypeEnum(winrt::to_string(options.Type())).value_or(::AppInstaller::Repository::Source::GetDefaultSourceType());
+            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(
+                std::string{ ::AppInstaller::Repository::SourceTypeEnumToString(sourceType) },
+                report_progress);
 
             packageCatalogProgressSink->BeginProgress();
             ::AppInstaller::ProgressCallback progress(packageCatalogProgressSink.get());
@@ -1413,7 +1404,13 @@ namespace winrt::Microsoft::Management::Deployment::implementation
             auto report_progress{ co_await winrt::get_progress_token() };
             co_await winrt::resume_background();
 
-            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(matchingSource.value().Type, report_progress, true);
+            std::string normalizedSourceType = std::string{
+                ::AppInstaller::Repository::SourceTypeEnumToString(matchingSource.value().Type) };
+
+            auto packageCatalogProgressSink = winrt::Microsoft::Management::Deployment::ProgressSinkFactory::CreatePackageCatalogProgressSink(
+                normalizedSourceType,
+                report_progress,
+                true);
 
             packageCatalogProgressSink->BeginProgress();
             ::AppInstaller::Repository::Source sourceToRemove = ::AppInstaller::Repository::Source{ matchingSource.value().Name };