diff --git a/Launcher.Next.Application/LegacyConfigurationAdapters.cs b/Launcher.Next.Application/LegacyConfigurationAdapters.cs
new file mode 100644
index 0000000..4119c8d
--- /dev/null
+++ b/Launcher.Next.Application/LegacyConfigurationAdapters.cs
@@ -0,0 +1,61 @@
+using System.Xml;
+using System.Xml.Linq;
+using Launcher.Next.Core;
+
+namespace Launcher.Next.Application;
+
+public sealed record LegacyPluginDefinition(string Id, string Renewal, string Catalog, string Install, int DefinitionOrder);
+public sealed record LegacyProductPattern(string Name, string Filter, string Roster, IReadOnlyList<LegacyPluginDefinition> Plugins);
+public sealed record LegacyLauncherSettings(string Help, string CareMarker, IReadOnlyList<LegacyProductPattern> Patterns);
+public sealed record LegacyDownloadSelection(IReadOnlyList<string> PluginIds);
+public sealed record LegacyCompatibilityMapping(string LegacyId, string PackageId, string Version, string Channel);
+public sealed record LegacyCompatibilityOverlay(string MappingId, string Product, int ProductYear, string Architecture, bool AllowOfflineFallback, IReadOnlyList<LegacyCompatibilityMapping> Plugins);
+
+public sealed class LegacyConfigurationAdapter
+{
+    private static readonly XmlReaderSettings XmlSettings = new() { DtdProcessing = DtdProcessing.Prohibit, XmlResolver = null, MaxCharactersInDocument = 1_000_000 };
+
+    public LegacyLauncherSettings ParseSettings(string xml)
+    {
+        using var reader = XmlReader.Create(new StringReader(xml), XmlSettings); var root = XDocument.Load(reader).Root ?? throw new InvalidOperationException("LEGACY_SETTINGS_INVALID");
+        var path = root.Element("path") ?? throw new InvalidOperationException("LEGACY_SETTINGS_PATH_MISSING");
+        var patterns = root.Elements("data").Select(data =>
+        {
+            var pattern = data.Element("pattern") ?? throw new InvalidOperationException("LEGACY_PATTERN_MISSING");
+            string Value(string name) => pattern.Element(name)?.Value ?? throw new InvalidOperationException("LEGACY_PATTERN_FIELD_MISSING:" + name);
+            var plugins = data.Elements("plugin").Select((plugin, index) => new LegacyPluginDefinition(
+                plugin.Element("id")?.Value ?? throw new InvalidOperationException("LEGACY_PLUGIN_ID_MISSING"),
+                plugin.Element("renewal")?.Value ?? throw new InvalidOperationException("LEGACY_RENEWAL_MISSING"),
+                plugin.Element("catalog")?.Value ?? throw new InvalidOperationException("LEGACY_CATALOG_MISSING"),
+                plugin.Element("install")?.Value ?? throw new InvalidOperationException("LEGACY_INSTALL_MISSING"), index)).ToArray();
+            return new LegacyProductPattern(Value("name"), Value("filter"), Value("roster"), plugins);
+        }).ToArray();
+        return new(path.Element("help")?.Value ?? throw new InvalidOperationException("LEGACY_HELP_MISSING"), path.Element("care")?.Value ?? throw new InvalidOperationException("LEGACY_CARE_MISSING"), patterns);
+    }
+
+    public LegacyDownloadSelection ParseDownloadList(string xml)
+    {
+        using var reader = XmlReader.Create(new StringReader(xml), XmlSettings); var root = XDocument.Load(reader).Root;
+        if (root?.Name != "root") throw new InvalidOperationException("LEGACY_DOWNLOAD_LIST_INVALID");
+        var ids = root.Elements("id").Select(x => x.Value.Trim()).ToArray();
+        if (ids.Length == 0 || ids.Any(string.IsNullOrWhiteSpace) || ids.GroupBy(x => x, StringComparer.OrdinalIgnoreCase).Any(x => x.Count() > 1))
+            throw new InvalidOperationException("LEGACY_DOWNLOAD_SELECTION_INVALID");
+        return new(ids);
+    }
+
+    public IReadOnlyList<PackageRequirement> Join(LegacyProductPattern pattern, LegacyDownloadSelection selection, LegacyCompatibilityOverlay overlay)
+    {
+        var result = new List<PackageRequirement>();
+        foreach (var id in selection.PluginIds)
+        {
+            var definition = pattern.Plugins.Where(x => string.Equals(x.Id, id, StringComparison.OrdinalIgnoreCase)).ToArray();
+            if (definition.Length == 0) throw new InvalidOperationException("LEGACY_PLUGIN_ID_NOT_DEFINED");
+            if (definition.Length > 1) throw new InvalidOperationException("AMBIGUOUS_LEGACY_PLUGIN_DEFINITION");
+            var mapping = overlay.Plugins.Where(x => string.Equals(x.LegacyId, id, StringComparison.OrdinalIgnoreCase)).ToArray();
+            if (mapping.Length == 0) throw new InvalidOperationException("LEGACY_MAPPING_NOT_FOUND");
+            if (mapping.Length > 1) throw new InvalidOperationException("LEGACY_MAPPING_DUPLICATE");
+            result.Add(new(mapping[0].PackageId, overlay.Product, overlay.ProductYear, overlay.Architecture, mapping[0].Channel, mapping[0].Version, overlay.MappingId, overlay.AllowOfflineFallback));
+        }
+        return result;
+    }
+}
diff --git a/tests/Launcher.Next.Tests/RosterAdaptersTests.cs b/tests/Launcher.Next.Tests/RosterAdaptersTests.cs
index 129e760..5be904b 100644
--- a/tests/Launcher.Next.Tests/RosterAdaptersTests.cs
+++ b/tests/Launcher.Next.Tests/RosterAdaptersTests.cs
@@ -31,6 +31,24 @@ public sealed class RosterAdaptersTests
         Assert.False(selected.Roster.Packages[1].Enabled);
     }
 
+    [Fact]
+    public void LegacySettingsAndDownloadList_JoinOnlyThroughExplicitOverlay()
+    {
+        const string settings = "<root><path><help>h</help><care>c</care></path><data><pattern><name>Plant</name><filter>*.dwg</filter><roster>r</roster></pattern><plugin><id>legacy-a</id><renewal>x</renewal><catalog>cat</catalog><install>load</install></plugin></data></root>";
+        const string selection = "<root><id>legacy-a</id></root>";
+        var adapter = new LegacyConfigurationAdapter();
+        var parsed = adapter.ParseSettings(settings);
+        var requirements = adapter.Join(parsed.Patterns[0], adapter.ParseDownloadList(selection), new("map-a", "Plant3D", 2026, "x64", false, [new("legacy-a", "PHIM.A", "1.0.0", "pilot")]));
+        Assert.Single(requirements); Assert.Equal("PHIM.A", requirements[0].PackageId);
+    }
+
+    [Fact]
+    public void LegacyDownloadList_DoesNotInventPluginMetadata()
+    {
+        var selection = new LegacyConfigurationAdapter().ParseDownloadList("<root><id>legacy-a</id></root>");
+        Assert.Equal(["legacy-a"], selection.PluginIds);
+    }
+
     [Fact]
     public void ProjectRoster_HasPriorityOverLegacy()
     {