[codex] Remove MergePatchTarget attribute

README.md

@@ -122,6 +122,10 @@ The target type lets MergePatchDto generate typed mapping:
 patch.ApplyTo(person);
 ```
 
+If the same patch shape should apply to multiple concrete types, target a
+shared interface. Generated `ApplyTo` accepts the interface and maps only
+members declared on that interface.
+
 It does not mean every property on `Person` is patchable. The DTO remains the boundary.
 
 ## Manual Updates
@@ -174,9 +178,7 @@ If a target property should not be patchable, leave it off the DTO.
   deserialized and presence-tracked, but excluded from generated `ApplyTo`.
 - `[PatchUsing(nameof(Method))]` calls custom domain logic when the patch
   property was provided.
-- `[MergePatchTarget(typeof(OtherTarget))]` adds another typed `ApplyTo`
-  overload.
-- Targets can be interfaces. In that case, generated `ApplyTo` accepts the interface and maps only members declared on that interface.
+- Targets can be interfaces.
 
 ```csharp
 [MergePatch(typeof(Person))]

src/MergePatchDto.Generators/MergePatchGenerator.cs

@@ -12,7 +12,6 @@ namespace MergePatchDto.Generators
     public sealed class MergePatchGenerator : IIncrementalGenerator
     {
         private const string MergePatchAttributeName = "MergePatch.MergePatchAttribute";
-        private const string MergePatchTargetAttributeName = "MergePatch.MergePatchTargetAttribute";
         private const string PatchIgnoreAttributeName = "MergePatch.PatchIgnoreAttribute";
         private const string PatchToAttributeName = "MergePatch.PatchToAttribute";
         private const string PatchUsingAttributeName = "MergePatch.PatchUsingAttribute";
@@ -382,14 +381,9 @@ private static EffectiveVisibility Min(EffectiveVisibility left, EffectiveVisibi
 
             var patchDtoAttribute = context.Attributes.FirstOrDefault(attribute => IsAttribute(attribute, MergePatchAttributeName));
 
-            var targetAttributes = typeSymbol
-                .GetAttributes()
-                .Where(attribute => IsAttribute(attribute, MergePatchTargetAttributeName))
-                .ToArray();
-
-            var targetDeclarations = targetAttributes
-                .Concat(patchDtoAttribute == null ? Enumerable.Empty<AttributeData>() : new[] { patchDtoAttribute })
-                .ToArray();
+            var targetDeclarations = patchDtoAttribute == null
+                ? Enumerable.Empty<AttributeData>()
+                : new[] { patchDtoAttribute };
 
             var targets = targetDeclarations
                 .Select(BuildTargetModel)

tests/MergePatchDto.Tests/ApplyToConventionTests.cs

@@ -40,20 +40,6 @@ public void ApplyToDoesNotCallSetterForMissingProperty()
         Assert.Equal(before, target.NameSetCount);
     }
 
-    [Fact]
-    public void PatchDtoCanGenerateMultipleTargetOverloads()
-    {
-        var patch = JsonSerializer.Deserialize<MultiTargetPatch>("""{ "Name": "Draft" }""")!;
-        var documentTarget = new Document();
-        var draftTarget = new DocumentDraft();
-
-        patch.ApplyTo(documentTarget);
-        patch.ApplyTo(draftTarget);
-
-        Assert.Equal("Draft", documentTarget.Name);
-        Assert.Equal("Draft", draftTarget.Name);
-    }
-
     [Fact]
     public void PatchDtoCanTargetInterfaceImplementedByMultipleClasses()
     {

tests/MergePatchDto.Tests/DiagnosticsTests.cs

@@ -96,8 +96,7 @@ public void ReportsErrorWhenPatchTargetCannotBeResolved()
             """
             using MergePatch;
 
-            [MergePatch]
-            [MergePatchTarget(typeof(MissingTarget))]
+            [MergePatch(typeof(MissingTarget))]
             public partial class Patch
             {
                 public string? Name { get; set; }
@@ -132,32 +131,6 @@ public partial class Patch
             !diagnostic.Id.StartsWith("MPD", StringComparison.Ordinal));
     }
 
-    [Fact]
-    public void ReportsErrorWhenAdditionalPatchTargetIsOpenGeneric()
-    {
-        var diagnostics = DiagnosticTestHelper.GetAllDiagnostics(
-            """
-            using MergePatch;
-
-            public class Box<T>
-            {
-                public string? Name { get; set; }
-            }
-
-            [MergePatch]
-            [MergePatchTarget(typeof(Box<>))]
-            public partial class Patch
-            {
-                public string? Name { get; set; }
-            }
-            """);
-
-        Assert.Contains(diagnostics, diagnostic => diagnostic.Id == "MPD018" && diagnostic.Severity == DiagnosticSeverity.Error);
-        Assert.DoesNotContain(diagnostics, diagnostic =>
-            diagnostic.Severity == DiagnosticSeverity.Error &&
-            !diagnostic.Id.StartsWith("MPD", StringComparison.Ordinal));
-    }
-
     [Fact]
     public void ReportsErrorWhenPatchTargetIsLessAccessibleThanPublicPatchDto()
     {

tests/MergePatchDto.Tests/TestModels.cs

@@ -71,11 +71,6 @@ public void SetPriority(int? value)
     }
 }
 
-public sealed class DocumentDraft
-{
-    public string? Name { get; set; }
-}
-
 public interface INamedResource
 {
     string? Name { get; set; }
@@ -120,14 +115,6 @@ private static void ApplyPriority(Document target, int? value)
     }
 }
 
-[MergePatch]
-[MergePatchTarget(typeof(Document))]
-[MergePatchTarget(typeof(DocumentDraft))]
-public partial class MultiTargetPatch
-{
-    public string? Name { get; set; }
-}
-
 [MergePatch(typeof(INamedResource))]
 public partial class InterfaceTargetPatch
 {