feat(dto): add generated contract nullability

docs/topics/dto-shapes-and-read-models.md

@@ -57,3 +57,9 @@ That keeps the generated-shape pipeline usable in larger solutions where multipl
 Coalesce can now generate auto-projected read shapes for scenarios where the response model is intentionally smaller or differently organized than the backing entity.
 
 This is the layer that makes richer read DTOs practical without forcing every read endpoint to rely on hand-written projection types.
+
+## Generated contract shapes can transform nullability per output
+
+Generated contract shapes are not limited to a single nullability policy. A single source type can now describe stricter read-facing contracts and more permissive write- or patch-facing contracts from the same model.
+
+That keeps generated interfaces and DTO classes aligned with their actual API semantics instead of forcing one nullability story onto every generated output.

src/IntelliTect.Coalesce.CodeGeneration.Tests/GeneratedContractShapeGenerationTests.cs

@@ -0,0 +1,124 @@
+using IntelliTect.Coalesce.CodeGeneration.Api.Generators;
+using IntelliTect.Coalesce.CodeGeneration.Generation;
+using IntelliTect.Coalesce.Testing;
+using IntelliTect.Coalesce.Testing.Util;
+using IntelliTect.Coalesce.TypeDefinition;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Text;
+using Microsoft.Extensions.DependencyInjection;
+using System.Reflection;
+
+namespace IntelliTect.Coalesce.CodeGeneration.Tests;
+
+public class GeneratedContractShapeGenerationTests : CodeGenTestBase
+{
+    [Test]
+    public async Task GeneratedContracts_SupportShapeLevelNullabilityTransforms()
+    {
+        var executor = BuildExecutor();
+        var generatorServices = executor.ServiceProvider.GetRequiredService<GeneratorServices>();
+
+        var compilation = ReflectionRepositoryFactory.GetCompilation(ReflectionRepositoryFactory.ModelSyntaxTrees);
+        var sourceType = compilation.GetTypeByMetadataName(
+            "IntelliTect.Coalesce.Testing.TargetClasses.TestDbContext.GeneratedContractShapeEntity");
+        await Assert.That(sourceType).IsNotNull();
+        var shapeSourceType = sourceType!;
+
+        var getShapes = typeof(GeneratedContracts)
+            .GetMethod("GetShapes", BindingFlags.NonPublic | BindingFlags.Static)!;
+        var resolveProperties = typeof(GeneratedContracts)
+            .GetMethod("ResolveProperties", BindingFlags.NonPublic | BindingFlags.Static)!;
+
+        var shapes = ((IEnumerable<GeneratedContracts.ContractShape>)getShapes.Invoke(null, [shapeSourceType])!)
+            .ToDictionary(shape => shape.TypeName, StringComparer.Ordinal);
+
+        async Task<string> RenderShape(string typeName)
+        {
+            var shape = shapes[typeName];
+            var properties = (IReadOnlyList<GeneratedContracts.ContractPropertyModel>)resolveProperties.Invoke(null, [shapeSourceType, shape])!;
+            var file = new GeneratedContractFile(generatorServices)
+            {
+                Model = new GeneratedContracts.GeneratedContractFileModel(
+                    shape,
+                    properties,
+                    shapeSourceType.ToDisplayString(SymbolTypeViewModel.DefaultDisplayFormat)),
+            };
+
+            return await file.BuildOutputAsync();
+        }
+
+        var detailsContents = await RenderShape("IGeneratedContractShapeDetails");
+        var writeBaseContents = await RenderShape("IGeneratedContractShapeWriteBase");
+        var createContents = await RenderShape("GeneratedContractShapeCreate");
+        var patchContents = await RenderShape("IGeneratedContractShapePatch");
+
+        await Assert.That(detailsContents.Contains("string Description { get; }")).IsTrue();
+        await Assert.That(detailsContents.Contains("string Name { get; }")).IsTrue();
+
+        await Assert.That(writeBaseContents.Contains("string Name { get; }")).IsTrue();
+        await Assert.That(writeBaseContents.Contains("string? Description { get; }")).IsTrue();
+        await Assert.That(writeBaseContents.Contains("string? OptionalNotes { get; }")).IsTrue();
+        await Assert.That(writeBaseContents.Contains("global::System.Collections.Generic.List<string>? Tags { get; }")).IsTrue();
+        await Assert.That(writeBaseContents.Contains("int Count { get; }")).IsTrue();
+
+        await Assert.That(createContents.Contains("public required string Name { get; set; }")).IsTrue();
+        await Assert.That(createContents.Contains("public string? Description { get; set; }")).IsTrue();
+        await Assert.That(createContents.Contains("public global::System.Collections.Generic.List<string>? Tags { get; set; }")).IsTrue();
+
+        await Assert.That(patchContents.Contains("string? Name { get; }")).IsTrue();
+        await Assert.That(patchContents.Contains("int? Count { get; }")).IsTrue();
+        await Assert.That(patchContents.Contains("bool? Enabled { get; }")).IsTrue();
+        await Assert.That(patchContents.Contains("global::System.DateTime? EffectiveOn { get; }")).IsTrue();
+
+        ReflectionRepositoryFactory.GetCompilation(
+            [
+                CSharpSyntaxTree.ParseText(SourceText.From(detailsContents), path: "IGeneratedContractShapeDetails.g.cs"),
+                CSharpSyntaxTree.ParseText(SourceText.From(writeBaseContents), path: "IGeneratedContractShapeWriteBase.g.cs"),
+                CSharpSyntaxTree.ParseText(SourceText.From(createContents), path: "GeneratedContractShapeCreate.g.cs"),
+                CSharpSyntaxTree.ParseText(SourceText.From(patchContents), path: "IGeneratedContractShapePatch.g.cs"),
+            ],
+            assertSuccess: true);
+    }
+
+    [Test]
+    public async Task GeneratedContracts_PropagateDtoSourceAttributesToClassOutputs()
+    {
+        var executor = BuildExecutor();
+        var generatorServices = executor.ServiceProvider.GetRequiredService<GeneratorServices>();
+
+        var compilation = ReflectionRepositoryFactory.GetCompilation(ReflectionRepositoryFactory.ModelSyntaxTrees);
+        var sourceType = compilation.GetTypeByMetadataName(
+            "IntelliTect.Coalesce.Testing.TargetClasses.TestDbContext.GeneratedContractShapeProjectionSource");
+        await Assert.That(sourceType).IsNotNull();
+        var shapeSourceType = sourceType!;
+
+        var getShapes = typeof(GeneratedContracts)
+            .GetMethod("GetShapes", BindingFlags.NonPublic | BindingFlags.Static)!;
+        var resolveProperties = typeof(GeneratedContracts)
+            .GetMethod("ResolveProperties", BindingFlags.NonPublic | BindingFlags.Static)!;
+
+        var shape = ((IEnumerable<GeneratedContracts.ContractShape>)getShapes.Invoke(null, [shapeSourceType])!)
+            .Single(candidate => candidate.TypeName == "GeneratedContractShapeProjectionSpec");
+
+        var properties = (IReadOnlyList<GeneratedContracts.ContractPropertyModel>)resolveProperties.Invoke(null, [shapeSourceType, shape])!;
+        var file = new GeneratedContractFile(generatorServices)
+        {
+            Model = new GeneratedContracts.GeneratedContractFileModel(
+                shape,
+                properties,
+                shapeSourceType.ToDisplayString(SymbolTypeViewModel.DefaultDisplayFormat)),
+        };
+
+        var contents = await file.BuildOutputAsync();
+
+        await Assert.That(contents.Contains("[global::IntelliTect.Coalesce.DataAnnotations.DtoSource(\"OwnerTenant.Name\")]")).IsTrue();
+        await Assert.That(contents.Contains("[global::IntelliTect.Coalesce.DataAnnotations.DtoSource(\"Children\", OrderBy = \"Name\", OrderByDirection = global::IntelliTect.Coalesce.DataAnnotations.DefaultOrderByAttribute.OrderByDirections.Descending)]")).IsTrue();
+        await Assert.That(contents.Contains("public string? TenantName { get; set; }")).IsTrue();
+        await Assert.That(contents.Contains("public global::System.Collections.Generic.List<string> OrderedChildren { get; set; } = [];")).IsTrue();
+
+        ReflectionRepositoryFactory.GetCompilation(
+            [CSharpSyntaxTree.ParseText(SourceText.From(contents), path: "GeneratedContractShapeProjectionSpec.g.cs")],
+            assertSuccess: true);
+    }
+}