Add contract-derived OpenAPI operation metadata

docs/mediator-framework/design.md

@@ -68,6 +68,8 @@ request type. Each transport is opt-in and declared independently:
   code-first gRPC method; `[ServiceGroup("Orders")]` groups the service.
 - `[RebusMessage(OwnerQueue = "orders")]` — expose as a Rebus message and,
   when an owner is declared, contribute a type-based outbound route.
+- `[ApiTag("Orders")]` — override the namespace-derived OpenAPI tag and the
+  gRPC service-group fallback for the contract.
 
 Generated HTTP endpoints require authorization by default. Set `Policy` on
 `[HttpEndpoint]` to select a named policy, or set `AllowAnonymous = true` for
@@ -80,7 +82,8 @@ Generator contract errors are reported at the transport attribute location:
 `ARKMF010` (unknown HTTP verb), `ARKMF011` (unsupported handler kind),
 `ARKMF012` (missing route property), `ARKMF013` (invalid HTTP contract shape),
 `ARKMF014` (duplicate Rebus registration), and `ARKMF015` (conflicting Rebus
-owner queue). Invalid contracts are not emitted.
+owner queue), and `ARKMF016` (duplicate OpenAPI operation name within an API
+version). Invalid contracts are not emitted.
 
 HTTP binding treats the request as an **envelope** whose members may combine
 route, query and body sources (see *HTTP binding* below). These attributes are

docs/mediator-framework/progress/tasks.md

@@ -339,7 +339,7 @@ Each item has a self-contained task document under
 [`tasks/`](tasks/README.md); the acceptance criteria live there and are the
 authoritative ones.
 
-- [ ] **T12.1** OpenAPI tags and operation names from the contract
+- [x] **T12.1** OpenAPI tags and operation names from the contract
   ([NET-06](tasks/aspnetcore/NET-06-openapi-tags-operation-names.md)).
   - *Accept:* every generated operation carries a namespace-derived tag
     (overridable with `[ApiTag]`) and a unique, contract-derived `operationId`;

docs/mediator-framework/progress/tasks/README.md

@@ -110,7 +110,7 @@ recent security commits `8502585`, `fd4d600`, `938567d`, and `c0fc361`.
    [ ] [SMP-06](sample-parity/SMP-06-misc-parity.md)
    [ ] [NET-01](aspnetcore/NET-01-openapi-xml-docs.md)
 7. Scope extension (D8) — wire-shape items first, documentation last:
-   [ ] [NET-06](aspnetcore/NET-06-openapi-tags-operation-names.md)
+   [x] [NET-06](aspnetcore/NET-06-openapi-tags-operation-names.md)
    [ ] [FW-05](framework/FW-05-standard-problem-responses.md)
    [ ] [FW-06](framework/FW-06-async-enumerable-streaming.md)
    [ ] [FW-07](framework/FW-07-multifile-uploads.md)

docs/mediator-framework/progress/tasks/aspnetcore/NET-06-openapi-tags-operation-names.md

@@ -72,11 +72,11 @@ See `docs/mediator-framework/design.md` → *OpenAPI operation grouping, naming
 
 ## Acceptance
 
-- [ ] `ApiTagAttribute` exists in `Ark.Tools.MediatorFramework` with XML docs.
-- [ ] Generated endpoints emit `.WithTags(...)` and `.WithName(...)`; snapshots updated.
-- [ ] `operationId` is unique within each versioned document (tested).
-- [ ] Duplicate operation names produce a documented generator diagnostic (tested).
-- [ ] gRPC service grouping falls back to `[ApiTag]`; explicit `[ServiceGroup]` still wins (tested).
-- [ ] `design.md` documents the defaults, the override and the new diagnostic id.
-- [ ] `dotnet build Ark.Tools.slnx --configuration Debug` succeeds with zero warnings.
-- [ ] `dotnet test Ark.Tools.slnx --no-build --configuration Debug --minimum-expected-tests 1` passes.
+- [x] `ApiTagAttribute` exists in `Ark.Tools.MediatorFramework` with XML docs.
+- [x] Generated endpoints emit `.WithTags(...)` and `.WithName(...)`; snapshots updated.
+- [x] `operationId` is unique within each versioned document (tested).
+- [x] Duplicate operation names produce a documented generator diagnostic (tested).
+- [x] gRPC service grouping falls back to `[ApiTag]`; explicit `[ServiceGroup]` still wins (tested).
+- [x] `design.md` documents the defaults, the override and the new diagnostic id.
+- [x] `dotnet build Ark.Tools.slnx --configuration Debug` succeeds with zero warnings.
+- [x] `dotnet test Ark.Tools.slnx --no-build --configuration Debug --minimum-expected-tests 1` passes.

samples/Ark.MediatorFramework.Sample/src/Ark.MediatorFramework.Sample.Application/GreetingContracts.cs

@@ -97,6 +97,7 @@ public sealed record CreateGreetingRequest : IRequest<GreetingResponse>
 }
 
 /// <summary>HTTP-only request that publishes work to Rebus and returns immediately.</summary>
+[ApiTag("Greetings")]
 [HttpEndpoint("POST", "/api/v{version}/greetings/compose")]
 public sealed record ComposeGreetingRequest : IRequest<ComposeGreetingResponse>
 {

src/mediator-framework/Ark.Tools.MediatorFramework.Grpc.Generators/GrpcEndpointGenerator.cs

@@ -27,6 +27,7 @@ public sealed class ArkGrpcEndpointGenerator : IIncrementalGenerator
     {
         private const string GrpcMethodAttribute = "Ark.MediatorFramework.GrpcMethodAttribute";
         private const string ServiceGroupAttribute = "Ark.MediatorFramework.ServiceGroupAttribute";
+        private const string ApiTagAttribute = "Ark.MediatorFramework.ApiTagAttribute";
         private const string ServerSetAttribute = "Ark.MediatorFramework.ServerSetAttribute";
         private const string ArkAttachment = "Ark.MediatorFramework.IArkAttachment";
 
@@ -62,12 +63,13 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             var type = (INamedTypeSymbol)context.TargetSymbol;
             var grpc = context.Attributes[0];
             var serviceGroupAttribute = context.SemanticModel.Compilation.GetTypeByMetadataName(ServiceGroupAttribute);
+            var apiTagAttribute = context.SemanticModel.Compilation.GetTypeByMetadataName(ApiTagAttribute);
             var attachmentType = context.SemanticModel.Compilation.GetTypeByMetadataName(ArkAttachment);
             var serviceGroup = serviceGroupAttribute is null
                 ? null
                 : type.GetAttributes().FirstOrDefault(
                     attribute => SymbolEqualityComparer.Default.Equals(attribute.AttributeClass, serviceGroupAttribute));
-            return Extract(type, grpc, serviceGroup, attachmentType);
+            return Extract(type, grpc, serviceGroup, apiTagAttribute, attachmentType);
         }
 
         private static string? GetAssemblyName(GeneratorSyntaxContext context, string methodName)
@@ -88,6 +90,7 @@ private static ImmutableArray<EndpointModel> GetReferencedEndpoints(
         {
             var grpcAttr = compilation.GetTypeByMetadataName(GrpcMethodAttribute);
             var serviceGroupAttr = compilation.GetTypeByMetadataName(ServiceGroupAttribute);
+            var apiTagAttr = compilation.GetTypeByMetadataName(ApiTagAttribute);
             var attachmentType = compilation.GetTypeByMetadataName(ArkAttachment);
             if (grpcAttr is null)
                 return ImmutableArray<EndpointModel>.Empty;
@@ -106,7 +109,7 @@ private static ImmutableArray<EndpointModel> GetReferencedEndpoints(
                         continue;
 
                     var serviceGroup = attrs.FirstOrDefault(a => SymbolEqualityComparer.Default.Equals(a.AttributeClass, serviceGroupAttr));
-                    var model = Extract(type, grpc, serviceGroup, attachmentType);
+                    var model = Extract(type, grpc, serviceGroup, apiTagAttr, attachmentType);
                     if (model is not null)
                         builder.Add(model.Value);
                 }
@@ -157,6 +160,7 @@ private static IEnumerable<INamedTypeSymbol> _allTypes(INamespaceSymbol ns)
             INamedTypeSymbol type,
             AttributeData grpc,
             AttributeData? serviceGroup,
+            INamedTypeSymbol? apiTagAttribute,
             INamedTypeSymbol? attachmentType)
         {
             string? response = null;
@@ -199,7 +203,18 @@ private static IEnumerable<INamedTypeSymbol> _allTypes(INamespaceSymbol ns)
             var grpcMethod = grpc.ConstructorArguments.FirstOrDefault().Value as string ?? type.Name;
             var grpcIntroducedIn = NamedInt(grpc, "IntroducedIn", 1);
             var grpcRetiredIn = NamedInt(grpc, "RetiredIn", 0);
-            var group = serviceGroup?.ConstructorArguments.FirstOrDefault().Value as string ?? "Ark";
+            var apiTag = apiTagAttribute is null
+                ? null
+                : type.GetAttributes()
+                    .Where(attribute => SymbolEqualityComparer.Default.Equals(attribute.AttributeClass, apiTagAttribute))
+                    .Select(attribute => attribute.ConstructorArguments.FirstOrDefault().Value as string)
+                    .FirstOrDefault(value => !string.IsNullOrWhiteSpace(value));
+            var defaultGroup = type.ContainingNamespace is { IsGlobalNamespace: false } ns
+                ? ns.ToDisplayString().Split('.').Last()
+                : "Ark";
+            var group = serviceGroup?.ConstructorArguments.FirstOrDefault().Value as string
+                ?? apiTag
+                ?? defaultGroup;
 
             return new EndpointModel(
                 type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat),