Honor [Consumes] / IAcceptsMetadata on form endpoints

src/Http/Wolverine.Http.Tests/using_form_parameters.cs

@@ -536,4 +536,22 @@ public void trouble_shoot_form_matching()
         var variable = chain.TryFindOrCreateFormValue(parameter);
         variable!.Creator.ShouldBeOfType<ParsedArrayFormValue>();
     }
+
+    [Fact]
+    public void form_endpoints_honor_consumes_metadata_for_supported_request_formats()
+    {
+        // fillRequestType only seeds SupportedRequestFormats from
+        // IAcceptsMetadata when the endpoint has a body request type and is
+        // not a form endpoint. Form endpoints used to fall through and rely
+        // on ASP.NET Core OpenAPI's "application/x-www-form-urlencoded"
+        // default, which silently dropped [Consumes("multipart/form-data")]
+        // and caused generated clients (Orval, NSwag) to emit URLSearchParams
+        // bodies instead of multipart for file-upload endpoints.
+        var chain = HttpChains.ChainFor("POST", "/form/multipart-consumes");
+        var apiDescription = chain!.CreateApiDescription("POST");
+
+        apiDescription.SupportedRequestFormats
+            .Select(f => f.MediaType)
+            .ShouldContain("multipart/form-data");
+    }
 }

src/Http/Wolverine.Http/HttpChain.ApiDescription.cs

@@ -158,6 +158,29 @@ public ApiDescription CreateApiDescription(string httpMethod)
             apiDescription.ParameterDescriptions.Add(parameterDescription);
         }
 
+        // fillRequestType only honors [Consumes] / IAcceptsMetadata for body
+        // endpoints (HasRequestType && !IsFormData). Without this, form
+        // endpoints fall through and ASP.NET Core OpenAPI's GetFormRequestBody
+        // defaults SupportedRequestFormats to "application/x-www-form-urlencoded"
+        // — silently dropping [Consumes("multipart/form-data")] on file-upload
+        // endpoints and causing client generators (Orval, NSwag, Kiota) to emit
+        // URLSearchParams bodies instead of multipart.
+        if (apiDescription.SupportedRequestFormats.Count == 0 &&
+            apiDescription.ParameterDescriptions.Any(p =>
+                p.Source == BindingSource.Form || p.Source == BindingSource.FormFile))
+        {
+            foreach (var metadata in Endpoint!.Metadata.OfType<IAcceptsMetadata>())
+            {
+                foreach (var contentType in metadata.ContentTypes)
+                {
+                    apiDescription.SupportedRequestFormats.Add(new ApiRequestFormat
+                    {
+                        MediaType = contentType
+                    });
+                }
+            }
+        }
+
         return apiDescription;
     }
 

src/Http/WolverineWebApi/Forms/FormEndpoints.cs

@@ -111,6 +111,10 @@ public static string PostWithFiles([FromForm] FormWithFiles form)
     {
         return $"{form.Name}|{form.Files?.Count}";
     }
+
+    [WolverinePost("/form/multipart-consumes")]
+    [Consumes("multipart/form-data")]
+    public static string MultipartConsumes([FromForm] string value) => value ?? "";
 }
 
 public class FormWithFile