From 6ed8048f8120da641171e127d777cb56989d3429 Mon Sep 17 00:00:00 2001
From: Jonathan Cardenas <JonathanCrd@users.noreply.github.com>
Date: Tue, 19 May 2026 15:32:08 -0700
Subject: [PATCH 1/2] fix: [http-client-csharp] wrap BinaryData with
 BinaryContent.Create in MethodParameterSegments navigation

When MethodParameterSegments navigation resolves to a BinaryData property,
the expression was passed directly as a BinaryContent protocol argument
without wrapping. This caused a CS1503 compilation error.

Wrap the resolved property expression with RequestContentApiSnippets.Create()
when the protocol parameter is a content parameter.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../Providers/ScmMethodProviderCollection.cs  | 12 ++++-
 .../ScmMethodProviderCollectionTests.cs       | 45 +++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs
index c85805768e9..fb2ad27ddd8 100644
--- a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs
+++ b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs
@@ -804,7 +804,17 @@ private IReadOnlyList<ValueExpression> GetProtocolMethodArguments(Dictionary<str
                     if (ScmCodeModelGenerator.Instance.TypeFactory.CSharpTypeMap.TryGetValue(convenienceParam.Type, out var typeProvider) &&
                         typeProvider is ModelProvider paramModel)
                     {
-                        AddArgument(protocolParam, paramModel.GetPropertyExpression(convenienceParam, propertySegments));
+                        var propertyExpression = paramModel.GetPropertyExpression(convenienceParam, propertySegments);
+                        // When the protocol parameter expects BinaryContent (i.e., it's a content parameter),
+                        // wrap the resolved BinaryData property expression with BinaryContent.Create().
+                        if (protocolParam.IsContentParameter)
+                        {
+                            AddArgument(protocolParam, RequestContentApiSnippets.Create(propertyExpression));
+                        }
+                        else
+                        {
+                            AddArgument(protocolParam, propertyExpression);
+                        }
                     }
                 }
                 else
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ScmMethodProviderCollectionTests.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ScmMethodProviderCollectionTests.cs
index b54ece36bd0..af9750434d7 100644
--- a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ScmMethodProviderCollectionTests.cs
+++ b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ScmMethodProviderCollectionTests.cs
@@ -1617,6 +1617,51 @@ public async Task MethodParameterSegments_UpdateMethod_SetsSegments()
             Assert.AreEqual("param2", param.MethodParameterSegments[1].Name);
         }
 
+        [Test]
+        public async Task MethodParameterSegments_BodyBinaryDataProperty_WrapsWithBinaryContentCreate()
+        {
+            // Test scenario: When a body parameter navigates to a BinaryData property via MethodParameterSegments,
+            // the convenience method should wrap the expression with BinaryContent.Create().
+            var streamModel = InputFactory.Model(
+                "StreamModel",
+                properties:
+                [
+                    InputFactory.Property("body", InputPrimitiveType.Base64, isRequired: true),
+                ]);
+
+            var bodyParam = InputFactory.BodyParameter("body", InputPrimitiveType.Base64, isRequired: true,
+                contentTypes: ["application/jsonl"], defaultContentType: "application/jsonl");
+            bodyParam.Update(methodParameterSegments: [
+                InputFactory.MethodParameter("stream", streamModel, isRequired: true, location: InputRequestLocation.None),
+                InputFactory.MethodParameter("body", InputPrimitiveType.Base64, isRequired: true)
+            ]);
+
+            var serviceMethod = InputFactory.BasicServiceMethod(
+                "send",
+                InputFactory.Operation(
+                    "send",
+                    parameters: [bodyParam],
+                    requestMediaTypes: ["application/jsonl"],
+                    responses: [InputFactory.OperationResponse([204])]),
+                parameters: [InputFactory.MethodParameter("stream", streamModel, isRequired: true, location: InputRequestLocation.None)]);
+
+            var inputClient = InputFactory.Client("TestClient", methods: [serviceMethod]);
+            await MockHelpers.LoadMockGeneratorAsync(clients: () => [inputClient], inputModels: () => [streamModel]);
+
+            var client = ScmCodeModelGenerator.Instance.TypeFactory.CreateClient(inputClient);
+            Assert.IsNotNull(client);
+
+            var methodCollection = new ScmMethodProviderCollection(serviceMethod, client!);
+            var convenienceMethod = methodCollection.FirstOrDefault(
+                m => m.Signature.Parameters.Any(p => p.Name == "stream") && m.Signature.Name == "Send");
+            Assert.IsNotNull(convenienceMethod);
+
+            var methodBody = convenienceMethod!.BodyStatements!.ToDisplayString();
+            // Verify that BinaryContent.Create() wraps the property access
+            Assert.IsTrue(methodBody.Contains("BinaryContent.Create(stream.Body)"),
+                $"Expected 'BinaryContent.Create(stream.Body)' in method body but got: {methodBody}");
+        }
+
         [Test]
         public async Task MissingOperationParamsResultInNamedArgsForSubsequent()
         {

From e5cca811526c466af73de50fb8a90993b448224d Mon Sep 17 00:00:00 2001
From: Jonathan Cardenas <JonathanCrd@users.noreply.github.com>
Date: Tue, 19 May 2026 15:32:16 -0700
Subject: [PATCH 2/2] chore: [http-client-csharp] regenerate Sample-TypeSpec
 after BinaryContent fix

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs b/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs
index 659c42158d9..793f3eb27a1 100644
--- a/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs
+++ b/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs
@@ -334,7 +334,7 @@ public virtual ClientResult<RoundTripModel> NoContentType(Wrapper info, Cancella
         {
             Argument.AssertNotNull(info, nameof(info));
 
-            ClientResult result = NoContentType(info.P2, info.P1, info.Action, cancellationToken.ToRequestOptions());
+            ClientResult result = NoContentType(info.P2, info.P1, BinaryContent.Create(info.Action), cancellationToken.ToRequestOptions());
             return ClientResult.FromValue((RoundTripModel)result, result.GetRawResponse());
         }
 
@@ -347,7 +347,7 @@ public virtual async Task<ClientResult<RoundTripModel>> NoContentTypeAsync(Wrapp
         {
             Argument.AssertNotNull(info, nameof(info));
 
-            ClientResult result = await NoContentTypeAsync(info.P2, info.P1, info.Action, cancellationToken.ToRequestOptions()).ConfigureAwait(false);
+            ClientResult result = await NoContentTypeAsync(info.P2, info.P1, BinaryContent.Create(info.Action), cancellationToken.ToRequestOptions()).ConfigureAwait(false);
             return ClientResult.FromValue((RoundTripModel)result, result.GetRawResponse());
         }