fix(csharp): Remove delay on HTTP Streaming when response is not fully finished. (#9983)

Use HttpCompletionOption.ResponseHeadersRead in RawClient sendAsync

Author: fearthecowboy

generators/csharp/base/src/asIs/RawClient.Template.cs

@@ -125,7 +125,7 @@ CancellationToken cancellationToken
     {
         var httpClient = options?.HttpClient ?? Options.HttpClient;
         var maxRetries = options?.MaxRetries ?? Options.MaxRetries;
-        var response = await httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
+        var response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
         var isRetryableContent = IsRetryableContent(request);
 
         if (!isRetryableContent)
@@ -144,7 +144,7 @@ CancellationToken cancellationToken
             await SystemTask.Delay(delayMs, cancellationToken).ConfigureAwait(false);
             using var retryRequest = await CloneRequestAsync(request).ConfigureAwait(false);
             response = await httpClient
-                .SendAsync(retryRequest, cancellationToken)
+                .SendAsync(retryRequest, HttpCompletionOption.ResponseHeadersRead, cancellationToken)
                 .ConfigureAwait(false);
         }
 

generators/csharp/sdk/versions.yml

@@ -1,4 +1,12 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
+- version: 2.4.4
+  changelogEntry:
+    - type: fix
+      summary: |
+        When sending the HTTP request, allow the response to start processing before the entire body is read.
+  createdAt: "2025-10-20"
+  irVersion: 61
+
 - version: 2.4.3
   changelogEntry:
     - type: fix