Stream the answers again whenever tools are in play (#986)

app/MindWork AI Studio/Provider/Anthropic/ProviderAnthropic.cs

@@ -75,8 +75,8 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, n
 
         //
         // Prepare the tools we want to use. When the model may call one, the conversation runs
-        // through the harness instead of being streamed straight away: tool rounds are not
-        // streamed, only the final answer is.
+        // through the harness instead of going straight to the streaming path below. It streams
+        // there as well, round by round -- what the harness adds is the tools in between.
         //
         var toolRegistry = Program.SERVICE_PROVIDER.GetService<ToolRegistry>();
         var toolExecutor = Program.SERVICE_PROVIDER.GetService<ToolExecutor>();
@@ -93,7 +93,7 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, n
         if (toolExecutor is not null && runnableTools.Count > 0)
         {
             var adapter = new AnthropicToolCallingAdapter(chatModel, [..messages], systemPrompt, maxTokens, apiParameters, runnableTools,
-                (requestDto, requestToken) => this.ExecuteMessagesRequest(requestDto, requestedSecret, requestToken));
+                (requestDto, requestToken) => this.StreamMessagesRequest(requestDto, requestedSecret, requestToken));
 
             var loop = Program.SERVICE_PROVIDER.GetRequiredService<IToolCallingLoop>();
             var loopContext = new ToolCallingLoopContext
@@ -151,30 +151,25 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, n
     }
 
     /// <summary>
-    /// Runs one non-streamed messages request, as the tool rounds need it.
+    /// Runs one round of a tool calling conversation against the messages API.
     /// </summary>
     /// <remarks>
-    /// Tool rounds are not streamed: the whole answer has to be there before its tool calls can
-    /// be executed. Only the final answer reaches the user through the streaming path.
+    /// Nothing but the HTTP request is done here. The retries, the timeouts, and the error
+    /// classification come from the shared stream reader, which the tool rounds used to go
+    /// without; reading the events is the adapter's business.
     /// </remarks>
-    /// <returns>The answer, or null when the request failed and the user was already told.</returns>
-    private async Task<AnthropicResponse?> ExecuteMessagesRequest(ChatRequest requestDto, RequestedSecret requestedSecret, CancellationToken token)
+    private IAsyncEnumerable<ServerSentEvent> StreamMessagesRequest(ChatRequest requestDto, RequestedSecret requestedSecret, CancellationToken token)
     {
-        using var request = new HttpRequestMessage(HttpMethod.Post, "messages");
-        request.Headers.Add("x-api-key", await requestedSecret.Secret.Decrypt(Program.ENCRYPTION));
-        request.Headers.Add("anthropic-version", "2023-06-01");
-        request.Content = new StringContent(JsonSerializer.Serialize(requestDto, JSON_SERIALIZER_OPTIONS), Encoding.UTF8, "application/json");
-
-        using var response = await this.HttpClient.SendAsync(request, token);
-        if (!response.IsSuccessStatusCode)
+        async Task<HttpRequestMessage> RequestBuilder()
         {
-            var responseBody = await response.Content.ReadAsStringAsync(token);
-            LOGGER.LogError("Tool calling messages request failed with status code {ResponseStatusCode} and body: '{ResponseBody}'.", response.StatusCode, responseBody);
-            await ToolCallingMessages.SendToolCallingRequestFailedAsync((int)response.StatusCode);
-            return null;
+            var request = new HttpRequestMessage(HttpMethod.Post, "messages");
+            request.Headers.Add("x-api-key", await requestedSecret.Secret.Decrypt(Program.ENCRYPTION));
+            request.Headers.Add("anthropic-version", "2023-06-01");
+            request.Content = new StringContent(JsonSerializer.Serialize(requestDto, JSON_SERIALIZER_OPTIONS), Encoding.UTF8, "application/json");
+            return request;
         }
 
-        return await response.Content.ReadFromJsonAsync<AnthropicResponse>(JSON_SERIALIZER_OPTIONS, token);
+        return this.ReadServerSentEventsAsync("Anthropic", "messages call", RequestBuilder, token);
     }
 
     #pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously