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

app/MindWork AI Studio/Provider/OpenAI/ResponsesToolCallingAdapter.cs

@@ -1,3 +1,5 @@
+using System.Runtime.CompilerServices;
+
 using AIStudio.Tools.ToolCallingSystem;
 using AIStudio.Tools.ToolCallingSystem.Harness;
 
@@ -13,7 +15,7 @@ namespace AIStudio.Provider.OpenAI;
 /// </remarks>
 public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> baseInput, IDictionary<string, object> apiParameters, IList<object> providerTools,
     IReadOnlyList<(ToolDefinition Definition, IToolImplementation Implementation)> runnableTools,
-    Func<ResponsesAPIRequest, CancellationToken, Task<ResponsesResponse?>> executeRequestAsync) : IToolCallingProviderAdapter
+    Func<ResponsesAPIRequest, CancellationToken, IAsyncEnumerable<ServerSentEvent>> streamRequestAsync) : IToolCallingProviderAdapter
 {
     private readonly List<object> internalItems = [];
     private readonly List<string> recordedRequestTexts = [];
@@ -32,7 +34,7 @@ public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> b
     private readonly IList<object> effectiveProviderTools = BuildEffectiveProviderTools(providerTools, runnableTools);
 
     /// <inheritdoc />
-    public async Task<ToolCallingRound?> ExecuteRoundAsync(string? finalResponseInstruction, bool includeTools, CancellationToken token = default)
+    public async IAsyncEnumerable<ToolCallingStreamEvent> ExecuteRoundAsync(string? finalResponseInstruction, bool includeTools, [EnumeratorCancellation] CancellationToken token = default)
     {
         var requestInput = new List<object>(baseInput);
         if (finalResponseInstruction is not null && requestInput.FirstOrDefault() is TextMessage systemPrompt)
@@ -45,21 +47,34 @@ public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> b
 
         requestInput.AddRange(this.internalItems);
 
-        var response = await executeRequestAsync(new ResponsesAPIRequest
+        var request = new ResponsesAPIRequest
         {
             Model = chatModel.Id,
             Input = requestInput,
-            Stream = false,
+            Stream = true,
             Store = false,
             Tools = includeTools ? this.effectiveProviderTools : [],
             AdditionalApiParameters = apiParameters,
-        }, token);
+        };
 
+        //
+        // The text goes out while it is being written, the round only once the stream closed it.
+        // Sources travel with the text because the API announces them as it cites them.
+        //
+        var accumulator = new ResponsesStreamAccumulator();
+        await foreach (var serverSentEvent in streamRequestAsync(request, token))
+        {
+            var part = accumulator.Process(serverSentEvent);
+            if (part.HasContent)
+                yield return ToolCallingStreamEvent.TextDelta(new ContentStreamChunk(part.TextDelta, part.Sources));
+        }
+
+        var response = accumulator.Build();
         if (response is null)
-            return null;
+            yield break;
 
         this.lastResponse = response;
-        return new ToolCallingRound(
+        yield return ToolCallingStreamEvent.RoundCompleted(new ToolCallingRound(
             response.GetTextOutput(),
             response.GetFunctionCalls()
                 .Select(call => new ToolCallingRequestedCall(
@@ -69,7 +84,7 @@ public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> b
                     !string.IsNullOrWhiteSpace(call.Name) && ToolExecutor.IsValidArgumentsJson(call.Arguments)))
                 .ToList(),
             
-            response.GetSources());
+            response.GetSources()));
     }
 
     /// <inheritdoc />