Let the tool calling loop stream what each round produces

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

@@ -1,3 +1,5 @@
+using System.Runtime.CompilerServices;
+
 using AIStudio.Tools.ToolCallingSystem;
 using AIStudio.Tools.ToolCallingSystem.Harness;
 
@@ -27,7 +29,7 @@ public sealed class AnthropicToolCallingAdapter(Model chatModel, IList<IMessageB
     public IReadOnlyList<string> RecordedRequestTexts => this.recordedRequestTexts;
 
     /// <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)
     {
         //
         // The results of the previous round are flushed here rather than when they were recorded:
@@ -54,11 +56,20 @@ public sealed class AnthropicToolCallingAdapter(Model chatModel, IList<IMessageB
         }, token);
 
         if (response is null)
-            return null;
+            yield break;
 
         this.lastResponse = response;
-        return new ToolCallingRound(
-            response.GetTextOutput(),
+        
+        //
+        // The whole round arrives at once for now, so its text goes out as one delta. What the
+        // loop and the UI see is already the streaming shape; only the pieces are still large.
+        //
+        var textOutput = response.GetTextOutput();
+        if (!string.IsNullOrEmpty(textOutput))
+            yield return ToolCallingStreamEvent.TextDelta(textOutput);
+
+        yield return ToolCallingStreamEvent.RoundCompleted(new ToolCallingRound(
+            textOutput,
             response.GetToolUses()
                 .Select(toolUse => new ToolCallingRequestedCall(
                     toolUse.Id,
@@ -66,7 +77,7 @@ public sealed class AnthropicToolCallingAdapter(Model chatModel, IList<IMessageB
                     toolUse.Arguments,
                     ToolExecutor.IsValidArgumentsJson(toolUse.Arguments)))
                 .ToList(),
-            []);
+            []));
     }
 
     /// <inheritdoc />

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

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using System.Text.Json;
 
 using AIStudio.Tools.ToolCallingSystem;
@@ -30,7 +31,7 @@ public sealed class ChatCompletionToolCallingAdapter<TRequest>(
     public IReadOnlyList<string> RecordedRequestTexts => this.recordedRequestTexts;
 
     /// <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 requestSystemPrompt = finalResponseInstruction is null
             ? systemPrompt : systemPrompt with
@@ -54,7 +55,7 @@ public sealed class ChatCompletionToolCallingAdapter<TRequest>(
 
         var response = await executeRequestAsync(requestDto, token);
         if (response is null)
-            return null;
+            yield break;
 
         // The response comes from a provider, so its shape is a promise rather than a guarantee:
         // a JSON null for the choices field overwrites the initialized property with null.
@@ -74,12 +75,20 @@ public sealed class ChatCompletionToolCallingAdapter<TRequest>(
         var preparedCalls = this.PrepareToolCalls(responseChoice.Message.ToolCalls ?? []);
         this.lastToolCalls = preparedCalls.Select(x => x.ToolCall).ToList();
 
-        return new ToolCallingRound(
-            responseChoice.Message.Content ?? string.Empty,
+        //
+        // The whole round arrives at once for now, so its text goes out as one delta. What the
+        // loop and the UI see is already the streaming shape; only the pieces are still large.
+        //
+        var textOutput = responseChoice.Message.Content ?? string.Empty;
+        if (!string.IsNullOrEmpty(textOutput))
+            yield return ToolCallingStreamEvent.TextDelta(textOutput);
+
+        yield return ToolCallingStreamEvent.RoundCompleted(new ToolCallingRound(
+            textOutput,
             preparedCalls
                 .Select(x => new ToolCallingRequestedCall(x.ToolCall.Id!, x.ToolCall.Function!.Name!, x.ToolCall.Function!.Arguments!, x.IsValid))
                 .ToList(),
-            []);
+            []));
     }
 
     /// <inheritdoc />

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;
 
@@ -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)
@@ -56,11 +58,20 @@ public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> b
         }, token);
 
         if (response is null)
-            return null;
+            yield break;
 
         this.lastResponse = response;
-        return new ToolCallingRound(
-            response.GetTextOutput(),
+        
+        //
+        // The whole round arrives at once for now, so its text goes out as one delta. What the
+        // loop and the UI see is already the streaming shape; only the pieces are still large.
+        //
+        var textOutput = response.GetTextOutput();
+        if (!string.IsNullOrEmpty(textOutput))
+            yield return ToolCallingStreamEvent.TextDelta(textOutput);
+
+        yield return ToolCallingStreamEvent.RoundCompleted(new ToolCallingRound(
+            textOutput,
             response.GetFunctionCalls()
                 .Select(call => new ToolCallingRequestedCall(
                     call.CallId ?? string.Empty,
@@ -69,7 +80,7 @@ public sealed class ResponsesToolCallingAdapter(Model chatModel, IList<object> b
                     !string.IsNullOrWhiteSpace(call.Name) && ToolExecutor.IsValidArgumentsJson(call.Arguments)))
                 .ToList(),
             
-            response.GetSources());
+            response.GetSources()));
     }
 
     /// <inheritdoc />