fix: Windows-Kompatibilität - Streaming, Execute-Deadlock, Plan-Modus bei Choice

- HttpResponseMessage mit using disposen (3 Stellen in AnthropicService)
  verhindert Socket-Exhaustion unter Windows (2 Connections/Host Limit)
- SSE DisableBuffering() in ChatEndpoint für sofortigen Flush unter Windows
- Execute: stdout/stderr vor WaitForExitAsync lesen statt danach
  verhindert Pipe-Deadlock bei vollem Buffer (Windows: 4KB)
- Plan-Modus: Frontend sendet planMode bei Choice-Response mit
  Backend-Fallback auf vorherigen Chain entfernt - User-Entscheidung gilt

Endpoints/ChatEndpoint.cs

@@ -52,19 +52,7 @@ public static class ChatEndpoint
         var userId = req.HttpContext.GetUserId();
         var maxIterations = config.GetValue<int>("MaxIterations", 100);
 
-        // Bei Choice-Response: planMode vom vorherigen Chain übernehmen
+        var ctx = await chatService.PrepareContext(sessionId, userId, maxIterations, planMode: body.PlanMode);
-        var effectivePlanMode = body.PlanMode;
-        if (isChoiceResponse && !effectivePlanMode)
-        {
-            var prevChainId = await chatService.FindChainWithToolCall(sessionId, body.ChoiceToolCallId);
-            if (prevChainId != null)
-            {
-                var prevChain = await db.GetChain(prevChainId);
-                if (prevChain != null) effectivePlanMode = prevChain.PlanMode;
-            }
-        }
-
-        var ctx = await chatService.PrepareContext(sessionId, userId, maxIterations, planMode: effectivePlanMode);
         if (ctx == null)
         {
             res.StatusCode = 400;
@@ -132,6 +120,10 @@ public static class ChatEndpoint
         res.Headers["Cache-Control"] = "no-cache";
         res.Headers["Connection"] = "keep-alive";
 
+        // Response-Buffering deaktivieren – wichtig für SSE unter Windows
+        var bufferingFeature = res.HttpContext.Features.Get<Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature>();
+        bufferingFeature?.DisableBuffering();
+
         // ── Preparer-Agent Phase (vor dem Worker) ──
         if (ctx.Preparer != null && !isChoiceResponse)
         {

Services/AnthropicService.cs

@@ -92,7 +92,7 @@ public class AnthropicService
                 LogPayload(json, sessionId, chainId, iterations);
                 var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
 
-                var httpResp = await client.SendAsync(
+                using var httpResp = await client.SendAsync(
                     new HttpRequestMessage(HttpMethod.Post, "https://api.anthropic.com/v1/messages") { Content = httpContent },
                     HttpCompletionOption.ResponseHeadersRead,
                     cancellationToken
@@ -665,7 +665,7 @@ public class AnthropicService
             LogPayload(json, sessionId, chainId, baseIterations + iterations);
             var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
 
-            var httpResp = await client.SendAsync(
+            using var httpResp = await client.SendAsync(
                 new HttpRequestMessage(HttpMethod.Post, "https://api.anthropic.com/v1/messages") { Content = httpContent },
                 cancellationToken: cancellationToken);
 
@@ -873,7 +873,7 @@ public class AnthropicService
                 LogPayload(json, ctx.SessionId, ctx.ChainId, iterations);
                 var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
 
-                var httpResp = await client.SendAsync(
+                using var httpResp = await client.SendAsync(
                     new HttpRequestMessage(HttpMethod.Post, "https://api.anthropic.com/v1/messages") { Content = httpContent });
 
                 var respBody = await httpResp.Content.ReadAsStringAsync();

Services/ToolService.cs

@@ -388,6 +388,10 @@ public class ToolService
                 // Timeout (180s) UND externen CancellationToken verknüpfen
                 using var cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
                 cts.CancelAfter(TimeSpan.FromSeconds(180));
+                // stdout/stderr VOR WaitForExit lesen – verhindert Deadlock
+                // wenn Pipe-Buffer volllaufen (Windows: nur 4KB!)
+                var stdoutTask = proc.StandardOutput.ReadToEndAsync();
+                var stderrTask = proc.StandardError.ReadToEndAsync();
                 try
                 {
                     await proc.WaitForExitAsync(cts.Token);
@@ -399,8 +403,8 @@ public class ToolService
                     cancellationToken.ThrowIfCancellationRequested();
                     return "Fehler: Timeout nach 180 Sekunden - Prozess abgebrochen";
                 }
-                var stdout = await proc.StandardOutput.ReadToEndAsync();
+                var stdout = await stdoutTask;
-                var stderr = await proc.StandardError.ReadToEndAsync();
+                var stderr = await stderrTask;
                 var result = new StringBuilder();
                 if (!string.IsNullOrEmpty(stdout)) result.Append(stdout);
                 if (!string.IsNullOrEmpty(stderr))

wwwroot/js/api.js

@@ -52,11 +52,13 @@ async function apiChat(content, sessionId, signal, planMode) {
   });
 }
 
-async function apiChatChoice(sessionId, choiceToolCallId, choiceResult, signal) {
+async function apiChatChoice(sessionId, choiceToolCallId, choiceResult, signal, planMode) {
+  var payload = { sessionId, choiceToolCallId, choiceResult };
+  if (planMode) payload.planMode = true;
   return fetch('/api/chat', {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ sessionId, choiceToolCallId, choiceResult }),
+    body: JSON.stringify(payload),
     signal
   });
 }

wwwroot/js/chat.js

@@ -343,5 +343,5 @@ async function handleChoiceClick(toolCallId, choice, bubbleDiv) {
   });
   bubbleDiv.classList.add('choice-answered');
 
-  await _runStream((signal) => apiChatChoice(getCurrentSessionId(), toolCallId, choice, signal));
+  await _runStream((signal) => apiChatChoice(getCurrentSessionId(), toolCallId, choice, signal, _planModeActive));
 }