Doppel-Klick Hard-Stop + ReadLineAsync Cancellation-Fix

Stop-Button: Zwei Stufen statt einer:
- 1. Klick: Graceful Stop (workCt) - laufende API-Calls/Tools abbrechen
- 2. Klick: Hard Stop (hardCt) - sofortiger Abbruch aus while-Loop

StreamingTracker: Zwei separate CancellationTokenSources (StopCts + HardCts),
Cancel() gibt 'graceful'/'hard'/null zurück je nach Stufe.

ReadLineAsync Cancellation-Fix: StreamReader.ReadLineAsync propagiert den
CancellationToken nicht zuverlässig an den underlying NetworkStream.
Bei extended thinking blockiert ReadLineAsync minutenlang ohne Reaktion
auf Cancellation. Fix: workCt.Register() disposed den HTTP-Stream,
damit ReadLineAsync sofort mit Exception abbricht.

Bug-Fix: OperationCanceledException in RunAgentChat/ChatNonStreaming wurde
vom generischen catch(Exception) geschluckt - Agent lief trotz Stop weiter.
Jetzt: catch(OperationCanceledException) { throw; } vor catch(Exception).

Frontend: Stop-Button zeigt Hard-Stop visuell (rot + Pulse-Animation),
SSE-Stream wird erst beim 2. Klick clientseitig abgebrochen.

Endpoints/ChatEndpoint.cs

@@ -175,14 +175,16 @@ public static class ChatEndpoint
         // Bei Choice-Response: toolChoice auf "auto" setzen, damit Claude frei antworten kann
         var effectiveToolChoice = isChoiceResponse ? "auto" : ctx.ToolChoice;
 
-        // Zwei separate CancellationTokens:
+        // Drei separate CancellationTokens:
-        // - workCt: Nur Stop-Button → für Anthropic API-Calls, Tool-Ausführungen, DB-Writes
+        // - workCt: Nur Stop-Button (graceful) → für Anthropic API-Calls, Tool-Ausführungen, DB-Writes
         //   Agent-Arbeit läuft bei Client-Disconnect weiter (Client pollt ja)
+        // - hardCt: Hard-Stop (Doppel-Klick) → sofortiger Abbruch aus while-Loop
         // - sseCt: Stop-Button + Client-Disconnect → für SSE-Writes an den Browser
         //   Bei Client-Disconnect werden SSE-Writes zu stillen No-Ops
-        var stopCts = streamingTracker.Start(sessionId, ctx.ChainId);
+        var tokens = streamingTracker.Start(sessionId, ctx.ChainId);
-        var workCt = stopCts.Token;
+        var workCt = tokens.StopToken;
-        using var sseLinkCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, stopCts.Token);
+        var hardCt = tokens.HardToken;
+        using var sseLinkCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, tokens.StopToken);
         var sseCt = sseLinkCts.Token;
 
         // SSE-Heartbeat: Alle 15s ein Kommentar senden, damit die Verbindung
@@ -204,7 +206,7 @@ public static class ChatEndpoint
 
         try
         {
-            await anthropic.StreamChat(res, ctx.ModelId, ctx.SystemPrompt, messages, ctx.ChainId, ctx.Workspace, sessionId, agentId: ctx.AgentId, useMemory: ctx.UseMemory, webSearchVersion: ctx.WebSearchVersion, maxIterations: ctx.MaxIterations, toolChoice: effectiveToolChoice, review: ctx.Review, finalizer: ctx.Finalizer, allowUserChoice: ctx.Agent?.AllowUserChoice ?? true, planMode: ctx.PlanMode, workCt: workCt, sseCt: sseCt);
+            await anthropic.StreamChat(res, ctx.ModelId, ctx.SystemPrompt, messages, ctx.ChainId, ctx.Workspace, sessionId, agentId: ctx.AgentId, useMemory: ctx.UseMemory, webSearchVersion: ctx.WebSearchVersion, maxIterations: ctx.MaxIterations, toolChoice: effectiveToolChoice, review: ctx.Review, finalizer: ctx.Finalizer, allowUserChoice: ctx.Agent?.AllowUserChoice ?? true, planMode: ctx.PlanMode, workCt: workCt, hardCt: hardCt, sseCt: sseCt);
         }
         finally
         {
@@ -225,7 +227,8 @@ public static class ChatEndpoint
             return;
         }
 
-        var cancelled = streamingTracker.Cancel(sessionId);
+        // Erster Klick = "graceful" (laufende Iteration fertig), zweiter = "hard" (sofort)
-        await res.WriteAsJsonAsync(new { stopped = cancelled });
+        var stopLevel = streamingTracker.Cancel(sessionId);
+        await res.WriteAsJsonAsync(new { stopped = stopLevel != null, level = stopLevel ?? "none" });
     }
 }

Services/AnthropicService.cs

@@ -52,6 +52,7 @@ public class AnthropicService
         bool allowUserChoice = true,
         bool planMode = false,
         CancellationToken workCt = default,
+        CancellationToken hardCt = default,
         CancellationToken sseCt = default)
     {
         var sw = System.Diagnostics.Stopwatch.StartNew();
@@ -71,6 +72,8 @@ public class AnthropicService
         {
             while (iterations < maxIterations)
             {
+                // Hard-Stop: Sofortiger Abbruch aus while-Loop (Doppel-Klick Stop)
+                hardCt.ThrowIfCancellationRequested();
                 workCt.ThrowIfCancellationRequested();
                 iterations++;
 
@@ -260,6 +263,9 @@ public class AnthropicService
                 }
 
                 messages.Add(new { role = "user", content = toolResults });
+
+                // Hard-Stop Check nach Tool-Ausführung: Sofort raus statt nächste Iteration
+                hardCt.ThrowIfCancellationRequested();
             }
 
             await FinalizeChain(chain, usage, iterations, "max_iterations", sw);
@@ -268,7 +274,14 @@ public class AnthropicService
         }
         catch (OperationCanceledException)
         {
-            // Stop-Button gedrückt (workCt wurde gecancelled)
+            // Stop-Button gedrückt (workCt oder hardCt wurde gecancelled)
+            await FinalizeChain(chain, usage, iterations, "stopped", sw);
+        }
+        catch (Exception) when (workCt.IsCancellationRequested || hardCt.IsCancellationRequested)
+        {
+            // Stream-Dispose durch CancellationToken-Registration löst
+            // ObjectDisposedException/IOException aus statt OperationCanceledException.
+            // Wenn workCt/hardCt gecancelled ist, ist das ein regulärer Stop.
             await FinalizeChain(chain, usage, iterations, "stopped", sw);
         }
         catch (Exception ex)
@@ -752,6 +765,7 @@ public class AnthropicService
                     string toolResult;
                     bool isError = false;
                     try { toolResult = await _toolService.ExecuteTool(toolName, toolInput, agentWorkspace, _memoryService, agentId, workCt); }
+                    catch (OperationCanceledException) { throw; }
                     catch (Exception ex) { toolResult = $"Fehler: {ex.Message}"; isError = true; }
 
                     toolResults.Add(new
@@ -946,6 +960,7 @@ public class AnthropicService
                         string toolResult;
                         bool isError = false;
                         try { toolResult = await _toolService.ExecuteTool(toolName, toolInput, ctx.Workspace, _memoryService, ctx.AgentId); }
+                        catch (OperationCanceledException) { throw; }
                         catch (Exception ex) { toolResult = $"Fehler: {ex.Message}"; isError = true; }
 
                         toolResults.Add(new
@@ -1067,6 +1082,11 @@ public class AnthropicService
         CancellationToken sseCt = default)
     {
         var stream = await httpResp.Content.ReadAsStreamAsync(workCt);
+        // Bei Cancellation den Stream disposen, damit ReadLineAsync sofort abbricht.
+        // StreamReader.ReadLineAsync propagiert den CancellationToken nicht zuverlässig
+        // an den underlying NetworkStream – der Read blockiert sonst bis Anthropic
+        // das nächste Chunk sendet (kann bei extended thinking Minuten dauern).
+        using var ctReg = workCt.Register(() => { try { stream.Dispose(); } catch { } });
         using var reader = new StreamReader(stream);
 
         var stopReason = "";

Services/StreamingTracker.cs

@@ -7,37 +7,56 @@ public class StreamingTracker
 {
     private readonly ConcurrentDictionary<string, StreamingState> _streaming = new ConcurrentDictionary<string, StreamingState>();
 
-    public CancellationTokenSource Start(string sessionId, string chainId)
+    public StreamingTokens Start(string sessionId, string chainId)
     {
-        var cts = new CancellationTokenSource();
+        var stopCts = new CancellationTokenSource();
-        _streaming[sessionId] = new StreamingState(chainId, cts);
+        var hardCts = new CancellationTokenSource();
-        return cts;
+        var state = new StreamingState(chainId, stopCts, hardCts);
+        _streaming[sessionId] = state;
+        return new StreamingTokens(stopCts.Token, hardCts.Token);
     }
 
     public void Stop(string sessionId)
     {
         if (_streaming.TryRemove(sessionId, out var state))
         {
-            state.Cts.Dispose();
+            state.StopCts.Dispose();
+            state.HardCts.Dispose();
         }
     }
 
     /// <summary>
-    /// Cancels the running stream for a session. Returns true if a stream was cancelled.
+    /// Cancels the running stream for a session.
+    /// First call = graceful (laufende Iteration wird fertig).
+    /// Second call = hard (sofortiger Abbruch aus while-Loop).
+    /// Returns "graceful", "hard" or null if not streaming.
     /// </summary>
-    public bool Cancel(string sessionId)
+    public string Cancel(string sessionId)
     {
         if (_streaming.TryGetValue(sessionId, out var state))
         {
-            try { state.Cts.Cancel(); } catch { }
+            if (!state.StopCts.IsCancellationRequested)
-            return true;
+            {
+                // Erster Klick → graceful stop
+                try { state.StopCts.Cancel(); } catch { }
+                return "graceful";
+            }
+            else if (!state.HardCts.IsCancellationRequested)
+            {
+                // Zweiter Klick → hard stop
+                try { state.HardCts.Cancel(); } catch { }
+                return "hard";
+            }
+            return "hard"; // Bereits beides gecancelled
         }
-        return false;
+        return null;
     }
 
     public bool IsStreaming(string sessionId) => _streaming.ContainsKey(sessionId);
 
     public string GetChainId(string sessionId) => _streaming.TryGetValue(sessionId, out var state) ? state.ChainId : null;
 
-    private record StreamingState(string ChainId, CancellationTokenSource Cts);
+    public record StreamingTokens(CancellationToken StopToken, CancellationToken HardToken);
+
+    private record StreamingState(string ChainId, CancellationTokenSource StopCts, CancellationTokenSource HardCts);
 }

wwwroot/css/chat.css

@@ -440,6 +440,18 @@
   background: rgb(from var(--dangerous) r g b / 0.15);
 }
 
+.stop-btn.stop-hard {
+  background: var(--dangerous);
+  color: var(--primary-text);
+  animation: pulse-hard 0.6s ease-in-out;
+}
+
+@keyframes pulse-hard {
+  0% { transform: scale(1); }
+  50% { transform: scale(1.15); }
+  100% { transform: scale(1); }
+}
+
 .input-area textarea {
   flex: 1;
   min-height: 0;

wwwroot/js/chat.js

@@ -170,11 +170,23 @@ async function clearChat() {
   showArchiveLoadButton();
 }
 
+let _stopClickCount = 0;
+
 function stopStreaming() {
-  if (_abortController) {
+  _stopClickCount++;
-    _abortController.abort();
+
+  if (_stopClickCount >= 2) {
+    // Hard-Stop: Sofortiger Abbruch (Doppel-Klick)
+    var btn = $('#stop');
+    if (btn) {
+      btn.classList.add('stop-hard');
+      btn.title = 'Hard-Stop gesendet!';
+    }
+    // SSE-Stream clientseitig sofort abbrechen
+    if (_abortController) _abortController.abort();
   }
-  // Backend explizit stoppen (kills laufende Tools/API-Calls)
+
+  // Backend explizit stoppen (graceful beim 1. Klick, hard beim 2.)
   var sid = getCurrentSessionId();
   if (sid) apiStopChat(sid).catch(function() {});
 }
@@ -193,6 +205,7 @@ async function _runStream(fetchPromise) {
   _abortController = new AbortController();
   _currentToolBox = null;
   _chatAbandoned = false;
+  _stopClickCount = 0;
   setMetaHtml('<span><i class="fa fa-hourglass-half"></i> Streaming...</span>');
 
   try {
@@ -244,6 +257,8 @@ async function _runStream(fetchPromise) {
       sendBtn.disabled = false;
       sendBtn.hidden = false;
       stopBtn.hidden = true;
+      stopBtn.classList.remove('stop-hard');
+      stopBtn.title = 'Antwort abbrechen';
       isStreaming = false;
       _abortController = null;
     }