diff --git a/Services/AnthropicService.cs b/Services/AnthropicService.cs
index 3eb23ec..f2f8308 100644
--- a/Services/AnthropicService.cs
+++ b/Services/AnthropicService.cs
@@ -161,16 +161,13 @@ public class AnthropicService
                     }
                     else if (blockType == "web_search_tool_result")
                     {
-                        var sources = ExtractWebSearchSources(el);
-                        if (sources.Count > 0)
+                        // Raw-JSON speichern für History-Rebuild (API braucht den vollständigen Block)
+                        await _db.SaveMessage(new MessageRecord
                         {
-                            await _db.SaveMessage(new MessageRecord
-                            {
-                                ChainId = chainId, Iteration = iterations,
-                                Role = "assistant", Type = "web_search_result",
-                                Content = JsonSerializer.Serialize(sources)
-                            });
-                        }
+                            ChainId = chainId, Iteration = iterations,
+                            Role = "assistant", Type = "web_search_result",
+                            Content = el.GetRawText()
+                        });
                     }
                     else if (blockType.EndsWith("_tool_result"))
                     {
@@ -838,19 +835,16 @@ public class AnthropicService
                 else if (blockType == "web_search_tool_result")
                 {
                     assistantContent.Add(JsonSerializer.Deserialize<JsonElement>(block.GetRawText()));
-                    var sources = ExtractWebSearchSources(block);
-                    if (sources.Count > 0)
+                    // Raw-JSON speichern für History-Rebuild (API braucht den vollständigen Block)
+                    await _db.SaveMessage(new MessageRecord
                     {
-                        await _db.SaveMessage(new MessageRecord
-                        {
-                            ChainId = chainId,
-                            Iteration = baseIterations + iterations,
-                            Role = "assistant",
-                            Type = "web_search_result",
-                            Content = JsonSerializer.Serialize(sources),
-                            Tag = agentType
-                        });
-                    }
+                        ChainId = chainId,
+                        Iteration = baseIterations + iterations,
+                        Role = "assistant",
+                        Type = "web_search_result",
+                        Content = block.GetRawText(),
+                        Tag = agentType
+                    });
                 }
                 else if (blockType == "server_tool_use")
                 {
@@ -1019,16 +1013,13 @@ public class AnthropicService
                     else if (blockType == "web_search_tool_result")
                     {
                         assistantContent.Add(JsonSerializer.Deserialize<JsonElement>(block.GetRawText()));
-                        var sources = ExtractWebSearchSources(block);
-                        if (sources.Count > 0)
+                        // Raw-JSON speichern für History-Rebuild (API braucht den vollständigen Block)
+                        await _db.SaveMessage(new MessageRecord
                         {
-                            await _db.SaveMessage(new MessageRecord
-                            {
-                                ChainId = ctx.ChainId, Iteration = iterations,
-                                Role = "assistant", Type = "web_search_result",
-                                Content = JsonSerializer.Serialize(sources)
-                            });
-                        }
+                            ChainId = ctx.ChainId, Iteration = iterations,
+                            Role = "assistant", Type = "web_search_result",
+                            Content = block.GetRawText()
+                        });
                     }
                     else if (blockType == "server_tool_use")
                     {
diff --git a/Services/ChatService.cs b/Services/ChatService.cs
index e741ed3..4a994df 100644
--- a/Services/ChatService.cs
+++ b/Services/ChatService.cs
@@ -419,6 +419,34 @@ Für welche Plattform soll die App entwickelt werden? Web, Mobile oder Desktop?
                             });
                         }
                     }
+                    else if (msg.Role == "assistant" && msg.Type == "web_search_result")
+                    {
+                        // web_search_tool_result – Raw-JSON in den Assistant-Content-Block einfügen
+                        // (API erwartet web_search_tool_result nach server_tool_use vom Typ web_search)
+                        JsonElement resultEl;
+                        try { resultEl = JsonSerializer.Deserialize<JsonElement>(msg.Content ?? "{}"); }
+                        catch { continue; }
+
+                        // Rückwärtskompatibilität: Alte Einträge enthalten nur Sources-Array statt Raw-JSON
+                        // Diese überspringen, da sie kein gültiger web_search_tool_result-Block sind
+                        if (resultEl.ValueKind == JsonValueKind.Array) continue;
+
+                        var lastAssistant = history.Count > 0 ? history[history.Count - 1] : null;
+                        if (lastAssistant is Dictionary<string, object> dict &&
+                            dict.TryGetValue("role", out var role) && role.ToString() == "assistant" &&
+                            dict.TryGetValue("content", out var existingContent) && existingContent is List<object> contentList)
+                        {
+                            contentList.Add(resultEl);
+                        }
+                        else
+                        {
+                            history.Add(new Dictionary<string, object>
+                            {
+                                ["role"] = "assistant",
+                                ["content"] = new List<object> { resultEl }
+                            });
+                        }
+                    }
                     else if (msg.Role == "user" && msg.Type == "tool_result")
                     {
                         var lastUser = history.Count > 0 ? history[history.Count - 1] : null;
@@ -562,9 +590,76 @@ Für welche Plattform soll die App entwickelt werden? Web, Mobile oder Desktop?
             }
         }
 
+        // Post-Processing: Orphaned web_search server_tool_use entfernen
+        // Bei alten DB-Einträgen wurde web_search_tool_result nur als Sources-Array gespeichert,
+        // nicht als Raw-JSON → BuildHistoryFromDb überspringt sie (Array-Check) →
+        // server_tool_use mit name "web_search" hat kein zugehöriges web_search_tool_result →
+        // API 400 Fehler. Lösung: Solche orphaned Blöcke aus der History entfernen.
+        CleanOrphanedWebSearchBlocks(history);
+
         return history;
     }
 
+    /// <summary>
+    /// Entfernt server_tool_use-Blöcke vom Typ "web_search" aus assistant-Messages,
+    /// wenn kein zugehöriger web_search_tool_result-Block in derselben Message existiert.
+    /// </summary>
+    private static void CleanOrphanedWebSearchBlocks(List<object> history)
+    {
+        foreach (var msg in history)
+        {
+            if (msg is not Dictionary<string, object> dict) continue;
+            if (!dict.TryGetValue("role", out var role) || role.ToString() != "assistant") continue;
+            if (!dict.TryGetValue("content", out var content) || content is not List<object> contentList) continue;
+
+            // Prüfe ob es web_search server_tool_use gibt
+            var webSearchToolUseIds = new HashSet<string>();
+            var webSearchToolResultIds = new HashSet<string>();
+
+            foreach (var block in contentList)
+            {
+                var json = JsonSerializer.Serialize(block);
+                JsonElement el;
+                try { el = JsonSerializer.Deserialize<JsonElement>(json); }
+                catch { continue; }
+
+                var type = el.TryGetProperty("type", out var t) ? t.GetString() : "";
+                if (type == "server_tool_use")
+                {
+                    var name = el.TryGetProperty("name", out var n) ? n.GetString() : "";
+                    var id = el.TryGetProperty("id", out var idProp) ? idProp.GetString() : "";
+                    if (name == "web_search" && !string.IsNullOrEmpty(id))
+                        webSearchToolUseIds.Add(id);
+                }
+                else if (type == "web_search_tool_result")
+                {
+                    var toolUseId = el.TryGetProperty("tool_use_id", out var tid) ? tid.GetString() : "";
+                    if (!string.IsNullOrEmpty(toolUseId))
+                        webSearchToolResultIds.Add(toolUseId);
+                }
+            }
+
+            // Orphaned = server_tool_use IDs ohne zugehörige web_search_tool_result
+            var orphanedIds = webSearchToolUseIds.Except(webSearchToolResultIds).ToHashSet();
+            if (orphanedIds.Count == 0) continue;
+
+            // Entferne orphaned server_tool_use Blöcke
+            contentList.RemoveAll(block =>
+            {
+                var json = JsonSerializer.Serialize(block);
+                JsonElement el;
+                try { el = JsonSerializer.Deserialize<JsonElement>(json); }
+                catch { return false; }
+
+                var type = el.TryGetProperty("type", out var t) ? t.GetString() : "";
+                if (type != "server_tool_use") return false;
+
+                var id = el.TryGetProperty("id", out var idProp) ? idProp.GetString() : "";
+                return orphanedIds.Contains(id);
+            });
+        }
+    }
+
     /// <summary>
     /// Baut einen SubAgentContext für Preparer/Review/Finalizer.
     /// Gemeinsame Logik: Agent laden, Model auflösen, SystemPrompt bauen, ToolChoice bestimmen.
diff --git a/wwwroot/js/history.js b/wwwroot/js/history.js
index 327f470..c7dbf55 100644
--- a/wwwroot/js/history.js
+++ b/wwwroot/js/history.js
@@ -1,3 +1,26 @@
+// ── Web Search Sources Extraction ──
+// Unterstützt zwei Formate:
+// - Alt: JSON-Array von {url, title} (nur Sources)
+// - Neu: Raw web_search_tool_result JSON (content[].type === 'web_search_result')
+function _extractWebSearchSources(content) {
+  try {
+    var parsed = JSON.parse(content || '[]');
+    // Altes Format: direktes Array von Sources
+    if (Array.isArray(parsed)) return parsed;
+    // Neues Format: Raw web_search_tool_result mit content-Array
+    if (parsed.content && Array.isArray(parsed.content)) {
+      var sources = [];
+      parsed.content.forEach(function(item) {
+        if (item.type === 'web_search_result' && item.url) {
+          sources.push({ url: item.url, title: item.title || '' });
+        }
+      });
+      return sources;
+    }
+    return [];
+  } catch(e) { return []; }
+}
+
 // ── Image Attachments Auto-Loading ──
 
 async function _autoLoadImageAttachments(messageId) {
@@ -246,8 +269,7 @@ function _renderMessagesIntoFragment(fragment, msgs, imageMessageIds, opts) {
         break;
       case 'web_search_result': {
         if (!isToolVisible('web_search')) continue;
-        var wsSources = [];
-        try { wsSources = JSON.parse(msg.content || '[]'); } catch(e) {}
+        var wsSources = _extractWebSearchSources(msg.content);
         if (wsSources.length === 0) continue;
         var wsDiv = document.createElement('div');
         wsDiv.className = 'tool-box' + (archived ? ' archived' : '');
@@ -350,8 +372,7 @@ function _renderReviewGroup(tagGroup, archived) {
     } else if (m.type === 'web_search_result') {
       if (!isToolVisible('web_search')) continue;
       flushText();
-      var wsSources = [];
-      try { wsSources = JSON.parse(m.content || '[]'); } catch(e) {}
+      var wsSources = _extractWebSearchSources(m.content);
       if (wsSources.length > 0) {
         var wsDiv = document.createElement('div');
         wsDiv.className = 'tool-box review-tool-box' + (archived ? ' archived' : '');
diff --git a/wwwroot/js/pages/shared-page.js b/wwwroot/js/pages/shared-page.js
index 1f3f7ce..00f4927 100644
--- a/wwwroot/js/pages/shared-page.js
+++ b/wwwroot/js/pages/shared-page.js
@@ -29,8 +29,7 @@ registerPage('shared', {
 
         // Web-Search-Results als Tool-Box mit Sources rendern
         if (msg.type === 'web_search_result') {
-          var wsSources = [];
-          try { wsSources = JSON.parse(c || '[]'); } catch(e) {}
+          var wsSources = _extractWebSearchSources(c);
           if (wsSources.length === 0) continue;
           const div = document.createElement('div');
           div.className = 'tool-box';