I let Codex test the AdditionalApiParameters and check for inconsistencies. It found some.

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

@@ -29,6 +29,9 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, "
         
         // Parse the API parameters:
         var apiParameters = this.ParseAdditionalApiParameters("system");
+        var maxTokens = 4_096;
+        if (TryPopIntParameter(apiParameters, "max_tokens", out var parsedMaxTokens))
+            maxTokens = parsedMaxTokens;
 
         // Build the list of messages:
         var messages = await chatThread.Blocks.BuildMessagesAsync(
@@ -73,7 +76,7 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, "
             Messages = [..messages],
             
             System = chatThread.PrepareSystemPrompt(settingsManager),
-            MaxTokens = apiParameters.TryGetValue("max_tokens", out var value) && value is int intValue ? intValue : 4_096,
+            MaxTokens = maxTokens,
             
             // Right now, we only support streaming completions:
             Stream = true,

app/MindWork AI Studio/Provider/BaseProvider.cs

@@ -731,7 +731,7 @@ public abstract class BaseProvider : IProvider, ISecretId
     /// <param name="keysToRemove">Optional list of keys to remove from the final dictionary
     /// (case-insensitive). The parameters stream, model, and messages are removed by default.</param>
     protected IDictionary<string, object> ParseAdditionalApiParameters(
-        params List<string> keysToRemove)
+        params string[] keysToRemove)
     {
         if(string.IsNullOrWhiteSpace(this.AdditionalJsonApiParameters))
             return new Dictionary<string, object>();
@@ -744,14 +744,23 @@ public abstract class BaseProvider : IProvider, ISecretId
             var dict = ConvertToDictionary(jsonDoc);
 
             // Some keys are always removed because we set them:
-            keysToRemove.Add("stream");
+            var removeSet = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
-            keysToRemove.Add("model");
+            if (keysToRemove.Length > 0)
-            keysToRemove.Add("messages");
+                removeSet.UnionWith(keysToRemove);
+            
+            removeSet.Add("stream");
+            removeSet.Add("model");
+            removeSet.Add("messages");
 
             // Remove the specified keys (case-insensitive):
-            var removeSet = new HashSet<string>(keysToRemove, StringComparer.OrdinalIgnoreCase);
+            if (removeSet.Count > 0)
-            foreach (var key in removeSet)
+            {
-                dict.Remove(key);
+                foreach (var key in dict.Keys.ToList())
+                {
+                    if (removeSet.Contains(key))
+                        dict.Remove(key);
+                }
+            }
 
             return dict;
         }
@@ -762,6 +771,85 @@ public abstract class BaseProvider : IProvider, ISecretId
         }
     }
     
+    protected static bool TryPopIntParameter(IDictionary<string, object> parameters, string key, out int value)
+    {
+        value = default;
+        if (!TryPopParameter(parameters, key, out var raw) || raw is null)
+            return false;
+        
+        switch (raw)
+        {
+            case int i:
+                value = i;
+                return true;
+            
+            case long l when l is >= int.MinValue and <= int.MaxValue:
+                value = (int)l;
+                return true;
+            
+            case double d when d is >= int.MinValue and <= int.MaxValue:
+                value = (int)d;
+                return true;
+            
+            case decimal m when m is >= int.MinValue and <= int.MaxValue:
+                value = (int)m;
+                return true;
+        }
+        
+        return false;
+    }
+    
+    protected static bool TryPopBoolParameter(IDictionary<string, object> parameters, string key, out bool value)
+    {
+        value = default;
+        if (!TryPopParameter(parameters, key, out var raw) || raw is null)
+            return false;
+        
+        switch (raw)
+        {
+            case bool b:
+                value = b;
+                return true;
+            
+            case string s when bool.TryParse(s, out var parsed):
+                value = parsed;
+                return true;
+            
+            case int i:
+                value = i != 0;
+                return true;
+            
+            case long l:
+                value = l != 0;
+                return true;
+            
+            case double d:
+                value = Math.Abs(d) > double.Epsilon;
+                return true;
+            
+            case decimal m:
+                value = m != 0;
+                return true;
+        }
+        
+        return false;
+    }
+    
+    private static bool TryPopParameter(IDictionary<string, object> parameters, string key, out object? value)
+    {
+        value = null;
+        if (parameters.Count == 0)
+            return false;
+        
+        var foundKey = parameters.Keys.FirstOrDefault(k => string.Equals(k, key, StringComparison.OrdinalIgnoreCase));
+        if (foundKey is null)
+            return false;
+        
+        value = parameters[foundKey];
+        parameters.Remove(foundKey);
+        return true;
+    }
+
     private static IDictionary<string, object> ConvertToDictionary(JsonElement element)
     {
         return element.EnumerateObject()

app/MindWork AI Studio/Provider/Mistral/ChatRequest.cs

@@ -14,7 +14,8 @@ public readonly record struct ChatRequest(
     string Model,
     IList<IMessageBase> Messages,
     bool Stream,
-    int RandomSeed,
+    [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    int? RandomSeed,
     bool SafePrompt = false
 )
 {

app/MindWork AI Studio/Provider/Mistral/ProviderMistral.cs

@@ -36,6 +36,8 @@ public sealed class ProviderMistral() : BaseProvider(LLMProviders.MISTRAL, "http
         
         // Parse the API parameters:
         var apiParameters = this.ParseAdditionalApiParameters();
+        var safePrompt = TryPopBoolParameter(apiParameters, "safe_prompt", out var parsedSafePrompt) && parsedSafePrompt;
+        var randomSeed = TryPopIntParameter(apiParameters, "random_seed", out var parsedRandomSeed) ? parsedRandomSeed : (int?)null;
 
         // Build the list of messages:
         var messages = await chatThread.Blocks.BuildMessagesUsingDirectImageUrlAsync(this.Provider, chatModel);
@@ -52,7 +54,8 @@ public sealed class ProviderMistral() : BaseProvider(LLMProviders.MISTRAL, "http
             
             // Right now, we only support streaming completions:
             Stream = true,
-            SafePrompt = apiParameters.TryGetValue("safe_prompt", out var value) && value is true,
+            RandomSeed = randomSeed,
+            SafePrompt = safePrompt,
             AdditionalApiParameters = apiParameters
         }, JSON_SERIALIZER_OPTIONS);