Works at the moment, but only for a hardcoded instance provider.

app/MindWork AI Studio/Provider/HuggingFace/ProviderHuggingFace.cs

@@ -0,0 +1,110 @@
+using System.Net.Http.Headers;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Text.Json;
+
+using AIStudio.Chat;
+using AIStudio.Provider.OpenAI;
+using AIStudio.Settings;
+
+namespace AIStudio.Provider.HuggingFace;
+
+public sealed class ProviderHuggingFace(ILogger logger) : BaseProvider("https://router.huggingface.co/cerebras/v1/", logger)
+{
+    #region Implementation of IProvider
+
+    /// <inheritdoc />
+    public override string Id => LLMProviders.HUGGINGFACE.ToName();
+
+    /// <inheritdoc />
+    public override string InstanceName { get; set; } = "HuggingFace";
+
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    {
+        // Get the API key:
+        var requestedSecret = await RUST_SERVICE.GetAPIKey(this);
+        if(!requestedSecret.Success)
+            yield break;
+
+        // Prepare the system prompt:
+        var systemPrompt = new Message
+        {
+            Role = "system",
+            Content = chatThread.PrepareSystemPrompt(settingsManager, chatThread, this.logger),
+        };
+        
+        // Prepare the HuggingFace HTTP chat request:
+        var huggingfaceChatRequest = JsonSerializer.Serialize(new ChatRequest
+        {
+            Model = chatModel.Id,
+            
+            // Build the messages:
+            // - First of all the system prompt
+            // - Then none-empty user and AI messages
+            Messages = [systemPrompt, ..chatThread.Blocks.Where(n => n.ContentType is ContentType.TEXT && !string.IsNullOrWhiteSpace((n.Content as ContentText)?.Text)).Select(n => new Message
+            {
+                Role = n.Role switch
+                {
+                    ChatRole.USER => "user",
+                    ChatRole.AI => "assistant",
+                    ChatRole.AGENT => "assistant",
+                    ChatRole.SYSTEM => "system",
+
+                    _ => "user",
+                },
+
+                Content = n.Content switch
+                {
+                    ContentText text => text.Text,
+                    _ => string.Empty,
+                }
+            }).ToList()],
+            Stream = true,
+        }, JSON_SERIALIZER_OPTIONS);
+
+        async Task<HttpRequestMessage> RequestBuilder()
+        {
+            // Build the HTTP post request:
+            var request = new HttpRequestMessage(HttpMethod.Post, "chat/completions");
+
+            // Set the authorization header:
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", await requestedSecret.Secret.Decrypt(ENCRYPTION));
+
+            // Set the content:
+            request.Content = new StringContent(huggingfaceChatRequest, Encoding.UTF8, "application/json");
+            return request;
+        }
+        
+        await foreach (var content in this.StreamChatCompletionInternal<ResponseStreamLine>("HuggingFace", RequestBuilder, token))
+            yield return content;
+    }
+
+    #pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<ImageURL> StreamImageCompletion(Model imageModel, string promptPositive, string promptNegative = FilterOperator.String.Empty, ImageURL referenceImageURL = default, [EnumeratorCancellation] CancellationToken token = default)
+    {
+        yield break;
+    }
+    #pragma warning restore CS1998 // Async method lacks 'await' operators and will run synchronously
+
+    /// <inheritdoc />
+    public override Task<IEnumerable<Model>> GetTextModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(Enumerable.Empty<Model>());
+    }
+
+    /// <inheritdoc />
+    public override Task<IEnumerable<Model>> GetImageModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(Enumerable.Empty<Model>());
+    }
+    
+    /// <inheritdoc />
+    public override Task<IEnumerable<Model>> GetEmbeddingModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(Enumerable.Empty<Model>());
+    }
+
+    #endregion
+}

app/MindWork AI Studio/Provider/LLMProviders.cs

@@ -17,6 +17,7 @@ public enum LLMProviders
     
     FIREWORKS = 5,
     GROQ = 6,
+    HUGGINGFACE = 13,
     
     SELF_HOSTED = 4,
     

app/MindWork AI Studio/Provider/LLMProvidersExtensions.cs

@@ -6,6 +6,7 @@ using AIStudio.Provider.Google;
 using AIStudio.Provider.Groq;
 using AIStudio.Provider.GWDG;
 using AIStudio.Provider.Helmholtz;
+using AIStudio.Provider.HuggingFace;
 using AIStudio.Provider.Mistral;
 using AIStudio.Provider.OpenAI;
 using AIStudio.Provider.SelfHosted;
@@ -37,6 +38,7 @@ public static class LLMProvidersExtensions
         
         LLMProviders.GROQ => "Groq",
         LLMProviders.FIREWORKS => "Fireworks.ai",
+        LLMProviders.HUGGINGFACE => "Hugging Face",
         
         LLMProviders.SELF_HOSTED => "Self-hosted",
         
@@ -58,6 +60,9 @@ public static class LLMProvidersExtensions
         
         LLMProviders.FIREWORKS => Confidence.USA_NOT_TRUSTED.WithRegion("America, U.S.").WithSources("https://fireworks.ai/terms-of-service").WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)),
         
+        // Not trusted, because huggingface only routes you to a third-party-provider and we can't make sure they do not use your data 
+        LLMProviders.HUGGINGFACE => Confidence.USA_NOT_TRUSTED.WithRegion("America, U.S.").WithSources("https://huggingface.co/terms-of-service").WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)), 
+        
         LLMProviders.OPEN_AI => Confidence.USA_NO_TRAINING.WithRegion("America, U.S.").WithSources(
             "https://platform.openai.com/docs/models/default-usage-policies-by-endpoint",
             "https://openai.com/policies/terms-of-use/",
@@ -112,6 +117,7 @@ public static class LLMProvidersExtensions
         LLMProviders.X => false,
         LLMProviders.GWDG => false,
         LLMProviders.DEEP_SEEK => false,
+        LLMProviders.HUGGINGFACE => false,
         
         //
         // Self-hosted providers are treated as a special case anyway.
@@ -159,6 +165,7 @@ public static class LLMProvidersExtensions
                 
                 LLMProviders.GROQ => new ProviderGroq(logger) { InstanceName = instanceName },
                 LLMProviders.FIREWORKS => new ProviderFireworks(logger) { InstanceName = instanceName },
+                LLMProviders.HUGGINGFACE => new ProviderHuggingFace(logger) { InstanceName = instanceName }, 
                 
                 LLMProviders.SELF_HOSTED => new ProviderSelfHosted(logger, host, hostname) { InstanceName = instanceName },
                 
@@ -187,6 +194,7 @@ public static class LLMProvidersExtensions
      
         LLMProviders.GROQ => "https://console.groq.com/",
         LLMProviders.FIREWORKS => "https://fireworks.ai/login",
+        LLMProviders.HUGGINGFACE => "https://huggingface.co/login",
         
         LLMProviders.HELMHOLTZ => "https://sdlaml.pages.jsc.fz-juelich.de/ai/guides/blablador_api_access/#step-1-register-on-gitlab",
         LLMProviders.GWDG => "https://docs.hpc.gwdg.de/services/saia/index.html#api-request",
@@ -205,6 +213,7 @@ public static class LLMProvidersExtensions
         LLMProviders.FIREWORKS => "https://fireworks.ai/account/billing",
         LLMProviders.DEEP_SEEK => "https://platform.deepseek.com/usage",
         LLMProviders.ALIBABA_CLOUD => "https://usercenter2-intl.aliyun.com/billing",
+        LLMProviders.HUGGINGFACE => "https://huggingface.co/settings/billing",
         
         _ => string.Empty,
     };
@@ -220,6 +229,7 @@ public static class LLMProvidersExtensions
         LLMProviders.GOOGLE => true,
         LLMProviders.DEEP_SEEK => true,
         LLMProviders.ALIBABA_CLOUD => true,
+        LLMProviders.HUGGINGFACE => true,
         
         _ => false,
     };
@@ -227,12 +237,14 @@ public static class LLMProvidersExtensions
     public static string GetModelsOverviewURL(this LLMProviders provider) => provider switch
     {
         LLMProviders.FIREWORKS => "https://fireworks.ai/models?show=Serverless",
+        LLMProviders.HUGGINGFACE => "https://huggingface.co/models?inference_provider=all",
         _ => string.Empty,
     };
 
     public static bool IsLLMModelProvidedManually(this LLMProviders provider) => provider switch
     {
         LLMProviders.FIREWORKS => true,
+        LLMProviders.HUGGINGFACE => true,
         _ => false,
     };
     
@@ -268,6 +280,7 @@ public static class LLMProvidersExtensions
         LLMProviders.FIREWORKS => true,
         LLMProviders.HELMHOLTZ => true,
         LLMProviders.GWDG => true,
+        LLMProviders.HUGGINGFACE => true,
         
         LLMProviders.SELF_HOSTED => host is Host.OLLAMA,
         
@@ -288,6 +301,7 @@ public static class LLMProvidersExtensions
         LLMProviders.FIREWORKS => true,
         LLMProviders.HELMHOLTZ => true,
         LLMProviders.GWDG => true,
+        LLMProviders.HUGGINGFACE => true,
         
         _ => false,
     };