Added support for Perplexity (#545)

Co-authored-by: Thorsten Sommer <mail@tsommer.org>

app/MindWork AI Studio/Provider/AlibabaCloud/ProviderAlibabaCloud.cs

@@ -21,7 +21,7 @@ public sealed class ProviderAlibabaCloud(ILogger logger) : BaseProvider("https:/
     public override string InstanceName { get; set; } = "AlibabaCloud";
     
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

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

@@ -18,7 +18,7 @@ public sealed class ProviderAnthropic(ILogger logger) : BaseProvider("https://ap
     public override string InstanceName { get; set; } = "Anthropic";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

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

@@ -13,7 +13,7 @@ public readonly record struct ResponseStreamLine(string Type, int Index, Delta D
     public bool ContainsContent() => this != default && !string.IsNullOrWhiteSpace(this.Delta.Text);
 
     /// <inheritdoc />
-    public string GetContent() => this.Delta.Text;
+    public ContentStreamChunk GetContent() => new(this.Delta.Text, []);
 }
 
 /// <summary>

app/MindWork AI Studio/Provider/BaseProvider.cs

@@ -63,7 +63,7 @@ public abstract class BaseProvider : IProvider, ISecretId
     public abstract string InstanceName { get; set; }
     
     /// <inheritdoc />
-    public abstract IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, CancellationToken token = default);
+    public abstract IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, CancellationToken token = default);
     
     /// <inheritdoc />
     public abstract IAsyncEnumerable<ImageURL> StreamImageCompletion(Model imageModel, string promptPositive, string promptNegative = FilterOperator.String.Empty, ImageURL referenceImageURL = default, CancellationToken token = default);
@@ -96,7 +96,7 @@ public abstract class BaseProvider : IProvider, ISecretId
     /// <param name="requestBuilder">A function that builds the request.</param>
     /// <param name="token">The cancellation token.</param>
     /// <returns>The status object of the request.</returns>
-    protected async Task<HttpRateLimitedStreamResult> SendRequest(Func<Task<HttpRequestMessage>> requestBuilder, CancellationToken token = default)
+    private async Task<HttpRateLimitedStreamResult> SendRequest(Func<Task<HttpRequestMessage>> requestBuilder, CancellationToken token = default)
     {
         const int MAX_RETRIES = 6;
         const double RETRY_DELAY_SECONDS = 4;
@@ -189,7 +189,7 @@ public abstract class BaseProvider : IProvider, ISecretId
         return new HttpRateLimitedStreamResult(true, false, string.Empty, response);
     }
 
-    protected async IAsyncEnumerable<string> StreamChatCompletionInternal<T>(string providerName, Func<Task<HttpRequestMessage>> requestBuilder, [EnumeratorCancellation] CancellationToken token = default) where T : struct, IResponseStreamLine
+    protected async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletionInternal<T>(string providerName, Func<Task<HttpRequestMessage>> requestBuilder, [EnumeratorCancellation] CancellationToken token = default) where T : struct, IResponseStreamLine
     {
         StreamReader? streamReader = null;
         try

app/MindWork AI Studio/Provider/ContentStreamChunk.cs

@@ -0,0 +1,16 @@
+namespace AIStudio.Provider;
+
+/// <summary>
+/// A chunk of content from a content stream, along with its associated sources.
+/// </summary>
+/// <param name="Content">The text content of the chunk.</param>
+/// <param name="Sources">The list of sources associated with the chunk.</param>
+public sealed record ContentStreamChunk(string Content, IList<ISource> Sources)
+{
+    /// <summary>
+    /// Implicit conversion to string.
+    /// </summary>
+    /// <param name="chunk">The content stream chunk.</param>
+    /// <returns>The text content of the chunk.</returns>
+    public static implicit operator string(ContentStreamChunk chunk) => chunk.Content;
+}

app/MindWork AI Studio/Provider/DeepSeek/ProviderDeepSeek.cs

@@ -20,7 +20,7 @@ public sealed class ProviderDeepSeek(ILogger logger) : BaseProvider("https://api
     public override string InstanceName { get; set; } = "DeepSeek";
     
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/Fireworks/ProviderFireworks.cs

@@ -19,7 +19,7 @@ public class ProviderFireworks(ILogger logger) : BaseProvider("https://api.firew
     public override string InstanceName { get; set; } = "Fireworks.ai";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/Fireworks/ResponseStreamLine.cs

@@ -14,7 +14,7 @@ public readonly record struct ResponseStreamLine(string Id, string Object, uint
     public bool ContainsContent() => this != default && this.Choices.Count > 0;
 
     /// <inheritdoc />
-    public string GetContent() => this.Choices[0].Delta.Content;
+    public ContentStreamChunk GetContent() => new(this.Choices[0].Delta.Content, []);
 }
 
 /// <summary>

app/MindWork AI Studio/Provider/GWDG/ProviderGWDG.cs

@@ -20,7 +20,7 @@ public sealed class ProviderGWDG(ILogger logger) : BaseProvider("https://chat-ai
     public override string InstanceName { get; set; } = "GWDG SAIA";
     
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/Google/ProviderGoogle.cs

@@ -20,7 +20,7 @@ public class ProviderGoogle(ILogger logger) : BaseProvider("https://generativela
     public override string InstanceName { get; set; } = "Google Gemini";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/Groq/ProviderGroq.cs

@@ -20,7 +20,7 @@ public class ProviderGroq(ILogger logger) : BaseProvider("https://api.groq.com/o
     public override string InstanceName { get; set; } = "Groq";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/Helmholtz/ProviderHelmholtz.cs

@@ -20,7 +20,7 @@ public sealed class ProviderHelmholtz(ILogger logger) : BaseProvider("https://ap
     public override string InstanceName { get; set; } = "Helmholtz Blablador";
     
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

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

@@ -25,7 +25,7 @@ public sealed class ProviderHuggingFace : BaseProvider
     public override string InstanceName { get; set; } = "HuggingFace";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/IProvider.cs

@@ -27,7 +27,7 @@ public interface IProvider
     /// <param name="settingsManager">The settings manager instance to use.</param>
     /// <param name="token">The cancellation token.</param>
     /// <returns>The chat completion stream.</returns>
-    public IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, CancellationToken token = default);
+    public IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, CancellationToken token = default);
     
     /// <summary>
     /// Starts an image completion stream.

app/MindWork AI Studio/Provider/IResponseStreamLine.cs

@@ -12,5 +12,17 @@ public interface IResponseStreamLine
     /// Gets the content of the response line.
     /// </summary>
     /// <returns>The content of the response line.</returns>
-    public string GetContent();
+    public ContentStreamChunk GetContent();
+    
+    /// <summary>
+    /// Checks if the response line contains any sources.
+    /// </summary>
+    /// <returns>True when the response line contains sources, false otherwise.</returns>
+    public bool ContainsSources() => false;
+    
+    /// <summary>
+    /// Gets the sources of the response line.
+    /// </summary>
+    /// <returns>The sources of the response line.</returns>
+    public IList<ISource> GetSources() => [];
 }

app/MindWork AI Studio/Provider/ISource.cs

@@ -0,0 +1,17 @@
+namespace AIStudio.Provider;
+
+/// <summary>
+/// Data model for a source used in the response.
+/// </summary>
+public interface ISource
+{
+    /// <summary>
+    /// The title of the source.
+    /// </summary>
+    public string Title { get; }
+    
+    /// <summary>
+    /// The URL of the source.
+    /// </summary>
+    public string URL { get; }
+}

app/MindWork AI Studio/Provider/LLMProviders.cs

@@ -14,6 +14,7 @@ public enum LLMProviders
     X = 8,
     DEEP_SEEK = 11,
     ALIBABA_CLOUD = 12,
+    PERPLEXITY = 14,
     
     FIREWORKS = 5,
     GROQ = 6,

app/MindWork AI Studio/Provider/LLMProvidersExtensions.cs

@@ -9,6 +9,7 @@ using AIStudio.Provider.Helmholtz;
 using AIStudio.Provider.HuggingFace;
 using AIStudio.Provider.Mistral;
 using AIStudio.Provider.OpenAI;
+using AIStudio.Provider.Perplexity;
 using AIStudio.Provider.SelfHosted;
 using AIStudio.Provider.X;
 using AIStudio.Settings;
@@ -38,6 +39,7 @@ public static class LLMProvidersExtensions
         LLMProviders.X => "xAI",
         LLMProviders.DEEP_SEEK => "DeepSeek",
         LLMProviders.ALIBABA_CLOUD => "Alibaba Cloud",
+        LLMProviders.PERPLEXITY => "Perplexity",
         
         LLMProviders.GROQ => "Groq",
         LLMProviders.FIREWORKS => "Fireworks.ai",
@@ -86,6 +88,8 @@ public static class LLMProvidersExtensions
         LLMProviders.DEEP_SEEK => Confidence.CHINA_NO_TRAINING.WithRegion("Asia").WithSources("https://cdn.deepseek.com/policies/en-US/deepseek-open-platform-terms-of-service.html").WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)),
         
         LLMProviders.ALIBABA_CLOUD => Confidence.CHINA_NO_TRAINING.WithRegion("Asia").WithSources("https://www.alibabacloud.com/help/en/model-studio/support/faq-about-alibaba-cloud-model-studio").WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)),
+            
+        LLMProviders.PERPLEXITY => Confidence.USA_NO_TRAINING.WithRegion("America, U.S.").WithSources("https://www.perplexity.ai/hub/legal/perplexity-api-terms-of-service").WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)),
         
         LLMProviders.SELF_HOSTED => Confidence.SELF_HOSTED.WithLevel(settingsManager.GetConfiguredConfidenceLevel(llmProvider)),
         
@@ -121,6 +125,7 @@ public static class LLMProvidersExtensions
         LLMProviders.GWDG => false,
         LLMProviders.DEEP_SEEK => false,
         LLMProviders.HUGGINGFACE => false,
+        LLMProviders.PERPLEXITY => false,
         
         //
         // Self-hosted providers are treated as a special case anyway.
@@ -165,6 +170,7 @@ public static class LLMProvidersExtensions
                 LLMProviders.X => new ProviderX(logger) { InstanceName = instanceName },
                 LLMProviders.DEEP_SEEK => new ProviderDeepSeek(logger) { InstanceName = instanceName },
                 LLMProviders.ALIBABA_CLOUD => new ProviderAlibabaCloud(logger) { InstanceName = instanceName },
+                LLMProviders.PERPLEXITY => new ProviderPerplexity(logger) { InstanceName = instanceName },
                 
                 LLMProviders.GROQ => new ProviderGroq(logger) { InstanceName = instanceName },
                 LLMProviders.FIREWORKS => new ProviderFireworks(logger) { InstanceName = instanceName },
@@ -194,6 +200,7 @@ public static class LLMProvidersExtensions
         LLMProviders.X => "https://accounts.x.ai/sign-up",
         LLMProviders.DEEP_SEEK => "https://platform.deepseek.com/sign_up",
         LLMProviders.ALIBABA_CLOUD => "https://account.alibabacloud.com/register/intl_register.htm",
+        LLMProviders.PERPLEXITY => "https://www.perplexity.ai/account/api",
      
         LLMProviders.GROQ => "https://console.groq.com/",
         LLMProviders.FIREWORKS => "https://fireworks.ai/login",
@@ -216,6 +223,7 @@ 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.PERPLEXITY => "https://www.perplexity.ai/account/api/",
         LLMProviders.HUGGINGFACE => "https://huggingface.co/settings/billing",
         
         _ => string.Empty,
@@ -232,6 +240,7 @@ public static class LLMProvidersExtensions
         LLMProviders.GOOGLE => true,
         LLMProviders.DEEP_SEEK => true,
         LLMProviders.ALIBABA_CLOUD => true,
+        LLMProviders.PERPLEXITY => true,
         LLMProviders.HUGGINGFACE => true,
         
         _ => false,
@@ -278,6 +287,7 @@ public static class LLMProvidersExtensions
         LLMProviders.X => true,
         LLMProviders.DEEP_SEEK => true,
         LLMProviders.ALIBABA_CLOUD => true,
+        LLMProviders.PERPLEXITY => true,
         
         LLMProviders.GROQ => true,
         LLMProviders.FIREWORKS => true,
@@ -299,6 +309,7 @@ public static class LLMProvidersExtensions
         LLMProviders.X => true,
         LLMProviders.DEEP_SEEK => true,
         LLMProviders.ALIBABA_CLOUD => true,
+        LLMProviders.PERPLEXITY => true,
         
         LLMProviders.GROQ => true,
         LLMProviders.FIREWORKS => true,

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

@@ -18,7 +18,7 @@ public sealed class ProviderMistral(ILogger logger) : BaseProvider("https://api.
     public override string InstanceName { get; set; } = "Mistral";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/NoProvider.cs

@@ -19,7 +19,7 @@ public class NoProvider : IProvider
     
     public Task<IEnumerable<Model>> GetEmbeddingModels(string? apiKeyProvisional = null, CancellationToken token = default) => Task.FromResult<IEnumerable<Model>>([]);
 
-    public async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatChatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatChatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         await Task.FromResult(0);
         yield break;

app/MindWork AI Studio/Provider/OpenAI/ProviderOpenAI.cs

@@ -22,7 +22,7 @@ public sealed class ProviderOpenAI(ILogger logger) : BaseProvider("https://api.o
     public override string InstanceName { get; set; } = "OpenAI";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);

app/MindWork AI Studio/Provider/OpenAI/ResponseStreamLine.cs

@@ -15,7 +15,7 @@ public readonly record struct ResponseStreamLine(string Id, string Object, uint
     public bool ContainsContent() => this != default && this.Choices.Count > 0;
 
     /// <inheritdoc />
-    public string GetContent() => this.Choices[0].Delta.Content;
+    public ContentStreamChunk GetContent() => new(this.Choices[0].Delta.Content, []);
 }
 
 /// <summary>

app/MindWork AI Studio/Provider/Perplexity/ProviderPerplexity.cs

@@ -0,0 +1,148 @@
+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.Perplexity;
+
+public sealed class ProviderPerplexity(ILogger logger) : BaseProvider("https://api.perplexity.ai/", logger)
+{
+    private static readonly Model[] KNOWN_MODELS =
+    [
+        new("sonar", "Sonar"),
+        new("sonar-pro", "Sonar Pro"),
+        new("sonar-reasoning", "Sonar Reasoning"),
+        new("sonar-reasoning-pro", "Sonar Reasoning Pro"),
+        new("sonar-deep-research", "Sonar Deep Research"),
+    ];
+    
+    #region Implementation of IProvider
+
+    /// <inheritdoc />
+    public override string Id => LLMProviders.PERPLEXITY.ToName();
+
+    /// <inheritdoc />
+    public override string InstanceName { get; set; } = "Perplexity";
+    
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<ContentStreamChunk> 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 Perplexity HTTP chat request:
+        var perplexityChatRequest = 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(perplexityChatRequest, Encoding.UTF8, "application/json");
+            return request;
+        }
+        
+        await foreach (var content in this.StreamChatCompletionInternal<ResponseStreamLine>("Perplexity", 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 this.LoadModels();
+    }
+
+    /// <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>());
+    }
+    
+    public override IReadOnlyCollection<Capability> GetModelCapabilities(Model model)
+    {
+        var modelName = model.Id.ToLowerInvariant().AsSpan();
+        
+        if(modelName.IndexOf("reasoning") is not -1 ||
+           modelName.IndexOf("deep-research") is not -1)
+            return
+            [
+                Capability.TEXT_INPUT,
+                Capability.MULTIPLE_IMAGE_INPUT,
+                
+                Capability.TEXT_OUTPUT,
+                Capability.IMAGE_OUTPUT,
+                
+                Capability.ALWAYS_REASONING,
+            ];
+        
+        return
+        [
+            Capability.TEXT_INPUT,
+            Capability.MULTIPLE_IMAGE_INPUT,
+            
+            Capability.TEXT_OUTPUT,
+            Capability.IMAGE_OUTPUT,
+        ];
+    }
+    
+    #endregion
+
+    private Task<IEnumerable<Model>> LoadModels() => Task.FromResult<IEnumerable<Model>>(KNOWN_MODELS);
+}

app/MindWork AI Studio/Provider/Perplexity/ResponseStreamLine.cs

@@ -0,0 +1,45 @@
+namespace AIStudio.Provider.Perplexity;
+
+/// <summary>
+/// Data model for a line in the response stream, for streaming completions.
+/// </summary>
+/// <param name="Id">The id of the response.</param>
+/// <param name="Object">The object describing the response.</param>
+/// <param name="Created">The timestamp of the response.</param>
+/// <param name="Model">The model used for the response.</param>
+/// <param name="SystemFingerprint">The system fingerprint; together with the seed, this allows you to reproduce the response.</param>
+/// <param name="Choices">The choices made by the AI.</param>
+public readonly record struct ResponseStreamLine(string Id, string Object, uint Created, string Model, string SystemFingerprint, IList<Choice> Choices, IList<SearchResult> SearchResults) : IResponseStreamLine
+{
+    /// <inheritdoc />
+    public bool ContainsContent() => this != default && this.Choices.Count > 0;
+
+    /// <inheritdoc />
+    public ContentStreamChunk GetContent() => new(this.Choices[0].Delta.Content, this.GetSources());
+    
+    /// <inheritdoc />
+    public bool ContainsSources() => this != default && this.SearchResults.Count > 0;
+
+    /// <inheritdoc />
+    public IList<ISource> GetSources() => this.SearchResults.Cast<ISource>().ToList();
+}
+
+/// <summary>
+/// Data model for a choice made by the AI.
+/// </summary>
+/// <param name="Index">The index of the choice.</param>
+/// <param name="Delta">The delta text of the choice.</param>
+public readonly record struct Choice(int Index, Delta Delta);
+
+/// <summary>
+/// The delta text of a choice.
+/// </summary>
+/// <param name="Content">The content of the delta text.</param>
+public readonly record struct Delta(string Content);
+
+/// <summary>
+/// Data model for a search result.
+/// </summary>
+/// <param name="Title">The title of the search result.</param>
+/// <param name="URL">The URL of the search result.</param>
+public sealed record SearchResult(string Title, string URL) : Source(Title, URL);

app/MindWork AI Studio/Provider/SelfHosted/ProviderSelfHosted.cs

@@ -18,7 +18,7 @@ public sealed class ProviderSelfHosted(ILogger logger, Host host, string hostnam
     public override string InstanceName { get; set; } = "Self-hosted";
     
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Provider.Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this, isTrying: true);

app/MindWork AI Studio/Provider/Source.cs

@@ -0,0 +1,8 @@
+namespace AIStudio.Provider;
+
+/// <summary>
+/// Data model for a source used in the response.
+/// </summary>
+/// <param name="Title">The title of the source.</param>
+/// <param name="URL">The URL of the source.</param>
+public record Source(string Title, string URL) : ISource;

app/MindWork AI Studio/Provider/SourceExtensions.cs

@@ -0,0 +1,47 @@
+using System.Text;
+
+using AIStudio.Tools.PluginSystem;
+
+namespace AIStudio.Provider;
+
+public static class SourceExtensions
+{
+    private static string TB(string fallbackEN) => I18N.I.T(fallbackEN, typeof(SourceExtensions).Namespace, nameof(SourceExtensions));
+    
+    /// <summary>
+    /// Converts a list of sources to a markdown-formatted string.
+    /// </summary>
+    /// <param name="sources">The list of sources to convert.</param>
+    /// <returns>A markdown-formatted string representing the sources.</returns>
+    public static string ToMarkdown(this IList<Source> sources)
+    {
+        var sb = new StringBuilder();
+        sb.Append("## ");
+        sb.AppendLine(TB("Sources"));
+
+        var sourceNum = 0;
+        foreach (var source in sources)
+        {
+            sb.Append($"- [{++sourceNum}] ");
+            sb.Append('[');
+            sb.Append(source.Title);
+            sb.Append("](");
+            sb.Append(source.URL);
+            sb.AppendLine(")");
+        }
+        
+        return sb.ToString();
+    }
+    
+    /// <summary>
+    /// Merges a list of added sources into an existing list of sources, avoiding duplicates based on URL and Title.
+    /// </summary>
+    /// <param name="sources">The existing list of sources to merge into.</param>
+    /// <param name="addedSources">The list of sources to add.</param>
+    public static void MergeSources(this IList<Source> sources, IList<ISource> addedSources)
+    {
+        foreach (var addedSource in addedSources)
+            if (sources.All(s => s.URL != addedSource.URL && s.Title != addedSource.Title))
+                sources.Add((Source)addedSource);
+    }
+}

app/MindWork AI Studio/Provider/X/ProviderX.cs

@@ -20,7 +20,7 @@ public sealed class ProviderX(ILogger logger) : BaseProvider("https://api.x.ai/v
     public override string InstanceName { get; set; } = "xAI";
 
     /// <inheritdoc />
-    public override async IAsyncEnumerable<string> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
     {
         // Get the API key:
         var requestedSecret = await RUST_SERVICE.GetAPIKey(this);