Universal.DeepSeek.Client 1.0.2

Universal.DeepSeek.Client

A typed .NET client for DeepSeek's REST API. It supports chat completions, reasoning, tools, JSON output, SSE streaming, beta FIM completions, model listing, and account balance.

Quick start

using Universal.DeepSeek.Client;
using Universal.DeepSeek.Client.V1.Chat;

using var client = new DeepSeekClient("your-api-key");
var response = await client.V1.Chat.CreateCompletionAsync(new CreateCompletionRequest
{
    Model = Models.DeepSeekV41Flash,
    Messages = new Message[]
    {
        new SystemMessage("You are a helpful assistant."),
        new UserMessage("Hello!")
    },
    Thinking = ThinkingConfiguration.Enabled,
    ReasoningEffort = ReasoningEfforts.High
});

Console.WriteLine(response.Choices[0].Message.Content);

Streaming

await foreach (var chunk in client.V1.Chat.CreateCompletionStreamingAsync(
    new CreateCompletionRequest
    {
        Model = Models.DeepSeekV41Flash,
        Messages = new Message[] { new UserMessage("Explain monads simply.") },
        Stream = true,
        StreamOptions = new StreamOptions { IncludeUsage = true }
    }))
{
    Console.Write(chunk.Choices?[0]?.Delta?.Content);
}

The parser implements SSE framing, ignores DeepSeek keep-alive comments, supports multi-line data events, and stops at [DONE]. Use CreateCompletionStreamingRawAsync when relaying the HTTP stream directly.

Reasoning and tool calls

DeepSeek requires reasoning_content from an assistant tool-call turn to be sent back on subsequent requests in thinking mode. The response deserializes to AssistantMessage, so the same message can be appended directly:

var assistant = response.Choices[0].Message;
var followUp = await client.V1.Chat.CreateCompletionAsync(new CreateCompletionRequest
{
    Model = Models.DeepSeekV41Flash,
    Thinking = ThinkingConfiguration.Enabled,
    Messages = new Message[]
    {
        new UserMessage("What is the weather in Sydney?"),
        assistant,
        new ToolMessage("{\"temperature\":18}", assistant.ToolCalls[0].Id)
    },
    Tools = tools
});

When thinking is enabled, use ToolChoiceOptions.Auto; the live API rejects a forced named function choice in that mode.

Strict tool schemas and chat prefix completion are beta features. Construct a resource client with a beta base URI when using them:

using var betaChat = new ChatClient(new Uri("https://api.deepseek.com/beta/"), "your-api-key");

FIM completion

client.V1.Completions automatically uses https://api.deepseek.com/beta/completions:

var fim = await client.V1.Completions.CreateCompletionAsync(
    new Universal.DeepSeek.Client.V1.Completions.CreateCompletionRequest
    {
        Model = Models.DeepSeekV41Flash,
        Prompt = "def fib(a):",
        Suffix = "\n    return fib(a - 1) + fib(a - 2)"
    });

API failures are surfaced as Universal.Common.Net.Http.HttpException, consistently with the other Universal.* clients.