NOpenCode

A .NET SDK for OpenCode — the open-source terminal AI coding assistant.

NOpenCode lets you control OpenCode from C# with a plain-English API. It auto-manages the opencode serve process, so you can focus on your code.

Features

• Zero setup — auto-discovers or starts opencode serve for you
• Plain-English API — reads like natural language
• Multi-turn sessions — ask follow-up questions in context
• Streaming — receive responses chunk by chunk
• File & code search — ripgrep, filename lookup, symbol search
• Session management — fork, share, diff, revert, summarize
• Provider & model discovery — list available models, providers, agents
• MCP server management — add and list MCP servers
• Event monitoring — subscribe to real-time SSE events
• DI integration — AddNOpenCode() for ASP.NET Core / console hosts
• .NET Standard 2.0 — compatible with .NET Framework 4.6.1+ and all modern .NET

Prerequisites

• OpenCode CLI installed (npm install -g @opencode/cli)
• .NET SDK 8+ (for consumption) or .NET 10 (for development)

Installation

dotnet add package NOpenCode

Quick Start

using NOpenCode;

string answer = await OpenCode.Ask("Explain how async/await works in C#");
Console.WriteLine(answer);

Examples

One-shot with configuration

string review = await OpenCode.Ask(
    "Review this code for potential bugs.",
    cfg => cfg
        .WithModel("opencode/deepseek-v4-flash-free")
        .InDirectory(@"./src")
);

// Or use the builder for full control
await using var ai = await OpenCode
    .Configure()
    .WithModel("opencode/deepseek-v4-flash-free")
    .Launch();

var reply = await ai
    .Ask("What improvements would you suggest?")
    .WithFiles("Program.cs", "Utils.cs")
    .Execute();

Console.WriteLine(reply);

Multi-turn conversation

await using var ai = await OpenCode
    .Configure()
    .WithModel("opencode/mimo-v2.5-free")
    .Launch();

var session = await ai.NewSession("Architecture review").Create();

var r1 = await session.Ask("What is the high-level architecture?");
var r2 = await session.Ask("Where are the main entry points?");

Streaming

await session.AskStream(
    "Write a README for this project.",
    onChunk: chunk => Console.Write(chunk),
    onComplete: reply => Console.WriteLine($"\nDone, tokens: {reply.Usage?.Total}"),
    onError: ex => Console.WriteLine($"Error: {ex.Message}")
);

Session lifecycle

var session = await ai.NewSession("Bug analysis").Create();

// Fork into a new branch
var fork = await session.Fork();
await fork.Ask("Focus on security issues only.");

// Get the diff
var diff = await fork.GetDiff();
foreach (var d in diff)
    Console.WriteLine($"[{d.Type}] {d.Path}");

// Share the session
await fork.Share();

// Clean up
await fork.Delete();

File & code search

var todos = await ai.Files.Search("TODO|FIXME");
foreach (var match in todos)
    Console.WriteLine($"{match.Path}:{match.LineNumber}  {match.Lines?.Trim()}");

var files = await ai.Files.Find("*.cs");
var content = await ai.Files.Read("Program.cs");

Discovery

var models = await ai.Models.List("opencode");
var providers = await ai.Providers.List();
var agents = await ai.Agents.List();
var health = await ai.Diagnostics.GetHealth();

MCP server management

await ai.Mcp.Add("filesystem", new
{
    command = "npx",
    args = new[] { "-y", "@modelcontextprotocol/server-filesystem", "./" }
});

var servers = await ai.Mcp.List();

DI integration

builder.Services.AddNOpenCode(cfg => cfg
    .WithModel("opencode/minimax-m3")
);

public class ReviewService(OpenCodeClient AI)
{
    public async Task RunAsync()
    {
        var reply = await AI
            .Ask("Review the latest changes")
            .Execute();
    }
}

Real-time events

await ai.Events.Subscribe(
    onEvent: evt => Console.WriteLine($"[{evt.Type}] {evt.Data}"),
    onError: ex => Console.WriteLine($"Error: {ex.Message}")
);

Project Structure

src/NOpenCode/              → .NET Standard 2.0 library
  OpenCode.cs               → Static entry point
  NOpenCodeBuilder.cs       → Fluent builder
  OpenCodeClient.cs         → Main client with 11 sub-clients
  OpenCodeSession.cs        → Session with full lifecycle
  AskOperation.cs           → One-shot query builder
  SessionBuilder.cs         → Session creation builder
  ServerManager.cs          → Auto-manages opencode serve
  Clients/                  → Domain-specific clients
  Models/                   → 14 DTOs
  Http/                     → HTTP client + SSE reader
  DependencyInjection/      → IServiceCollection extensions
  Exceptions/               → Custom exception hierarchy

examples/                   → 10 example projects (net10.0)
  01-HelloWorld
  02-OneShot
  03-MultiTurn
  04-Streaming
  05-DI
  06-SessionLifecycle
  07-FileSearch
  08-Discovery
  09-McpManagement
  10-EventMonitor

tests/NOpenCode.Tests/      → xUnit tests

License

MIT