Language Server Protocol .NET library family

A lightweight .NET library family for building language-server-powered editors: a StreamJsonRpc LSP client, generic editor IntelliSense contracts, and a Lua provider backed by LuaLS.

What is this?

This repository is a small, focused collection of .NET libraries that make it easy to add language-server-powered IntelliSense to a text editor. Instead of coupling an editor to a single language server, the family is split into three layers:

Package	Purpose
Nickelony.LanguageServer.Abstractions	Dependency-free editor IntelliSense contracts - the stable seam between an editor and any language provider.
Nickelony.LanguageServer.Client	A lightweight LSP client built on StreamJsonRpc: spawns a language-server process and speaks LSP over stdio.
Nickelony.LanguageServer.Lua	A ready-to-use Lua provider that implements the editor contracts on top of the client and drives the real LuaLS executable.

It powers Lua IntelliSense in Tomb Editor (TombIDE.ScriptingStudio).

Features

• Editor-first contracts - completion, hover, definition, references, rename, formatting, signature help, diagnostics, and (for Lua) semantic tokens, expressed as plain editor types with zero dependency on any LSP implementation.
• Real LSP transport - process hosting, initialize handshake, capability negotiation, JSON-RPC over stdio via StreamJsonRpc.
• Robust lifecycle - automatic server restart on crash, transport versioning, graceful shutdown, and workspace re-sync after restart.
• Document tracking - full and incremental text-document synchronization, plus a workspace file watcher that forwards file changes to the server.
• Plug-and-play Lua provider - point it at a lua-language-server executable and get IntelliSense, diagnostics, and semantic coloring in your editor.

Quick start

The fastest way to get going is to reference the Lua package and host LuaLanguageServerIntelliSenseProvider in your editor:

<PackageReference Include="Nickelony.LanguageServer.Lua" Version="1.0.0-preview.1" />

using Nickelony.LanguageServer.Lua;

var provider = new LuaLanguageServerIntelliSenseProvider(
    workspaceRootDirectoryPath: @"C:\my\workspace",
    serverExecutablePath: @"C:\tools\lua-language-server\lua-language-server.exe");

provider.DiagnosticsUpdated += (filePath, diagnostics) =>
{
    // Diagnostics arrive on a background thread - marshal to your UI thread here.
    // Show them in your editor's error list / squiggles.
};

provider.OpenDocument(@"C:\my\workspace\main.lua", sourceText);

var completions = await provider.GetCompletionItemsAsync(
    @"C:\my\workspace\main.lua", sourceText, line, column);

See the Lua package README for the full example, or the Client and Abstractions READMEs for the lower layers. The consumer integration guide documents construction, disposal, event marshaling, document references, and cancellation behavior.

Architecture

┌───────────────────────────────┐
│         Your editor           │
└───────────────┬───────────────┘
                │ uses
┌───────────────▼───────────────┐
│   Nickelony.LanguageServer    │  Lua provider (ILuaIntelliSenseProvider)
│   .Lua                        │
└───────┬───────────────┬───────┘
        │               │
┌───────▼───────┐ ┌─────▼───────────────┐
│ Abstractions  │ │ Client              │  LSP over stdio (StreamJsonRpc)
│ (contracts)   │ │ (process + RPC)     │
└───────────────┘ └──────┬──────────────┘
                         │ stdio (JSON-RPC)
                 ┌───────▼──────────────┐
                 │  Language server     │  e.g. LuaLS (lua-language-server)
                 └──────────────────────┘

• Abstractions has zero package dependencies - it is a pure leaf any editor or provider can reference safely.
• Client depends on Abstractions, StreamJsonRpc, and Microsoft.Extensions.Logging.Abstractions.
• Lua depends on Abstractions + Client and shells out to an external server executable.

Requirements

• .NET 8 (all packages target net8.0, cross-platform).
• The Lua package additionally needs the lua-language-server executable at runtime (download from the LuaLS releases).

Building and testing

dotnet build Nickelony.LanguageServer.slnx
dotnet test  Nickelony.LanguageServer.slnx

The test suite covers the client and Lua provider, plus four opt-in integration tests that require a local LuaLS bundle. Run dotnet test for the current counts.

Repository layout

Nickelony.LanguageServer.Abstractions/   editor contracts (zero dependencies)
Nickelony.LanguageServer.Client/         LSP client + protocol machinery
Nickelony.LanguageServer.Lua/            Lua provider backed by LuaLS
Tests/
  Nickelony.LanguageServer.Client.Tests/
  Nickelony.LanguageServer.Lua.Tests/
  TestSupport/                           shared test logger

License

MIT © 2026 Kewin Kupilas.