lspeasy / client/src / LSPClient

Type Alias: LSPClient<ClientCaps>

type LSPClient<ClientCaps> = BaseLSPClient<ClientCaps> & Transport<ClientCaps, Transport>;

Defined in: packages/client/src/client.ts:1413

Typed LSP client that connects to a language server, manages the LSP handshake, and exposes capability-aware request namespaces.

Type Parameters

Type Parameter	Default type	Description
ClientCaps extends Partial<Transport>	Transport	Client capabilities shape, defaults to ClientCapabilities.

Remarks

LSPClient handles the initialize / initialized handshake automatically on connect(). After connecting, call expect<ServerCaps>() to narrow the client type to the server's advertised capabilities, giving you typed access to namespaces like client.textDocument.hover(params).

Use When

You are embedding an LSP client inside an editor extension, a CLI tool, a test harness, or any process that connects to a language server.

Avoid When

You need to build the server end — use LSPServer from @lspeasy/server.

Never

NEVER call sendRequest before connect() completes — the transport is not attached yet and the call throws.

NEVER send requests after disconnect() is called — the transport has been closed; any pending promises will reject with a "Connection closed" error.

NEVER share one LSPClient across two separate language server processes — each process is an independent JSON-RPC peer with its own ID sequence and lifecycle state.

Throws

Error When connect() is called while already connected.

Throws

Error When sendRequest() is called before connect() completes.

See

• ClientOptions for all configuration options.
• ConnectionHealthTracker for monitoring connection liveness.

Example

import { LSPClient } from '@lspeasy/client';
import { WebSocketTransport } from '@lspeasy/core';

const client = new LSPClient({
  name: 'my-editor',
  capabilities: { textDocument: { hover: {} } },
});

const transport = new WebSocketTransport({ url: 'ws://localhost:2087' });
await client.connect(transport);

const typed = client.expect<{ hoverProvider: true }>();
const hover = await typed.textDocument.hover({
  textDocument: { uri: 'file:///src/index.ts' },
  position: { line: 0, character: 5 },
});