Dart — LSP setup

Builtin server: dart — dart language-server --lsp
Extensions: .dart
Install hint: Included with the Dart/Flutter SDK

Install

The language server ships inside the Dart SDK (and the Flutter SDK, which bundles Dart). There is no separate package to install — just put dart (or flutter) on PATH.

macOS: brew install dart (or install Flutter and use its bundled dart)
Linux: install the Dart SDK from your package manager / https://dart.dev/get-dart, or install Flutter
Windows: install the Dart SDK or Flutter SDK and add its bin to PATH

Confirm it resolves:

bash

command -v dart

Configure

Builtin — usually NO config needed (auto-resolved by extension). Configure only to set priority, init options, override extensions, or disable. Same JSON shape in .codex/lsp-client.json (Codex) AND .opencode/lsp.json (OpenCode/omo):

json

{ "lsp": { "dart": { "priority": 100 } } }

For builtin ids in a PROJECT config, command is supplied automatically — only set priority/initialization/extensions/disabled/env. A fully custom (non-builtin) server with its own command must go in the USER config (~/.codex/lsp-client.json).

Initialization options (only if commonly needed)

None commonly required.

Alternatives

None.

Troubleshooting

PATH: dart must be on PATH; reopen the shell after installing the SDK. Flutter users: ensure <flutter>/bin/cache/dart-sdk/bin or the Flutter bin is exported.
Flutter vs Dart: if you only have Flutter installed, the bundled dart works — make sure Flutter's bin is on PATH rather than relying on a separate Dart install.
SDK out of date: run dart --version / flutter upgrade if analysis behaves oddly on newer language features.

Verify

bash

bun ../../scripts/verify-lsp.ts path/to/file.dart