Swift — LSP setup

• Builtin server: sourcekit-lsp — sourcekit-lsp
• Extensions: .swift .objc .objcpp
• Install hint: Included with Xcode or the Swift toolchain

Install

sourcekit-lsp ships with the Swift toolchain — no separate install.

• macOS: xcode-select --install (or install full Xcode). It resolves to the active toolchain selected by xcode-select.
• Linux: Install a swift.org toolchain (sourcekit-lsp ships inside it); add the toolchain's usr/bin to PATH.
• Windows: Install the swift.org Windows toolchain; sourcekit-lsp is bundled.

Confirm it resolves:

command -v sourcekit-lsp

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):

{ "lsp": { "sourcekit-lsp": { "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. For best results the project needs a SwiftPM Package.swift or a compile_commands.json compilation database so the server can resolve modules. Pure-Xcode-project files without these resolve poorly.

Alternatives

• No mainstream alternative. sourcekit-lsp is the official Apple/swift.org server and the only practical choice.

Troubleshooting

• PATH: sourcekit-lsp on PATH; reopen shell after install (or after xcode-select -s).
• Wrong toolchain (macOS): point xcode-select at the right Xcode/toolchain; mismatches cause stale or missing results.
• No Package.swift / compile db: add a SwiftPM manifest or generate compile_commands.json for accurate indexing.
• Objective-C (.objc/.objcpp): needs a compilation database to resolve headers and frameworks.
• First build slow: the server builds the module graph on first open; wait for it.

Verify

bun ../../scripts/verify-lsp.ts path/to/File.swift