Editors

Zed

What you will be able to do: open a uf project in Zed and get uf's diagnostics, hover, definitions, completion, quick fixes and formatting, without vtsls's errors on Flow syntax.

What you need first: uf installed, a project with a uf.config.js, and Rust installed through rustup (Zed compiles a dev extension itself).

1. Install the extension

Zed has no setting that adds a language server of your own. A server has to come from an extension, so uf's lives in editors/zed. It is not in Zed's extension registry yet, so install it as a dev extension. uf editor install zed writes its sources to ~/.local/share/uf/editors/zed (under $XDG_DATA_HOME when that is set). Zed has no command-line install, so then open the command palette, run zed: install dev extension, and select that directory, or editors/zed in a uf checkout.

The extension starts uf lsp --cwd <worktree>, using the project's node_modules/.bin/uf before one on PATH. lsp.uf.binary.path in Zed's settings overrides both. It serves only a worktree with uf.config.js at its root. Zed's defaults ask every JavaScript server in every JavaScript project, so in a project without that file the extension declines, with a message saying why.

2. Keep vtsls off this project

uf editor setup zed writes this, keeping anything the project's file already says. By hand, commit it as .zed/settings.json in the project:

{
  "languages": {
    "JavaScript": {
      "language_servers": ["uf", "!vtsls", "!typescript-language-server", "..."],
      "formatter": { "language_server": { "name": "uf" } },
      "format_on_save": "on"
    }
  }
}

• language_servers: "uf" turns uf on, "!name" turns a server off, and "..." means every other server registered for the language, so ESLint and Tailwind keep running if the project uses them. Zed's default for JavaScript is ["!typescript-language-server", "vtsls", "..."].
• Zed's JavaScript is .js, .jsx, .mjs and .cjs. .jsx is not TSX, so this one block covers every file uf reads.
• formatter names uf explicitly. With the default "auto", Zed would pick Prettier for JavaScript. format_on_save is "off" by default.
• A project's list replaces your user list. Lists in Zed's settings do not merge. That is what makes this per project: a TypeScript project opened in the same Zed still gets vtsls from the defaults.

To stop Zed asking the uf extension in projects that are not uf projects at all, add "!uf" to languages.JavaScript.language_servers in your user settings. The project's list above names "uf" and wins.

3. Trust the project

Zed's worktree trust (restricted mode) does not start language servers that a project's .zed/settings.json asks for until you trust the project. Trust it when Zed asks, or from the restricted-mode banner.

4. Check that it worked

1. Open a file with component or match. The diagnostics panel lists only uf and flow entries.
2. The language server menu in the status bar lists uf for the buffer and not vtsls.
3. Save a file, then run uf fmt --check in a terminal. If it reports the file, Zed opened a different folder than the one that holds uf.config.js.

Editing uf.config.js needs editor: restart language server, because the server reads it once, at start-up.

What Zed does not get

Zed highlights JavaScript with a tree-sitter grammar that does not know component, hook, match or renders. No maintained tree-sitter grammar for modern Flow exists to ship instead, so those lines are highlighted as the JavaScript grammar parses them. The language features come from uf and are unaffected.

Checked against

The setting syntax, the defaults, the merge behaviour and worktree trust were read from Zed's documentation and source (assets/settings/default.json, the settings merge, trusted_worktrees) in September 2026. CI tests the extension's decisions on the host and builds its WebAssembly. No Zed runs in CI.

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