Zed

Zed defines languages through extensions, so these settings treat .effeck files as TypeScript and replace the binary of Zed's TypeScript server, vtsls, with effeck. Zed then sends .effeck files with the language id typescript, which the server accepts, and the server also serves the project's .ts files. These settings are untested: Zed cannot run headlessly, so nothing has checked them in Zed.

1. Find the compiler's absolute path

From the project directory, run:

echo "$PWD/node_modules/.bin/effeck"
"$PWD/node_modules/.bin/effeck" --version

The first line is the path to use in step 2. The second command prints Effeck 0.0.1 (TypeScript 7.1.0-dev).

2. Add the project settings

Put these settings in the project's .zed/settings.json, so other TypeScript projects keep vtsls. Replace the path value with the path from step 1. If the file exists, merge these keys into it.

{
  "file_types": {
    "TypeScript": ["effeck"]
  },
  "lsp": {
    "vtsls": {
      "binary": {
        "path": "/absolute/path/to/project/node_modules/.bin/effeck",
        "arguments": ["--lsp", "--stdio"]
      }
    }
  },
  "languages": {
    "TypeScript": {
      "language_servers": ["vtsls", "!typescript-language-server", "..."]
    }
  }
}

The path must be absolute. Tell the user to open the project in Zed and check that a .effeck file shows diagnostics and hovers.