nixd is a feature-rich Nix language server that interoperates with the C++ Nix
implementation.  By linking against the Nix library it provides:

  - Nixpkgs option support for NixOS, home-manager and flake-parts.
  - Lazy, evaluated Nixpkgs package completion.
  - Shared evaluation caches (flake, file) with the system Nix install.
  - Cross-file analysis such as goto-definition into nixpkgs.

WWW: https://github.com/nix-community/nixd