Add AST-extracted metadata from .nix module files to a srctree filesystem tree using nix-meta.

Embed metadata (descriptions, author info, version numbers) in your Nix modules without affecting the evaluated configuration. _meta is stripped before the module reaches evaluation.

1. Parse — nix-meta parses .nix files at the AST level and extracts the top-level _meta attribute set.
2. Strip — _meta is removed from each AST, then the modified AST is rendered to temporary files.
3. Load — srctree evaluates the stripped files.
4. Enrich — The evaluated content and extracted metadata are merged into the final metatree.

Add metatree-nix to your flake.nix inputs:

{
  inputs.metatree.url = "github:z1-0/metatree-nix";

  outputs = { metatree, ... }: {
    lib = metatree.lib;
  };
}

Add a top-level _meta attribute set to your module files:

# src/services/web.nix
{
  _meta = {
    description = "Web server service module";
    author = "team-infra";
    version = 1;
  };

  port = 8080;
  host = "0.0.0.0";
  workers = 4;
}

let
  pkgs = import nixpkgs { system = "x86_64-linux"; };
  metatree = metatree.lib.load pkgs ./src;
in
  metatree

• load — Returns enriched tree structure directly.
• loadHaumea — Returns { tree, attrs } for haumea-style access.

{
  name = "web";
  path = "/abs/path/to/src/services/web.nix";
  type = "file";
  content = {
    port = 8080;
    host = "0.0.0.0";
    workers = 4;
  };
  meta = {
    description = "Web server service module";
    author = "team-infra";
    version = 1;
  };
}

load :: pkgs -> src -> tree

Load a directory with srctree, extract _meta from Nix files, strip it, evaluate, and return the enriched tree.

• pkgs — Package set for running parser/renderer utilities.
• src — Source directory to load.

loadHaumea :: pkgs -> args -> { tree, attrs }

Load with haumea-style return, providing both tree and clean attrs.

• pkgs — Package set for running parser/renderer utilities.
• args — Arguments forwarded to srctree.lib.loadHaumea.

withMeta :: pkgs -> tree -> tree

Enrich an already loaded srctree tree with AST-extracted _meta attributes.

• pkgs — Package set for running parser/renderer utilities.
• tree — A srctree tree structure to enrich.