options.json derivation references flake source without string context

[blessuselessk]

Problem

When using den with NixOS configurations, nix flake check emits this warning for every NixOS configuration:

warning: Using 'builtins.derivation' to create a derivation named 'options.json' that references the store path '/nix/store/...-source' without a proper context. The resulting derivation will not have a correct store reference, so this is unreliable and may stop working in the future.

The -source store path is nixpkgs itself. The options.json derivation (NixOS options documentation) references it without proper string context, meaning nix-collect-garbage can prune it. If options.json is part of the system closure (the default when documentation.nixos.enable = true), this can make the system unbootable after gc.

Root cause

den's nixModule declares options like den.lib, den.aspects, and den.ctx with types.raw. When the NixOS module system evaluates these options to generate options.json, it serializes values that contain store path references without proper Nix string context. The resulting derivation has an informal (untracked) dependency on the nixpkgs source path.

Reproduction

Any flake using den with a NixOS configuration:

nix flake check  # warning appears for each nixosConfiguration

Workaround

Disable NixOS options documentation generation on affected hosts:

documentation.enable = false;

This removes options.json from the system closure, eliminating the gc risk. The warning still appears during evaluation but is no longer a runtime hazard.

Suggested fix

Mark the problematic options as internal/invisible so the documentation system skips them:

options.den.lib = lib.mkOption {
  type = lib.types.attrsOf lib.types.raw;
  internal = true;
  visible = false;
};

Or avoid declaring them as NixOS options entirely — set them as config values directly without corresponding option declarations.

Environment

• den rev: 7c2887a778e2263ab781acfb964a58c82ad0f324
• Nix: Determinate Nix 3.17.0
• nixpkgs: 25.11

[blessuselessk]

Additional context: this warning only surfaces on Determinate Nix (tested on 3.16.0 / nix 2.33.3), which has stricter string context tracking than community Nix. Your CI uses cachix/install-nix-action (community Nix), so the warning doesn't appear in CI logs — which is likely why this hasn't been caught before.

The problematic types.raw option declarations are at:

File	Line	Option
nix/nixModule/lib.nix	12	options.den.lib — attrsOf raw
nix/nixModule/ctx.nix	10	intoAttrsType — lazyAttrsOf (functionTo (listOf raw))
nix/nixModule/ctx.nix	13	intoFnType — functionTo (lazyAttrsOf raw)
nix/types.nix	58, 166, 182	instantiate, pkgs — raw
modules/aspects.nix	13	options.flake.denful — attrsOf raw

Adding internal = true; visible = false; to these mkOption calls should prevent the documentation system from trying to serialize them into options.json, which is what triggers the contextless store path reference.

[vic]

Please send a PR, I don't use DetNix.

[vic]

Hey, @blessuselessk

I pushed some changes using your suggestions at #289 , I don't have DetSys Nix, can you help me test this?