error when 'nix flake check'

[unazikx]

❯ nix flake check
warning: unknown flake output 'debug'
trace: evaluation warning: Nixpkgs 26.05 will be the last release to support x86_64-darwin; see https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.05
error:
       … while checking flake output 'checks'

       … while checking the derivation 'checks.x86_64-linux."files/readme.md"'

       … while evaluating an expression to select 'drvPath' on it
         at «internal»:1:552:
       (stack trace truncated; use '--show-trace' to show the full trace)

       error: opening file '/nix/store/501lxp0c8chziirbx1df86bdym0iz48w-source/readme.md': No such file or directory

       note: trace involved the following derivations:
       derivation 'flake-file-check'

❯ eza -1
 lib
 machines
 modules
 persystem
 flake.lock
 flake.nix
 LICENSE
󰂺 README.md

{
  perSystem =
    {
      pkgs,
      ...
    }:
    {
      files = {
        files = [
          {
            path_ = "readme.md";
            drv =
              pkgs.writeText "README.md"
                # markdown
                ''
                  hello world
                '';
          }
        ];
      };
    };
}

what i do wrong?

[unazikx]

i made touch readme.md and added to git git add readme.md and got this

❯ nix flake check
warning: unknown flake output 'debug'
trace: evaluation warning: Nixpkgs 26.05 will be the last release to support x86_64-darwin; see https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.05
warning: unknown flake output 'allSystems'
warning: unknown flake output 'homeModules'
warning: unknown flake output 'diskoConfigurations'
warning: unknown flake output 'wrappers'
warning: unknown flake output 'wrapperModules'
error: builder for '/nix/store/mhag1k0bs1z3km2l5p6sdkbsk7fi4lxj-flake-file-check.drv' failed with exit code 1;
       last 4 log lines:
       > /nix/store/6kpmfdbq5xqmykp4sv50ylrr0lkxdkv4-README.md --- Text
       > 1    hello world
       >    1 
       >
       For full logs, run:
           nix log /nix/store/mhag1k0bs1z3km2l5p6sdkbsk7fi4lxj-flake-file-check.drv

[mightyiam]

This is the check failing and showing you the difference between the expected file content and the actual file content. Use the writer that is provided as an option value to write all the files.

[mightyiam]

Let me know if you have any questions.