with inputs.devshell but without devshell.toml: error: flake 'git+file:///...' does not provide attribute 'devShells.x86_64-linux.default', ...

[devurandom]

Describe the bug

When I add inputs.devshell to my flake.nix and create the .envrc (containing use flake), but do not have a devshell.toml file, I will see an error:

$ direnv allow
direnv: loading .../.envrc
direnv: using flake
error: flake 'git+file:///...' does not provide attribute 'devShells.x86_64-linux.default', 'devShell.x86_64-linux', 'packages.x86_64-linux.default' or 'defaultPackage.x86_64-linux'
       Did you mean devShells?
direnv: nix-direnv: Evaluating current devShell failed. Falling back to previous environment!
direnv: export +NIX_DIRENV_DID_FALLBACK ~PATH

This can be worked around by creating an empty devshell.toml file:

touch devshell.toml
direnv reload

Due to nix-direnv's caching, which is not aware of the presence of devshell.toml, this problem can be easily masked by a cached direnv still existing from a previous run when devshell.toml was present.

To Reproduce

Steps to reproduce the behavior:

flake.nix:

{
  inputs = {
    ,,,
    blueprint = {
      url = "github:numtide/blueprint";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    devshell = {
      url = "github:numtide/devshell";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  ,,,
}

.envrc

#!/usr/bin/env bash
# Used by https://direnv.net

# Load `nix develop`
use flake

# Extend the environment with per-user overrides
source_env_if_exists .envrc.local

Expected behavior

When devshell.toml is missing, blueprint + devshell behave as if the file was present but empty.

System information

NixOS 25.11 and unstable