shellHook's `trap _ides_leave EXIT` breaks direnv environment capture

[wanderer]

Bug Description

When mkIdes is used in a flake devShell together with direnv's use flake, the ides shellHook sets trap _ides_leave EXIT, which overrides direnv's internal EXIT trap. Direnv relies on this trap to capture the environment state after .envrc finishes executing. With the trap overridden, direnv captures nothing — no PATH, no environment variables, nothing — making the nix dev shell completely invisible to the shell (fish, bash, zsh).

Steps to Reproduce

1. Create a flake with a devShell using mkIdes:

devShells.default = mkIdes {
  serviceDefs.foo = {
    shellCommand = "echo hello";
    systemd.remainAfterExit = true;
  };
  shellHook = ''
    export MY_VAR=hello
  '';
  packages = [ pkgs.some-tool ];
};

2. Add .envrc:

use flake

3. Run direnv allow and check what direnv exports:

direnv export json | python3 -c "import sys,json; print(sorted(json.load(sys.stdin).keys()))"

Environment

• ides: from github:manic-systems/ides (used via flake input)
• direnv: 2.37.1
• nix-direnv: 3.1.2
• OS: NixOS (linux)
• Shell: fish 3.x (also reproduces in bash)

Workaround

Save and restore direnv's EXIT trap around use flake in .envrc:

# shellcheck shell=bash
_direnv_exit_trap=$(trap -p EXIT)
use flake
eval "$_direnv_exit_trap"