bug: services.gpg-agent.enableSshSupport doesn't respect programs.gpg.homedir option

Are you following the right branch?

[X] My Nixpkgs and Home Manager versions are in sync

Is there an existing issue for this?

[X] I have searched the existing issues

Issue description

Problem

services.gpg-agent.enableSshSupport doesn't respect programs.gpg.homedir option. gpg-agent can't find the public key even though it was already imported.

gpgconf shows the correct home directory location.

% gpgconf --list-dirs
sysconfdir:/etc/gnupg
bindir:/nix/store/859l6kcc0swh01xpngxs9fjqr7mv50hp-gnupg-2.4.1/bin
libexecdir:/nix/store/859l6kcc0swh01xpngxs9fjqr7mv50hp-gnupg-2.4.1/libexec
libdir:/nix/store/859l6kcc0swh01xpngxs9fjqr7mv50hp-gnupg-2.4.1/lib/gnupg
datadir:/nix/store/859l6kcc0swh01xpngxs9fjqr7mv50hp-gnupg-2.4.1/share/gnupg
localedir:/nix/store/859l6kcc0swh01xpngxs9fjqr7mv50hp-gnupg-2.4.1/share/locale
socketdir:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6
dirmngr-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.dirmngr
keyboxd-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.keyboxd
agent-ssh-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.gpg-agent.ssh
agent-extra-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.gpg-agent.extra
agent-browser-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.gpg-agent.browser
agent-socket:/run/user/1000/gnupg/d.rkqjarkduajeyyh6cbii3pf6/S.gpg-agent
homedir:/home/user/.config/gnupg

Result

~ % ssh -T git@github.com
git@github.com: Permission denied (publickey).

Example

programs.gpg = {
  enable = true;
  homedir = "/home/user/.config/gnupg";
};

services.gpg-agent = {
  enable = true;
  enableZshIntegration = true;
  enableSshSupport = true;
  pinentryFlavor = "curses";
  sshKeys = [
    # random keygrip strings that I generated for illustrated purpose
    "LWL7FJ7J32LUJJ4IBSGRQPMZVMMTIJOP751MLVPA"
    "DCTTAOWJTTTO07U2PUCPTKVSFQY5BCQ3QFYZSELE" 
  ];
};

Current Solution

Remove programs.gpg.homedir option and use default .gnupg folder location.

Possibly related issue

https://github.com/nix-community/home-manager/issues/4637

Maintainer CC

@rycee

System information

~ % nix-info -m                                                         
 - system: `"x86_64-linux"`
 - host os: `Linux 6.1.65, NixOS, 24.05 (Uakari), 24.05.20231204.2c7f3c0`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.1`
 - channels(root): `""`
 - channels(user): `""`
 - nixpkgs: `/nix/store/aiv01710wqn2b7hms2253d1cq89kdzh8-source`

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nix-community / home-manager