feature(gpg): add more signing-keys to the config to enable my laptop as well

modules/home-manager/git.nix

@@ -1,16 +1,21 @@
-{ config, pkgs, inputs, ... }:
+{ config, lib, pkgs, inputs, ... }:
 
 let
-  # public half of ~/.ssh/id_ed25519, registered and verified as a signing key
-  # in gitea
-  signingKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHRhwzo1oxaT3fEySSmILKNnu9v30cfjx5G7FKpmfqeX aaron@argon";
+  email = "aaron@0x29a.ch";
+
+  # public half of every machine's ~/.ssh/id_ed25519, each one verified as a
+  # signing key in gitea. the key a host signs with is picked up from the key
+  # file itself, this list only tells the local git which machines to trust
+  signingKeys = [
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHRhwzo1oxaT3fEySSmILKNnu9v30cfjx5G7FKpmfqeX aaron@argon"
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGDkhvvTUcBSQdtXjX+Mw2Bp8HHhtiBm8aJi4ZxiBgZR aaron@neon"
+  ];
 in
 {
-  # gitea verifies signatures against the account key, this teaches the local
+  # gitea verifies signatures against the account keys, this teaches the local
   # git the same trust so `git log --show-signature` resolves as well
-  xdg.configFile."git/allowed_signers".text = ''
-    aaron@0x29a.ch ${signingKey}
-  '';
+  xdg.configFile."git/allowed_signers".text =
+    lib.concatMapStrings (key: "${email} ${key}\n") signingKeys;
 
   programs.git = {
     enable = true;
@@ -18,7 +23,7 @@ in
       push = { autoSetupRemote = true; };
       user = {
         name  = "aaron";
-        email = "aaron@0x29a.ch";
+        email = email;
       };
       gpg.ssh.allowedSignersFile = "${config.xdg.configHome}/git/allowed_signers";
     };