Use config name by default, falling back to attr name

nixos/modules/services/continuous-integration/github-runner/options.nix

@@ -55,19 +55,23 @@ with lib;
     example = "/run/secrets/github-runner/nixos.token";
   };
 
-  name = mkOption {
+  name = let
     # Same pattern as for `networking.hostName`
-    type = types.strMatching "^$|^[[:alnum:]]([[:alnum:]_-]{0,61}[[:alnum:]])?$";
+    baseType = types.strMatching "^$|^[[:alnum:]]([[:alnum:]_-]{0,61}[[:alnum:]])?$";
+  in mkOption {
+    type = if includeNameDefault then baseType else types.nullOr baseType;
     description = lib.mdDoc ''
       Name of the runner to configure. Defaults to the hostname.
 
       Changing this option triggers a new runner registration.
     '';
     example = "nixos";
-  } // lib.optionalAttrs includeNameDefault {
+  } // (if includeNameDefault then {
     default = config.networking.hostName;
     defaultText = literalExpression "config.networking.hostName";
-  };
+  } else {
+    default = null;
+  });
 
   runnerGroup = mkOption {
     type = types.nullOr types.str;

nixos/modules/services/continuous-integration/github-runners.nix

@@ -15,7 +15,7 @@ in
   options.services.github-runners = mkOption {
     default = {};
     type = with types; attrsOf (submodule { options = import ./github-runner/options.nix (args // {
-      # services.github-runners.${name}.name doesn't have a default; instead it is set to ${name} below.
+      # services.github-runners.${name}.name doesn't have a default; it falls back to ${name} below.
       includeNameDefault = false;
     }); });
     example = {
@@ -39,15 +39,17 @@ in
   };
 
   config = {
-    systemd.services = flip mapAttrs' cfg (name: v:
+    systemd.services = flip mapAttrs' cfg (n: v:
       let
-        svcName = "github-runner-${name}";
+        svcName = "github-runner-${n}";
       in
         nameValuePair svcName
         (import ./github-runner/service.nix (args // {
           inherit svcName;
-          cfg = v // { inherit name; };
-          systemdDir = "github-runner/${name}";
+          cfg = v // {
+            name = if v.name != null then v.name else n;
+          };
+          systemdDir = "github-runner/${n}";
         }))
     );
   };