diff --git a/CHANGELOG.md b/CHANGELOG.md
index fcf3768..206e532 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ module follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Added
 
+- An externally provisioned runner account whose primary group is named differently from the account now converges on the first apply: the new optional `runner_account.group` names the account's primary group and feeds every group ownership the module manages. It defaults to the account name, so existing hosts are unchanged.
 - A Hiera data check ships with the module: it fails on any data key that no deployed class declares, instead of Hiera silently ignoring it, and flags subkeys set under a disabled `manage` toggle with a non-failing advisory.
 
 ### Changed
diff --git a/README.md b/README.md
index bd30dee..e004bd4 100644
--- a/README.md
+++ b/README.md
@@ -283,16 +283,24 @@ dependencies; the example skeleton carries the lines).
 
 #### `runner_account`
 
-The OS account the runner manager and the rootless daemon run as: `name`, `uid`, and `home`,
-with `manage` deciding ownership. The identity keys are read by every concern even when
-`manage: false` (socket derivation, file ownership, service `ExecStart`); the toggle only
-decides whether the module creates and enforces the group, user, and home. Keep `manage` off
-where another configuration-management system owns the account; two owners would fight over
+The OS account the runner manager and the rootless daemon run as: `name`, an optional `group`,
+`uid`, and `home`, with `manage` deciding ownership. The identity keys are read by every concern
+even when `manage: false` (socket derivation, file ownership, service `ExecStart`); the toggle
+only decides whether the module creates and enforces the group, user, and home. Keep `manage`
+off where another configuration-management system owns the account; two owners would fight over
 it. The subordinate UID/GID ranges rootless Docker needs are owned by
 [`rootless_docker`](#rootless_docker), not this toggle. Home internals (`.ssh`, `.config`) are
 never managed, beyond the no-detach-netns drop-in the module places under
 `~/.config/systemd/user/`.
 
+`group` names the account's primary group and defaults to `name`. Set it for an externally
+provisioned account whose primary group is named differently (e.g. account `ci-worker`, group `ci`):
+it feeds every group ownership the module manages — the group resource and the user's primary
+group where `manage` is on, and the group of the runner configuration file, its directory, and
+the account's systemd user tree — so the first apply converges instead of failing to resolve a
+group that does not exist. Left unset, the account name doubles as the group, which is correct
+by construction where the module creates the account.
+
 #### `rootless_docker`
 
 With `rootless_docker.manage` on, the module brings up the rootless-Docker user daemon:
diff --git a/REFERENCE.md b/REFERENCE.md
index a6a341a..26c2ece 100644
--- a/REFERENCE.md
+++ b/REFERENCE.md
@@ -175,7 +175,8 @@ Struct[{
 ```
 
 The rendered runner configuration file (GitLab Runner's `config.toml`).
-Owner and group derive from `runner_account.name`; the mode is fixed 0600
+Owner derives from `runner_account.name` and group from
+`runner_account.group` (which defaults to the name); the mode is fixed 0600
 (the file carries the runner tokens).
 
 Options:
@@ -190,6 +191,7 @@ Data type:
 Struct[{
     manage => Boolean,
     name   => Rootless_gitlab_runner::Username,
+    group  => Optional[Rootless_gitlab_runner::Username],
     uid    => Optional[Integer[1]],
     home   => Stdlib::Absolutepath,
   }]
@@ -207,6 +209,13 @@ configuration-management system owns the account. The subordinate UID/GID
 ranges rootless docker needs are owned by `rootless_docker.manage`.
 Default false.
 * **:name** `Rootless_gitlab_runner::Username`: Username of the runner account. Default `gitlab-runner`.
+* **:group** `Optional[Rootless_gitlab_runner::Username]`: Name of the account's primary group. Defaults to the account name (the
+data layer cannot express that default, so an unset key falls back to
+`name` in code). Set it for an externally provisioned account whose primary
+group is named differently (e.g. account `ci-worker`, group `ci`): it feeds
+every group ownership the module manages — the group resource and the
+user's primary group where `manage` is on, and the group of the runner
+configuration file, its directory, and the account's systemd user tree.
 * **:uid** `Optional[Integer[1]]`: Numeric uid of the runner account. No default: the uid is host data, not
 something a module can sensibly invent. It derives the rootless runtime
 paths (`/run/user/<uid>`, the docker socket) and is enforced on the user
diff --git a/data/common.yaml b/data/common.yaml
index 8d5035a..1a51c41 100644
--- a/data/common.yaml
+++ b/data/common.yaml
@@ -60,6 +60,7 @@ rootless_gitlab_runner::configuration_file:
 rootless_gitlab_runner::runner_account:
   manage: false
   name: 'gitlab-runner'
+  group: ~
   uid: ~
   home: '/home/gitlab-runner'
 
diff --git a/manifests/config.pp b/manifests/config.pp
index 6742a70..8029fff 100644
--- a/manifests/config.pp
+++ b/manifests/config.pp
@@ -4,6 +4,9 @@
   assert_private()
 
   $runner_name = $rootless_gitlab_runner::runner_account['name']
+  # Primary group, defaulting to the account name (derived in init.pp). Owners
+  # stay the account name; only the group ownerships derive from it.
+  $runner_group = $rootless_gitlab_runner::runner_group
   $runner_home = $rootless_gitlab_runner::runner_account['home']
   $configuration_file_path = $rootless_gitlab_runner::configuration_file['path']
 
@@ -87,7 +90,7 @@
     file { $config_dir:
       ensure => directory,
       owner  => 'root',
-      group  => $runner_name,
+      group  => $runner_group,
       mode   => '0770',
     }
 
@@ -104,7 +107,7 @@
     file { "${config_dir}/.runner_system_id":
       ensure => file,
       owner  => $runner_name,
-      group  => $runner_name,
+      group  => $runner_group,
       mode   => '0600',
     }
   }
@@ -118,7 +121,7 @@
   file { $configuration_file_path:
     ensure  => file,
     owner   => $runner_name,
-    group   => $runner_name,
+    group   => $runner_group,
     mode    => '0600',
     content => Sensitive(epp('rootless_gitlab_runner/config.toml.epp', {
       'concurrent'         => $rootless_gitlab_runner::concurrent,
@@ -145,7 +148,7 @@
   file { [$user_config_dir, $user_systemd_dir, $user_units_dir, $dropin_dir]:
     ensure => directory,
     owner  => $runner_name,
-    group  => $runner_name,
+    group  => $runner_group,
     mode   => '0755',
   }
 
@@ -155,7 +158,7 @@
   file { $dropin_path:
     ensure  => file,
     owner   => $runner_name,
-    group   => $runner_name,
+    group   => $runner_group,
     mode    => '0644',
     source  => 'puppet:///modules/rootless_gitlab_runner/no-detach-netns.conf',
     require => File[$dropin_dir],
diff --git a/manifests/init.pp b/manifests/init.pp
index 09184d4..643bf1c 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -93,7 +93,8 @@
 #   and never managed. Default `/etc/gitlab-runner-infra`.
 # @param configuration_file
 #   The rendered runner configuration file (GitLab Runner's `config.toml`).
-#   Owner and group derive from `runner_account.name`; the mode is fixed 0600
+#   Owner derives from `runner_account.name` and group from
+#   `runner_account.group` (which defaults to the name); the mode is fixed 0600
 #   (the file carries the runner tokens).
 # @option configuration_file [Stdlib::Absolutepath] :path
 #   Where the file is written. Default `/etc/gitlab-runner/config.toml`.
@@ -109,6 +110,14 @@
 #   Default false.
 # @option runner_account [Rootless_gitlab_runner::Username] :name
 #   Username of the runner account. Default `gitlab-runner`.
+# @option runner_account [Optional[Rootless_gitlab_runner::Username]] :group
+#   Name of the account's primary group. Defaults to the account name (the
+#   data layer cannot express that default, so an unset key falls back to
+#   `name` in code). Set it for an externally provisioned account whose primary
+#   group is named differently (e.g. account `ci-worker`, group `ci`): it feeds
+#   every group ownership the module manages — the group resource and the
+#   user's primary group where `manage` is on, and the group of the runner
+#   configuration file, its directory, and the account's systemd user tree.
 # @option runner_account [Optional[Integer[1]]] :uid
 #   Numeric uid of the runner account. No default: the uid is host data, not
 #   something a module can sensibly invent. It derives the rootless runtime
@@ -229,6 +238,7 @@
   Struct[{
     manage => Boolean,
     name   => Rootless_gitlab_runner::Username,
+    group  => Optional[Rootless_gitlab_runner::Username],
     uid    => Optional[Integer[1]],
     home   => Stdlib::Absolutepath,
   }]                               $runner_account,
@@ -291,6 +301,15 @@
     ]))
   }
 
+  # The account's primary group, derived once and read as a group by every
+  # concern (the group resource and the user's gid in user.pp, and every
+  # managed file's group in config.pp). The data layer cannot express "same as
+  # the account name", so the default is an absent key and the fallback lives
+  # here: an unset group follows the account name — correct by construction
+  # where the module creates the account — while a set group names the
+  # differently named primary group of an externally provisioned account.
+  $runner_group = pick($runner_account['group'], $runner_account['name'])
+
   # Defaults merged under every runner entry; keys set on the entry win.
   $effective_runners = $runners.map |$r| { $runner_defaults + $r }
 
diff --git a/manifests/user.pp b/manifests/user.pp
index b026dad..7aaab10 100644
--- a/manifests/user.pp
+++ b/manifests/user.pp
@@ -6,9 +6,11 @@
   $account = $rootless_gitlab_runner::runner_account
 
   if $account['manage'] {
-    $runner_name = $account['name']
+    $runner_name  = $account['name']
+    # Primary group, defaulting to the account name (derived in init.pp).
+    $runner_group = $rootless_gitlab_runner::runner_group
 
-    group { $runner_name:
+    group { $runner_group:
       ensure => present,
       system => true,
     }
@@ -19,11 +21,11 @@
       ensure     => present,
       system     => true,
       uid        => $account['uid'],
-      gid        => $runner_name,
+      gid        => $runner_group,
       home       => $account['home'],
       managehome => true,
       shell      => '/bin/bash',
-      require    => Group[$runner_name],
+      require    => Group[$runner_group],
     }
   }
 }
diff --git a/spec/classes/rootless_gitlab_runner_spec.rb b/spec/classes/rootless_gitlab_runner_spec.rb
index 26bceb8..17c88a4 100644
--- a/spec/classes/rootless_gitlab_runner_spec.rb
+++ b/spec/classes/rootless_gitlab_runner_spec.rb
@@ -438,14 +438,15 @@ def struct_param(name, overrides = {})
     it { is_expected.to compile.with_all_deps }
     it { is_expected.to contain_group('gitlab-runner').with('ensure' => 'present', 'system' => true) }
 
-    it 'owns the user with the declared uid and home' do
+    it 'owns the user with the declared uid and home, primary group defaulting to the name' do
       is_expected.to contain_user('gitlab-runner').with(
         'ensure'     => 'present',
         'system'     => true,
         'uid'        => 4242,
+        'gid'        => 'gitlab-runner',
         'home'       => '/home/gitlab-runner',
         'managehome' => true,
-      )
+      ).that_requires('Group[gitlab-runner]')
     end
 
     %w[subuid subgid].each do |f|
@@ -455,6 +456,23 @@ def struct_param(name, overrides = {})
     end
   end
 
+  # runner_account.group names the account's primary group; unset it defaults
+  # to the account name. With manage on, the module creates that group and sets
+  # it as the user's primary group instead of a same-named group.
+  context 'with runner_account.manage and a differently named primary group' do
+    let(:params) do
+      { 'runner_account' => struct_param('runner_account', 'manage' => true, 'uid' => 4242, 'group' => 'ci') }
+    end
+
+    it { is_expected.to compile.with_all_deps }
+
+    it 'creates the named group and sets it as the user primary group, not the account name' do
+      is_expected.to contain_group('ci').with('ensure' => 'present', 'system' => true)
+      is_expected.not_to contain_group('gitlab-runner')
+      is_expected.to contain_user('gitlab-runner').with('gid' => 'ci').that_requires('Group[ci]')
+    end
+  end
+
   context 'with rootless_docker.manage' do
     let(:params) do
       { 'rootless_docker' => struct_param('rootless_docker', 'manage' => true),
@@ -708,6 +726,32 @@ def struct_param(name, overrides = {})
         .with_content(%r{^ExecStart=/usr/bin/gitlab-runner run --working-directory /srv/ci-worker --config /etc/gitlab-runner/config\.toml --service gitlab-runner$})
         .with_content(%r{^Environment=DOCKER_HOST=unix:///run/user/5000/docker\.sock$})
     end
+
+    # An externally provisioned account (manage off) whose primary group is
+    # named differently. Every managed group ownership must derive from the
+    # group, while owners stay the account name — otherwise the first apply
+    # fails to resolve a group that does not exist.
+    context 'with a differently named primary group' do
+      let(:params) do
+        super().merge('runner_account' => struct_param('runner_account',
+                                                       'name' => 'ci-worker', 'uid' => 5000,
+                                                       'home' => '/srv/ci-worker', 'group' => 'ci'))
+      end
+
+      it { is_expected.to compile.with_all_deps }
+
+      it 'derives every managed group ownership from the group, owners staying the account name' do
+        is_expected.to contain_file('/etc/gitlab-runner/config.toml')
+          .with('owner' => 'ci-worker', 'group' => 'ci')
+        is_expected.to contain_file('/etc/gitlab-runner').with('group' => 'ci')
+        is_expected.to contain_file('/etc/gitlab-runner/.runner_system_id')
+          .with('owner' => 'ci-worker', 'group' => 'ci')
+        is_expected.to contain_file('/srv/ci-worker/.config/systemd/user')
+          .with('owner' => 'ci-worker', 'group' => 'ci')
+        is_expected.to contain_file('/srv/ci-worker/.config/systemd/user/docker.service.d/no-detach-netns.conf')
+          .with('owner' => 'ci-worker', 'group' => 'ci')
+      end
+    end
   end
 
   context 'with standalone.manage alone (no self-update loop)' do