fix(forgejo-runner): prevent duplicate runner registrations

- Persist runner registration state by setting container working_dir to /data\n- Add post-register assertion that /opt/forgejo-runner/data/.runner exists

roles/forgejo_runner/tasks/main.yml

@@ -88,6 +88,23 @@
   when: (not forgejo_runner_registration.stat.exists) or forgejo_runner_labels_changed
   no_log: true
 
+- name: Check that runner registration state file exists after registration
+  stat:
+    path: /opt/forgejo-runner/data/.runner
+  register: forgejo_runner_registration_after
+  changed_when: false
+  when: (not forgejo_runner_registration.stat.exists) or forgejo_runner_labels_changed
+
+- name: Fail if runner registration did not persist state
+  assert:
+    that:
+      - forgejo_runner_registration_after.stat.exists
+    fail_msg: >-
+      Forgejo runner registration did not create /opt/forgejo-runner/data/.runner.
+      Without this file, the runner will re-register and Forgejo will accumulate duplicate runners.
+      Ensure the runner container writes its .runner file under /data (the persisted volume).
+  when: (not forgejo_runner_registration.stat.exists) or forgejo_runner_labels_changed
+
 - name: Persist applied Forgejo runner labels
   copy:
     dest: /opt/forgejo-runner/data/.labels

roles/forgejo_runner/templates/docker-compose.yml.j2

@@ -1,6 +1,7 @@
 services:
   runner:
     image: data.forgejo.org/forgejo/runner:11
+    working_dir: /data
     environment:
       DOCKER_HOST: unix:///var/run/docker.sock
     user: "0:0"