Add conditional restart support to 7 roles that previously always restarted

Replace hardcoded restart_necessary: true with computed values for:
conduit, continuwuity, dendrite, element-call, media-repo,
appservice-kakaotalk, and wechat.

Each role now registers results from config, support files, systemd service,
and docker image pull tasks, then computes a restart_necessary variable
from their combined .changed state. group_vars/matrix_servers is updated
to reference these variables instead of hardcoding true.

For dendrite, the systemd service template was also separated out of the
combined support-files with_items loop so it can be independently tracked.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

roles/custom/matrix-dendrite/defaults/main.yml

@@ -361,3 +361,13 @@ matrix_dendrite_media_api_max_thumbnail_generators: 10
 
 # Controls whether the full-text search engine is enabled
 matrix_dendrite_sync_api_search_enabled: false
+
+# matrix_dendrite_restart_necessary controls whether the service
+# will be restarted (when true) or merely started (when false) by the
+# systemd service manager role (when conditional restart is enabled).
+#
+# This value is automatically computed during installation based on whether
+# any configuration files, the systemd service file, or the container image changed.
+# The default of `false` means "no restart needed" — appropriate when the role's
+# installation tasks haven't run (e.g., due to --tags skipping them).
+matrix_dendrite_restart_necessary: false

roles/custom/matrix-dendrite/tasks/setup_install.yml

@@ -55,10 +55,10 @@
     force_source: "{{ matrix_dendrite_container_image_force_pull if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
     force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_dendrite_container_image_force_pull }}"
   when: "not matrix_dendrite_container_image_self_build | bool"
-  register: result
+  register: matrix_dendrite_container_image_pull_result
   retries: "{{ devture_playbook_help_container_retries_count }}"
   delay: "{{ devture_playbook_help_container_retries_delay }}"
-  until: result is not failed
+  until: matrix_dendrite_container_image_pull_result is not failed
 
 # We do this so that the signing key would get generated.
 # We don't use the `docker_container` module, because using it with `cap_drop` requires
@@ -89,6 +89,7 @@
     mode: '0644'
     owner: "{{ matrix_user_name }}"
     group: "{{ matrix_group_name }}"
+  register: matrix_dendrite_config_result
 
 - when: "matrix_dendrite_container_image_self_build | bool"
   block:
@@ -139,6 +140,21 @@
     - src: bin/create-account.j2
       dest: "{{ matrix_dendrite_bin_path }}/create-account"
       mode: "0750"
-    - src: systemd/matrix-dendrite.service.j2
-      dest: "{{ devture_systemd_docker_base_systemd_path }}/matrix-dendrite.service"
-      mode: "0644"
+  register: matrix_dendrite_support_files_result
+
+- name: Ensure matrix-dendrite.service installed
+  ansible.builtin.template:
+    src: "{{ role_path }}/templates/systemd/matrix-dendrite.service.j2"
+    dest: "{{ devture_systemd_docker_base_systemd_path }}/matrix-dendrite.service"
+    mode: '0644'
+  register: matrix_dendrite_systemd_service_result
+
+- name: Determine whether Dendrite needs a restart
+  ansible.builtin.set_fact:
+    matrix_dendrite_restart_necessary: >-
+      {{
+        matrix_dendrite_config_result.changed | default(false)
+        or matrix_dendrite_support_files_result.changed | default(false)
+        or matrix_dendrite_systemd_service_result.changed | default(false)
+        or matrix_dendrite_container_image_pull_result.changed | default(false)
+      }}