well this works at any rate

playbook.yml

@@ -0,0 +1,84 @@
+---
+- name: Upgrade FoundKey
+  hosts: localhost
+  connection: local
+  vars:
+    user: misskey
+    service: misskey
+    source_repository: /var/lib/misskey/FoundKey-0x7f
+    deploys_root: /var/lib/misskey/deploys
+    config_yml: /var/lib/misskey/default.yml
+  tasks:
+    - name: Generate deploy dir name
+      ansible.builtin.set_fact:
+        deploy_dir: "{{ deploys_root }}/{{ ansible_date_time.iso8601_basic_short }}"
+      run_once: true
+    - name: Print the generated deployment name
+      ansible.builtin.debug:
+        var: deploy_dir
+      run_once: true
+    - name: Build
+      become: true
+      become_user: "{{ user }}"
+      environment:
+        NODE_ENV: production
+      block:
+        - name: Create deployment directory
+          ansible.builtin.file:
+            path: "{{ deploy_dir }}"
+            state: directory
+            mode: '0755'
+            recurse: true
+        - name: Clone source repository
+          ansible.builtin.git:
+            repo: "{{ source_repository }}"
+            dest: "{{ deploy_dir }}"
+            single_branch: true
+        - name: Link configuration in
+          ansible.builtin.file:
+            dest: "{{ deploy_dir }}/.config/default.yml"
+            src: "{{ config_yml }}"
+            state: link
+        - name: Reflink copy previous node_modules
+          ansible.builtin.command: cp -r --reflink "{{ deploys_root }}/current/node_modules" "{{ deploy_dir }}/node_modules"
+          args:
+            creates: "{{ deploy_dir }}/node_modules"
+        - name: Install Yarn dependencies
+          ansible.builtin.command: yarn install
+          changed_when: true
+          args:
+            chdir: "{{ deploy_dir }}"
+        - name: Build FoundKey
+          ansible.builtin.command: yarn build
+          changed_when: true
+          args:
+            chdir: "{{ deploy_dir }}"
+    - name: Deploy
+      block:
+        - name: Note down previous deploy
+          become: true
+          become_user: "{{ user }}"
+          ansible.builtin.command: readlink "{{ deploys_root }}/current"
+          changed_when: true
+          register: previous_shell
+        - name: Link previous deploy
+          become: true
+          become_user: "{{ user }}"
+          ansible.builtin.file:
+            dest: "{{ deploys_root }}/previous"
+            src: "{{ previous_shell.stdout }}"
+            state: link
+            force: true
+        - name: Link new deploy
+          become: true
+          become_user: "{{ user }}"
+          ansible.builtin.file:
+            dest: "{{ deploys_root }}/current"
+            src: "{{ deploy_dir }}"
+            state: link
+            force: true
+        - name: Restart systemd service
+          become: true
+          ansible.builtin.systemd:
+            name: "{{ service }}"
+            state: restarted