this is it

.forgejo/workflows/build.yaml

@@ -18,11 +18,28 @@ jobs:
     runs-on: ${{ matrix.os }}
     env:
       PATH: ${{ format('{0}:{1}', '/run/current-system/sw/bin', env.PATH) }}
+      SSH_DIR: /home/gitea-runner/.ssh
     steps:
       - name: Checkout repository
         uses: https://github.com/actions/checkout@v4
         with:
           fetch-depth: 0
+      - name: Set up ssh key folder
+        run: |
+          mkdir -p $SSH_DIR
+          chmod 700 $SSH_DIR
+      - name: Write ssh key
+        id: sshkey
+        uses: https://github.com/timheuer/base64-to-file@v1
+        with:
+          encodedString: "${{ secrets.SSH_USER }}"
+          fileName: id_ed25519
+          fileDir: /home/gitea-runner/.ssh/
+      - name: Make id_ed25519 user only
+        shell: bash
+        run: |
+          chmod 600 $SSH_DIR/id_ed25519
+        
       - uses: https://github.com/cachix/cachix-action@v15
         if: ${{ !github.event.pull_request.head.repo.fork }}
         with: