diff --git a/.gitea/workflows/renovate-pr-deploy.yml b/.gitea/workflows/renovate-pr-deploy.yml
index 4cffda39..63550c01 100644
--- a/.gitea/workflows/renovate-pr-deploy.yml
+++ b/.gitea/workflows/renovate-pr-deploy.yml
@@ -51,16 +51,21 @@ jobs:
       - name: Get changed services from docker-compose.yml
         id: services
         run: |
+          set -euo pipefail
+
           git fetch origin ${{ github.event.pull_request.base.ref }}
 
-          # Extract service=image pairs from HEAD (PR merge result)
+          # Extract service=image pairs from HEAD (current merge commit)
           yq -r '.services | to_entries[] | "\(.key)=\(.value.image // "")"' docker-compose.yml \
             | sort > services_head.txt
 
           # Extract service=image pairs from BASE (main branch)
-          git show origin/${{ github.event.pull_request.base.ref }}:docker-compose.yml \
-            | yq -r '.services | to_entries[] | "\(.key)=\(.value.image // "")"' \
-            | sort > services_main.txt || true
+          if git show origin/${{ github.event.pull_request.base.ref }}:docker-compose.yml > base.yml 2>/dev/null; then
+            yq -r '.services | to_entries[] | "\(.key)=\(.value.image // "")"' base.yml \
+              | sort > services_main.txt
+          else
+            touch services_main.txt
+          fi
 
           echo "Comparing images between base and head..."
           : > service_changes.txt
@@ -75,12 +80,11 @@ jobs:
           echo "Detected service changes:"
           cat service_changes.txt || true
 
-          mod_svcs=$(sort -u service_changes.txt | xargs)
-          if [ -z "$mod_svcs" ]; then
-            echo "docker_svc_list=" >> "$GITHUB_OUTPUT"
-          else
-            echo "docker_svc_list=$mod_svcs" >> "$GITHUB_OUTPUT"
-          fi
+          # Flatten into a single space-separated string
+          mod_svcs=$(sort -u service_changes.txt | xargs echo -n)
+
+          # Export for downstream steps (safe single-line)
+          echo "docker_svc_list=$mod_svcs" >> "$GITHUB_OUTPUT"
 
       - name: List of Services for (Re)Deployment
         run: |