diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index fe6ae14..c71e69d 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -419,11 +419,13 @@ jobs:
 
       - name: Validate backend (imports and app instantiation)
         run: |
-          # Install Python and pip
-          apt-get update && apt-get install -y python3 python3-pip python3-venv
+          # Install Python 3.12 (required for modern type hints like str | None)
+          apt-get update && apt-get install -y software-properties-common
+          add-apt-repository -y ppa:deadsnakes/ppa
+          apt-get update && apt-get install -y python3.12 python3.12-venv python3.12-dev
           
-          # Create virtual environment
-          python3 -m venv /tmp/backend-venv
+          # Create virtual environment with Python 3.12
+          python3.12 -m venv /tmp/backend-venv
           
           # Use venv's pip and python directly (avoids shell activation issues)
           # Install core dependencies including numpy and pillow (needed for module-level imports)