diff --git a/engine.py b/engine.py
new file mode 100644
index 0000000..f172290
--- /dev/null
+++ b/engine.py
@@ -0,0 +1,90 @@
+import os
+import shutil
+from PIL import Image
+from io import BytesIO
+
+class SorterEngine:
+    @staticmethod
+    def get_images(path):
+        """Returns list of image files in a directory."""
+        exts = ('.jpg', '.jpeg', '.png', '.webp', '.bmp', '.tiff')
+        if not path or not os.path.exists(path): return []
+        return sorted([f for f in os.listdir(path) if f.lower().endswith(exts)])
+
+    @staticmethod
+    def get_id_mapping(path):
+        """Maps idXXX prefixes to full filenames for Tab 1."""
+        mapping = {}
+        for f in SorterEngine.get_images(path):
+            if f.startswith("id") and "_" in f:
+                prefix = f.split('_')[0]
+                mapping[prefix] = f
+        return mapping
+
+    @staticmethod
+    def get_max_id_number(folder_path):
+        """Finds the highest idXXX_ prefix in a folder to calculate the next ID."""
+        max_id = 0
+        if not folder_path or not os.path.exists(folder_path):
+            return 0
+        for f in os.listdir(folder_path):
+            if f.startswith("id") and "_" in f:
+                try:
+                    num_part = f[2:].split('_')[0]
+                    num = int(num_part)
+                    if num > max_id: max_id = num
+                except (ValueError, IndexError):
+                    continue
+        return max_id
+
+    @staticmethod
+    def compress_for_web(path, quality):
+        """Reduces image size for browser display to save bandwidth."""
+        try:
+            with Image.open(path) as img:
+                buf = BytesIO()
+                img.convert("RGB").save(buf, format="JPEG", quality=quality)
+                return buf
+        except Exception:
+            return None
+
+    @staticmethod
+    def execute_move(t_path, c_path, t_folder, c_folder, prefix, mode="standard"):
+        """
+        Moves/Renames files based on the script's logic:
+        - standard: selected_target / selected_control
+        - solo: selected_target_solo_woman / control_selected_solo_woman
+        """
+        t_fname = f"{prefix}{os.path.basename(t_path)}"
+        c_fname = f"{prefix}{os.path.basename(c_path)}"
+        
+        subdirs = {
+            "standard": ("selected_target", "selected_control"),
+            "solo": ("selected_target_solo_woman", "control_selected_solo_woman")
+        }
+        
+        t_sub, c_sub = subdirs[mode]
+        t_dst = os.path.join(t_folder, t_sub, t_fname)
+        c_dst = os.path.join(c_folder, c_sub, c_fname)
+        
+        os.makedirs(os.path.dirname(t_dst), exist_ok=True)
+        os.makedirs(os.path.dirname(c_dst), exist_ok=True)
+        
+        shutil.move(t_path, t_dst)
+        shutil.copy2(c_path, c_dst) # Copy control as per script logic
+        
+        return t_dst, c_dst
+
+    @staticmethod
+    def revert_action(action):
+        """Reverses the last recorded action from the history stack."""
+        if action['type'] in ['link_standard', 'link_solo']:
+            if os.path.exists(action['t_dst']):
+                shutil.move(action['t_dst'], action['t_src'])
+            if os.path.exists(action['c_dst']):
+                os.remove(action['c_dst'])
+        elif action['type'] == 'unused':
+            if os.path.exists(action['t_dst']):
+                shutil.move(action['t_dst'], action['t_src'])
+            if os.path.exists(action['c_dst']):
+                shutil.move(action['c_dst'], action['c_src'])
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