Fix #113: Preserve plugins during application updates

Add backup/restore mechanism to prevent plugin loss on update:
- Backs up plugins to temp location before update extraction
- Restores plugins after cleanup completes
- Each plugin preserved as-is (no uninstallation logic needed)
- Temp backups cleaned up automatically after successful restore

updater.py

@@ -494,9 +494,132 @@ def _remove_readonly(func: Callable[[str], Any], path: str, exc: Any) -> None:
     func(path)
 
 
+def _backup_plugins(platform_name: str, app_name: str, source_dir: str, dest_dir: Optional[str] = None) -> bool:
+    """
+    Backs up plugins from source directory to a temporary location.
+    
+    Issue #113: Preserve plugins during updates
+    
+    Returns True if backup was successful, False otherwise.
+    """
+    plugins_src = os.path.join(source_dir, "plugins")
+    
+    if not os.path.exists(plugins_src):
+        print("No plugins directory to backup.")
+        return False
+    
+    # Create a temporary backup location (outside app dir so it won't be wiped)
+    import tempfile
+    backup_temp = tempfile.mkdtemp(prefix=f"{app_name}_plugins_backup_")
+    plugins_dest = os.path.join(backup_temp, "plugins")
+    
+    try:
+        shutil.copytree(plugins_src, plugins_dest)
+        plugin_count = sum(1 for f in os.listdir(plugins_dest))
+        print(f"Backed up {plugin_count} plugin(s) to: {plugins_dest}")
+        
+        # Store backup path in a marker file for restoration
+        marker_path = os.path.join(backup_temp, ".plugins_backup_marker")
+        with open(marker_path, "w") as f:
+            f.write(f"plugins_dir={plugins_dest}\n")
+            f.write(f"target_dir={source_dir}\n")
+        
+        return True
+    except Exception as e:
+        print(f"Failed to backup plugins: {e}")
+        # Cleanup failed backup attempt
+        try:
+            shutil.rmtree(backup_temp, onexc=_remove_readonly)
+        except Exception:
+            pass
+        return False
+
+
+def _restore_plugins(platform_name: str, app_name: str, source_dir: str) -> bool:
+    """
+    Restores plugins from temporary backup to the application directory.
+    
+    Issue #113: Preserve plugins during updates
+    
+    Returns True if restoration was successful, False otherwise.
+    """
+    import tempfile
+    
+    # Find all plugin backup temp directories
+    temp_dir = tempfile.gettempdir()
+    backups_found = []
+    
+    try:
+        for entry in os.listdir(temp_dir):
+            if entry.startswith(f"{app_name}_plugins_backup_"):
+                backup_path = os.path.join(temp_dir, entry)
+                marker_path = os.path.join(backup_path, ".plugins_backup_marker")
+                if os.path.exists(marker_path):
+                    backups_found.append((backup_path, entry))
+    except Exception as e:
+        print(f"Error searching for plugin backups: {e}")
+    
+    if not backups_found:
+        print("No plugin backups found to restore.")
+        return False
+    
+    # Restore from all found backups (in case multiple exist)
+    plugins_restored = 0
+    
+    for backup_path, entry_name in sorted(backups_found):
+        try:
+            marker_path = os.path.join(backup_path, ".plugins_backup_marker")
+            
+            # Parse marker file to get original paths
+            backup_info = {}
+            with open(marker_path, "r") as f:
+                for line in f:
+                    if "=" in line:
+                        key, value = line.strip().split("=", 1)
+                        backup_info[key] = value
+            
+            plugins_src = backup_info.get("plugins_dir", os.path.join(backup_path, "plugins"))
+            
+            # Create plugins directory if it doesn't exist
+            target_plugins_dir = os.path.join(source_dir, "plugins")
+            os.makedirs(target_plugins_dir, exist_ok=True)
+            
+            # Copy each plugin to target
+            if os.path.exists(plugins_src):
+                for item in os.listdir(plugins_src):
+                    src_item = os.path.join(plugins_src, item)
+                    dst_item = os.path.join(target_plugins_dir, item)
+                    
+                    if os.path.isdir(src_item):
+                        if os.path.exists(dst_item):
+                            shutil.rmtree(dst_item, onexc=_remove_readonly)
+                        shutil.copytree(src_item, dst_item)
+                    else:
+                        shutil.copy2(src_item, dst_item)
+                    plugins_restored += 1
+                
+                # Cleanup backup after successful restore
+                try:
+                    shutil.rmtree(backup_path, onexc=_remove_readonly)
+                    print(f"Cleaned up backup directory: {entry_name}")
+                except Exception as e:
+                    print(f"Warning: Could not cleanup backup: {e}")
+        
+        except Exception as e:
+            print(f"Failed to restore plugins from {entry_name}: {e}")
+    
+    if plugins_restored > 0:
+        print(f"Restored {plugins_restored} plugin(s) to: {os.path.join(source_dir, 'plugins')}")
+        return True
+    
+    return False
+
+
 def finish_update_if_needed(platform_name: str, app_name: str, cfg_path: str, finish_update: bool) -> None:
     """
     Completes a pending application update if '--finish-update' is present in the command-line arguments.
+    
+    Issue #113: Added plugin preservation during updates.
     """
 
     if not finish_update:
@@ -504,6 +627,11 @@ def finish_update_if_needed(platform_name: str, app_name: str, cfg_path: str, fi
 
     print("Finishing update...")
 
+    # 0. Backup plugins BEFORE we do anything (Issue #113)
+    target_base = get_app_dir()
+    if os.path.exists(target_base):
+        _backup_plugins(platform_name, app_name, target_base, None)
+
     # 1. Reset welcome dialog config flag
     update_cfg = configparser.ConfigParser()
     try:
@@ -611,6 +739,9 @@ def finish_update_if_needed(platform_name: str, app_name: str, cfg_path: str, fi
                 else:
                     print(f"Failed to delete update folder '{folder}' after 3 attempts: {e}")
 
+    # 6. Restore plugins after update (Issue #113)
+    _restore_plugins(platform_name, app_name, target_base)
+
     if "--finish-update" in sys.argv:
         sys.argv.remove("--finish-update")