Registry Safety Guidelines

Critical Rules

1. •Never delete without confirmation - always show a confirmation dialog before DeleteSubKeyTree
2. •ShellEx warnings - when deleting shellex entries, warn that third-party app functionality may break
3. •Backup before bulk changes - export to .reg before batch operations
4. •Use writable:true explicitly - OpenSubKey(path, writable: true) - never assume write access
5. •Catch and handle SecurityException - HKCR writes require admin; gracefully handle permission denied

Registry Paths

Enable/Disable Patterns

• •Shell items: set LegacyDisable (REG_SZ, empty) to disable; delete value to enable
• •ShellEx items: rename key with - prefix to disable (e.g., MyHandler -> -MyHandler); preserve default value (CLSID) during rename

Win11 Classic Menu

• •CLSID: {86ca1aa0-34aa-4e8b-a509-50c905bae2a2}
• •Force classic: create HKCU\Software\Classes\CLSID\{...}\InprocServer32 with empty default value
• •Revert: delete the CLSID subtree under HKCU
• •Requires Explorer restart to take effect

Safe Coding Patterns

// Always use 'using' for registry keys
using var key = Registry.ClassesRoot.OpenSubKey(path, writable: true);
if (key == null) return; // guard against missing keys

// Delete values safely
key.DeleteValue("ValueName", throwOnMissingValue: false);

// Delete subkeys safely
parentKey.DeleteSubKeyTree(keyName, throwOnMissingSubKey: false);

For detailed registry path reference, see references/registry-paths.md.