Each app installs a blank file and points ShellNew at it. Explorer
lists a type only through its default class, so a type no program
handles (no default, or one naming no class) gets the app's class;
an installed handler is never replaced. Uninstall removes only what
this install wrote.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>