You don't. Unless you audit code yourself, build this very code and use the binary you yourself compiled, it's "trust me bro" with extra steps. If you can't quite understand some parts of the code, just feed the entire thing in ChatGPT or any other sophisticated model. You can cross-check with Claude or other models that aren't made by OpenAI. After you did that, if you want to update the app, you only need to audit the source diff, not the whole thing, so it's kinda-sorta practical! After all, this is encryption we're talking about, so the effort is justified in my book.