Which way of installing Claude Code keeps itself up to date without you doing anything?

The principle — how you installed it decides whether staying current is your job.

Why the key is correct — Anthropic states that native installations automatically update in the background to keep you on the latest version. Nothing has to be configured for that to happen.

Why the others are wrong — update behaviour is not universal across routes. It is not a toggle you enable later either, because the native route already does it. And Homebrew installations are documented as not auto-updating, so an available upgrade is not an applied one.

Remember this — if you did not install natively, put the upgrade command somewhere you will actually run it.

Sources — Anthropic's Claude Code overview.