Raw broadcast stream of session changes. Prefer onAuthStateChange
for the common callback-with-unsubscribe pattern; this getter
exists for callers building higher-level reactive integrations
(e.g. piping into a Riverpod/Bloc StreamProvider).
Stable per-install anonymous identifier. Async for parity with
the TS / native SDKs where the platform may need to await a
persistence read; today the Dart core keeps it in memory and
returns immediately.
Subscribe to session changes. Fires after every signIn*, signUp*,
refresh, and signOut call. Returns a StreamSubscription — call
.cancel() on it to unsubscribe.
Request a one-time passcode for email. The server emails a
6-digit code; the user types it into the app, then call
verifyEmailOtp to exchange for a session.