What a login answer teaches the session: the one function every login path
(the Bloks login, the native login and its two-factor step, the recovery nonce
login, the one-tap app login) calls with the answer's logged_in_user. A
login is a new account's facts, so an answer with no fbid_v2 clears the
previous account's id instead of leaving it. With adoptLaunchFbidV2
these are the only writers of MobileSessionState.fbidV2 (a source scan test
fails on any other assignment).
What a login answer teaches the session: the one function every login path (the Bloks login, the native login and its two-factor step, the recovery nonce login, the one-tap app login) calls with the answer's
logged_in_user. A login is a new account's facts, so an answer with nofbid_v2clears the previous account's id instead of leaving it. With adoptLaunchFbidV2 these are the only writers ofMobileSessionState.fbidV2(a source scan test fails on any other assignment).