OptionalpollIntervalMs?: numberThe first poll interval while waiting; it doubles to 2 s.
OptionalwaitTimeoutMs?: numberHow long a caller waits on another process's login. Defaults to 150 s, the lock's lifetime.
Run fn with a live session, logging in and re-running it once when FIB
says the session expired. fn must be re-runnable: every call behind it is
a read.
The one FIB online-banking session every process shares, through Valkey.
A login may revoke the session before it, so logins are single-flight across processes: one holder of a Valkey lock logs in while the rest wait for its session, and a caller whose session died logs in only if the stored session is still the one that died. Each login sends the device token the last one ended with, so every process presents the one browser FIB has seen.