Module backoff 

Exponential backoff with jitter, and the “has this retry window run out” check that goes with it. Shared by every worker that reschedules a failed row instead of giving up on it outright.

Functions

exponential_backoff_secs

base_secs * 2^attempt, capped at max_secs. attempt is clamped to keep the shift in range of i64.

next_attempt_at

now + delay_secs, plus a uniformly random 0..=jitter_max_secs so a batch that failed together does not all come back at once.

window_expired

Whether max_age_secs have passed since reference. None (never failed) is never expired.