Constant FAILURE_RETRY_MS 

pub const FAILURE_RETRY_MS: i64 = _; // 600_000i64

How long a FAILED window stays skipped before the scheduler retries it: without this, a persistent failure (unwritable directory, unusable store) would re-burn a full export attempt on every 30 s tick, forever. Time-based, not attempt-count-based — no schema change.