pub const ROOT_QUEUE: usize = 2;Expand description
Subtree roots each slice may have waiting in the cert unit’s root queue.
The queue is two deep per slice. Before this credit existed, a slice
offered roots as fast as it made keys (up to 8 batches ahead), so while
the Ed25519 core was still loading its key a third root met a full queue,
was dropped and set the sticky fault. The first card run stopped at 6 of
8 batches that way (2026-10-14). Slices now wait for credit
(CertOutput::roots_popped).