Constant MAX_COALESCE_WAIT_MS 

pub const MAX_COALESCE_WAIT_MS: u64 = 60_000;

Upper bound for cache.coalescing.wait_ms (DW-038): 60 s. A follower parked longer than a minute is a stuck request from the client’s point of view; the route’s own timeouts bound the leader, so a wait beyond them only delays the inevitable fail-open.