Constant COUNTER_PAGE0 

pub const COUNTER_PAGE0: u32 = _; // 966_656u32

Device-node frame-counter journal (device-node plan increment 4): the persisted TX reservation boundary for the device identity and RX replay boundaries for its peers, batch-written as one counter_map payload per flush. Separate journal because its write cadence (every COUNTER_PERSIST_BLOCK_SIZE secured frames) must never rotate a snapshot or the identity record away.