Constant SHARED_DATA_CAP_BYTES 

pub const SHARED_DATA_CAP_BYTES: usize = _; // 1_048_576usize

Per-module cap on the VM-scoped shared-data store: total bytes (key + value lengths summed over the entries). The store outlives every request (module lifetime), so an unbounded map is a slow OOM the wasm ResourceLimiter cannot see. A set that would exceed the cap FAILS (the plugin gets an error status it can branch on) — entries are never evicted: a silently evicted rate-limit counter or cache entry is a correctness bug, a refused set is a signal.