Optional ReadonlydescriptorPer-consumer annotations. registrations holds memory registrations
keyed by the registrar's id (e.g. "fabric:verbs;mlx5_0").
ReadonlydomainThe memory domain, i.e. who can dereference ptr: "host" (the default)
means any CPU code in the process; a device domain such as "cuda:0"
means only that device's code. Memory registration (e.g. RDMA) is not a
domain - see descriptor.registrations.
ReadonlykindReadonlylengthReadonlyptr
A payload that lives in memory owned outside the JS heap (e.g. a Rust-allocated buffer).
release()must be called once nothing needs the buffer - ownership/lifetime is explicit rather than GC'd, since JS code cannot safely retain a raw pointer past the point its owner frees it.