rlmesh_remote_vector_env_num_envs
Env construction connects; Model construction only validates. Remote I/O is exclusive, while immutable accessors/cancellation may overlap any call. Accessor pointers remain borrowed until free, including after close.
uint64_t rlmesh_remote_vector_env_num_envs(
const RLMeshRemoteVectorEnv* remote_vector_env
)