1. A computer system configured to improve security of client computers interacting with server computers through an intermediary computer, and comprising: one or more processors; one or more non-transitory storage media storing instructions which, when executed by the one or more processors, cause: receiving a first set of instructions from a server computer; sending, to a remote client computer, the first set of instructions and a second set of instructions that define one or more supervisor operations, which when executed by a runtime environment on the remote client computer, cause the runtime environment to: generate one or more objects in a memory on the remote client computer; intercept a call to a particular object of the one or more objects in the memory on the remote client computer; send a set of telemetry data to a server computer indicating the particular object was referenced.