Audio Connectables are an internal entity used by the codebase to represent the inputs and outputs of a particular node in the [patch-network].
The code defining the interface for AudioConnectables can be found here: https://github.com/Ameobea/web-synth/blob/1d1f63a8423ab8dd65f110a708525384c9f1f328/src/patchNetwork/patchNetwork.ts#L21