At least some embodiments described herein relate to computer-assisted conversation. The set of available conversation segments is updated by addressing conversation segments at the granularity of a conversation segment or a group of conversation segments. For instance, an entire class of conversation segments may be addressed to add, delete, turn on, or turn off, the class of conversation segments. Groups of class of conversation segments may also be similarly addressed. Thus, as the scope of a conversation changes, the available set of conversation segments may likewise change with fine-grained control. Accordingly, rather than pre-plan every set of possible conversations, the context and direction of the conversation may be evaluated by code to thereby determine what new sets of conversation segments should be added, deleted, turned on, or turned off. New conversation segments may even be generated dynamically, taking into account the values of parameters that then exist.