Define what a stopped response means
Begin with one streamed answer and decide what the visitor sees after selecting stop. Agree whether the partial text remains, how its state is explained and which action begins another response. The interface and backend need a shared cancellation rule so late fragments do not unexpectedly change a response already presented as stopped. Review the conversation during a slow connection and after a disconnect. Keep the controls understandable without asking the visitor to know how the underlying stream works.
