The prefix grows

Each completed turn becomes part of the next request.

Turn 1: [instructions] [question A]
Turn 2: [instructions] [question A] [answer A] [question B]
Turn 3: [instructions] [question A] [answer A] [question B] [answer B] [question C]

Material that was new on one turn can belong to the matching prefix on the next.

The reusable beginning can grow with the conversation.