Prompt Engineering

Mid-Conversation System Message

Adding a new instruction partway through a chat without rewriting the original setup, so cached savings stay intact.

Definition

A system-role message appended to the messages array to add operator instructions partway through a conversation without editing the top-level system prompt, which keeps the cached prefix intact.

Example

Mid-session, append {role: "system", content: "The user is now on the free plan."} instead of editing the top-level system prompt.