System Prompt vs User Prompt

Separate policy from work The system prompt defines recurring behavior. The user prompt supplies the current job. Mixing both makes templates harder to reuse and increases the chance that temporary context changes permanent rules.

System layer Use it for role, audience, safety limits, source policy, tools, and required response conventions. Keep it concise enough to audit.

User layer Use it for the objective, input data, variables, examples, deadlines, and the exact deliverable. Delimit long source material clearly.

Test the boundary Change only the user task across several cases. If the assistant’s stable behavior drifts, move the relevant rule to the system layer or enforce it in code.