Prompt - Technical Spike Investigation Plan

I need to run a technical spike. The decision we must make: [OPEN QUESTION]. What we already know: [CONTEXT / SYSTEMS / CONSTRAINTS]. Write a spike plan that: 1) States the decision clearly, 2) Separates what we know from what we must learn, 3) Proposes 2-3 investigation approaches with pros/cons, 4) Specifies the output format (decision doc, prototype, benchmark numbers), 5) Suggests a timebox. Keep it focused so an engineer can start immediately.