Understand the mechanism
Prompt caching reuses repeated context under the service’s rules. It is not simply a shared cache of customer answers. Stable instructions or reference material are candidates; customer-specific messages and changing facts remain request-specific.
Organize stable and changing data
Keep approved service instructions separate from the current case. Version policy changes and test that answers use the updated material. Avoid mixing reusable instructions with one customer’s sensitive records.
Measure actual savings
Compare reuse frequency, total cost and latency. Highly variable conversations may benefit less. Start with a repeated task such as checking product descriptions against a stable style guide and expand based on observed results.