Pramod KalipatnapuCofounderRevefi
Engineering team. Raden data agent serving enterprise customers.
Revefi blog, published Read the write-up (opens Revefi blog in a new tab)
Observation
At Revefi, one timestamp at the top of the prompt was enough to break caching for an agent.
- Takeaway
- Order every prompt from stable to volatile, and alert on cache hit rate per agent, because a broken cache fails silently and shows up only on the bill.
- What happened
- An upgrade added user context and a per-call timestamp near the top of Raden's system prompt. Revefi then saw its agent spend climb and its cache hit rate collapse, since nothing after the timestamp could be read from the cache. Kalipatnapu and Istasis Mishra moved volatile content to the end of the prompt. Cache reads rose to 99% of input tokens the week the fix shipped, and the post reports a 90% cut in the agent's spend.
“Earlier this year, we had to quickly reduce our data spend. We had inadvertently introduced a change that made our costs spiral out of control!”
- Public engineering write-up
- Spend and cache metrics reported
Deployment details
Engineering team. Raden data agent serving enterprise customers.
- Public engineering write-up
- Spend and cache metrics reported
- Team
- Revefi engineering
- Workload
- Long-running data agent, dozens of model turns per request
- Product version
- Claude API prompt caching, LangChain middleware
- Measurement
- Cache reads as a share of input tokens in the Anthropic Console; agent spend





