Cache reliability is a pricing term: What I learned measuring DeepSeek-V4.1-Flash on DigitalOcean's serverless inference

GDeepSeek-V4.1-Flash has the lowest cache-read price on DigitalOcean Serverless Inference. Across 844 API calls, its cache missed on one warm turn in five, so a 15-turn agent session cost 2.2× more than on GLM-5.3-Flash. We measured it all and show why cache reliability, not cache price, decides your inference bill.