https://www.rik-kisnah.ai/tags/redis/Recent content in Redis on Rik Kisnah - BlogHugoenTue, 16 Jun 2026 09:00:00 -0700https://www.rik-kisnah.ai/teach/systems/design-a-token-usage-and-limits-service/Tue, 16 Jun 2026 09:00:00 -0700https://www.rik-kisnah.ai/teach/systems/design-a-token-usage-and-limits-service/Every request to a language model burns tokens. Somebody has to answer ‘may this user spend more?’ in a few milliseconds, for personal accounts and for companies with a hundred engineers under one bill, and then record what was actually spent. Design that gate: the entities, the three endpoints, the counters, and the one rule that keeps it from ever blocking the model by accident.https://www.rik-kisnah.ai/teach/systems/design-a-one-to-one-chat/Tue, 21 Apr 2026 09:00:00 -0700https://www.rik-kisnah.ai/teach/systems/design-a-one-to-one-chat/One-to-one, text only, web only. That is all the interviewer gives you. Ask for the rest, then design the gateway that finds the recipient, the inbox that survives them being offline, the presence key that expires on its own, and defend Redis Pub/Sub against Kafka out loud.