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securityJune 16, 2026· 5 min read

Negative / anti-hallucination cache (CFLAG): how it works and when to use it

Negative / anti-hallucination cache (CFLAG), records known-bad answers so every paraphrase of the question that would reproduce a hallucination is caught. Here's how Crowkis does it and why it matters for cost and safety.

The cheapest token is the one you never spend twice. Negative / anti-hallucination cache (CFLAG) is how Crowkis records known-bad answers so every paraphrase of the question that would reproduce a hallucination is caught.

In plain words: In plain words: negative / anti-hallucination cache (cflag) records known-bad answers so every paraphrase of the question that would reproduce a hallucination is caught.

How it works

Crowkis records known-bad answers so every paraphrase of the question that would reproduce a hallucination is caught. It runs inside one Redis-compatible engine, so it composes with semantic caching, agent memory, and the other intelligence layers instead of being a separate service you wire together.

crowkis cli
CFLAG "is X free?" "yes forever" REASON "hallucinated"

Why it matters

Repetitive LLM workloads are where the money is, and semantic caching can cut costs up to 60-70% on repetitive workloads. Negative / anti-hallucination cache (CFLAG) is part of what makes that reuse safe rather than reckless, the difference between a cache you trust in production and one you audit after every incident. Drop it in over RESP, gRPC, REST, or MCP, no rewrite required.

Infrastructure earns the critical path one boring, verifiable feature at a time.