155 responses leaked between AI customers: the GLM-5.3 KV cache bug — and the canary test for YOUR provider

On Cloudflare Workers AI, 155 GLM-5.3 responses contained other customers' data — stale KV-cache pages served with HTTP 200. The mechanism, the 25-minute repro, the SGLang bug behind it, and a canary script that tests YOUR provider for cross-request leaks.