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Why Appending to Your Agent's System Prompt Breaks Prompt Caching

Why Appending to Your Agent's System Prompt Breaks Prompt Caching

Appending a timestamp or status line to an agent's system prompt changes the prompt prefix on every turn. Prompt caching matches only a contiguous token range from position zero, so the first changed token ends reuse and everything after it is reprocessed at full price. The post reports a case where a task that should have cost about $21 billed about $200, explains the arithmetic, and shows a cache-stable ordering: static system prompt first, volatile text at the tail. Full write-up: https://hackyjs.com/posts/why-appending-to-your-agents-system-prompt-breaks-prompt-caching

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Chrome 157's LanguageDetector on Android: Test It Without a Backend

Chrome 157's LanguageDetector on Android: Test It Without a Backend

Chrome 157 reportedly ships on-device language detection on Android, and the interesting part isn't the detection call. It's that availability() is the API. This walkthrough covers why `'LanguageDetector' in window` is a false positive, what the four availability states mean, and how a typed capability probe lets callers tell a missing API from a model that still needs a download. Then a backend-free test harness: serve a static page over adb reverse and localhost counts as a secure context. Finally, the fallback ladder that still stays in place, plus the caveats worth flagging, since the release claim comes from secondary coverage and needs checking against the primary release notes. Full write-up: https://hackyjs.com/posts/testing-chrome-157s-languagedetector-api-on-android-without-a-backend

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Hunting Ivanti Connect Secure Zero-Days: From Auth Bypass to Implant, With IoCs and Log Sources

Hunting Ivanti Connect Secure Zero-Days: From Auth Bypass to Implant, With IoCs and Log Sources

Rapid7 is warning about two more Ivanti Connect Secure zero-days under active exploitation. This short walks through the documented pattern from earlier ICS waves: pre-auth access, web shell, implant, then a pivot into identity. It ranks the cheapest triage checks first, shows why paired web-root file changes matter, and explains why patching is not cleanup: verify the build, run the integrity check, rotate secrets and SAML certificates, invalidate active VPN sessions, and if you cannot patch, remove the admin console from internet reachability and forward full logs today. The source does not assign unverified CVE IDs or publish exploitation mechanics for the new bugs. Read the full write-up for the triage queries and log sources: https://hackyjs.com/posts/hunting-ivanti-connect-secure-zero-days-from-auth-bypass-to-implant-with-iocs-and-log-sources

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