nx_ivvguard.nx

nx_ivvguard.nx -- the PURE safety predicates of the IV+V beat, extracted so they can be PROVEN BEFORE any code that forks or deletes is written (2026-08-07). WHY THIS FILE EXISTS SEPARATELY. nx_ivv_beat.cron.sh is the only remaining clock wrapper that FORKS A BINARY NAMED IN A DATA PLANE and DELETES FILES BY PREFIX GLOB. Two shell case-patterns are the only things that make it safe to run at all: the exe must match dot-slash-nx-underscore-star-dot-elf or dot-slash-underscore-star-dot-elf, and the pre-wipe path must begin with slash-tmp-slash. (STAR)WHEN A BEAT TAKES ITS COMMANDS FROM DATA, THE ALLOWLIST IS NOT A FEATURE OF THE BEAT -- IT IS THE ONLY THING THAT MAKES THE BEAT SAFE TO RUN AT ALL. A subtle mis-anchor turns a monitoring beat into an execution primitive, and a wrong prefix test deletes by glob outside the temp directory. So the predicates ship FIRST, as pure functions over fabricated strings, gated with NEGATIVE cases that must REFUSE -- exactly the shape that let clk_edf_pick_free be proven before it was ever wired to a live dispatcher. license_tier: ORIGINAL No hw writes (Rule 26). Pure: no side effects.