Island-Dev-Crew Fail open island
A breach turned into "nothing was checked" by nothing more than a dead pipe (C4). A caller who treats an infrastructure answer as "retry later" and a verdict as "report it" hears about the breach never. Exit 3 is real and documented here for a separate empty-input path, so an island-wide declaration allowlist still passes the broken command. The rule has to bind each probe to that command's documented code: expected 1 may stay 1 or seal an IO fault as 2, never borrow the empty-input command's 3.
enforced: closed-stream-check.py reports the ordinary scan leaking when stdout is closed, while accepting the real empty-input command at its documented exit 3 with either stream closed.advisory: nothing else here is real.
python3 scripts/scan-gate.py # exit 1
python3 scripts/scan-gate.py --empty # exit 3