Shell-game answered correctly before the shuffle could finish — swap payload precomputed, not watched
bh.arena_shell_precomputed · convicts
What it catches
Kitsune arena SHELL-GAME solve coherence — a track-under-OCCLUSION gate (arena/shellgame.go), the object-permanence sibling of the arena timing tells. A ball hidden under one of N cups is shuffled by a server-defined swap sequence; the client must WATCH the occluded ball and click its final cup. The SERVER-OBSERVED solve time (issue->verify, tracked in the shell store — unforgeable) is measured against the shuffle runtime (sum of the per-swap animation ms, minted WITH the challenge). A human cannot know the final cup until the shuffle animation SETTLES, so a correct answer necessarily arrives at or after shuffleMs; an automation that reads the swap payload COMPUTES the final position and submits in milliseconds — a correct answer FASTER than the shuffle runtime is precomputed, not watched. The gate returns anomaly:solved_before_shuffle; the detector relay (/arena/shell/verify) joins it to ks_sid so a solver that PASSES the gate is CONVICTED on coherence (the arena thesis: the solve-BEHAVIOUR discriminates, not the puzzle). Targets the snapshot->reason->act agent specifically: sampling the DOM at discrete times cannot follow a ball INVISIBLE during the shuffle, so the agent guesses wrong or reads the payload and answers too fast. HUMAN-TIME-bound (watch the shuffle), NOT compute-bound, so HARDWARE-INDEPENDENT. FP-SAFE BY CONSTRUCTION: the floor is the exact animation runtime the client was given, and no human can answer before the ball settles -> precision 1.0 is load-bearing. GROUNDED LIVE 2026-07-09 BOTH DIRECTIONS: an automation replaying the swaps submits in 1ms -> anomaly + the joined session convicts; a human who waits the 2100ms shuffle then clicks is silent. Convicting (w0.85). See docs/research-radar.md (novel-arena-gates loop).
Signals it reads
behavioral.arena_shell_precomputed
How it fires
present
Bypassed by 10
Frontier evaders that reach the detector uncaught (scored only suspicious, defeating every convicting tell) — this check is not one that stops them. The red-team frontier this detection still has to convict.