Press-and-hold gate solved with a static (no-tremor) hold or an impossible claimed hold time
bh.arena_hold_robotic · convicts
What it catches
Kitsune arena PRESS-AND-HOLD gate (arena/presshold.go) — the ubiquitous Cloudflare 'Press & Hold' / DataDome / HUMAN family, reproduced as owned infra (no clone/asset). The client holds ONE button for the shown duration, then releases, reporting its achieved hold + the held-pointer position samples. TWO SERVER-OBSERVED prongs make the solve-BEHAVIOUR discriminate (the arena thesis, not the puzzle): (1) STATIC HOLD — the spatial std (tremor) of the held-pointer samples. A real finger/mouse held down drifts continuously (an irreducible biomechanical jitter floor); a scripted hold that INJECTS samples pins them to one coordinate, collapsing the std to ~0. A tremor below holdTremorFloor (0.5px) WHEN the client reported >= holdMinSamples (4) samples is a robotic hold. (2) IMPOSSIBILITY — the claimed hold vs the SERVER-OBSERVED solve age (issue->verify): a hold longer than the whole round-trip window could contain is fabricated. Either prong -> anomaly:hold_robotic; the detector relay (/arena/presshold/verify) joins it to ks_sid so a PASS is CONVICTED on coherence. The single-button hold-DYNAMICS twin of the multi-target bh.arena_timing_superhuman (release-precision). FP-SAFE BY CONSTRUCTION: a motionless human touch-hold reports too few samples to be judged on tremor (only the impossibility prong applies, which is physics), and a hand that moves enough to emit >= 4 samples always spreads them > 0.5px; the elapsed always covers a real hold. EXPERIMENTAL (w0.85, calibration: the tremor floor is set under human hold-jitter from the reference solver; widen if a very steady high-DPI mouse is seen to dip under it). Test both directions: a static/injected hold (tremor ~ 0) or an instant-but-long-claimed hold convicts; a real drifting hold that spends the time is silent.
Signals it reads
behavioral.arena_hold_robotic
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.