Smooth-pursuit tracking held within a few px of the moving target (superhuman tracking accuracy)
bh.arena_pursuit_superhuman · convicts
What it catches
Kitsune arena SMOOTH-PURSUIT TRACKING gate (arena/pursuit.go) — 'keep the cursor on the moving dot for a few seconds' (a continuous-tracking anti-bot check). A dot moves along a deterministic Lissajous path (public — the client renders the dot from it); the client follows with the cursor, reporting samples {t, x, y}. The server recomputes the target position at each sample time and scores the MEAN TRACKING ERROR. NOVEL tell (a NEW behavioural family — continuous tracking accuracy / smooth-pursuit): a human's eye-hand smooth pursuit trails a moving target with tens of px of error (intrinsic visuomotor lag ~100-150ms + jitter — pursuit is NOT pixel-accurate); a bot that computes the public path holds the cursor within a few px of it the whole run. A mean error below pursuitErrorFloor (8px) is superhuman tracking. anomaly:pursuit_superhuman -> the detector relay (/arena/pursuit/verify) joins it to ks_sid so a PASS is CONVICTED on coherence. DISTINCT from the track gate (which catches a snapshot-reason-act LLM agent clicking a stale position) — this measures how ACCURATELY a continuous follow hugs the target, a different tell. FP-SAFE BY CONSTRUCTION: no human tracks a moving target within 8px mean error over seconds (real smooth-pursuit error is tens of px); the gate's pass threshold (55px) admits a genuine human follow while the superhuman floor sits far below it. EXPERIMENTAL (w0.85, calibration: the RED evader that adds ~20px of synthetic jitter to its computed-path follow evades — but must then simulate a realistic human pursuit trace, raising the bar; the greedy path-following bot is caught). GROUNDED LIVE BOTH DIRECTIONS: a bot setting cursor = computed target(t) (mean error ~0) convicts; a human-like jittered follow (~25px mean error) passes silently.
Signals it reads
behavioral.arena_pursuit_superhuman
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.