Slider/rotate drag trajectory claims more drag-time than the whole server-observed solve — synthesized
bh.arena_trajectory_forged · convicts
What it catches
Kitsune arena challenge-solve coherence (slider + rotate gates): the GeeTest-style slider (arena/slider.go) and Arkose-style rotate (arena/rotate.go) verify the drag/rotation TRAJECTORY — MinPts + 'drag too fast' + a velocity coefficient-of-variation floor (the uniform_velocity discriminator). But those checks read the CLIENT-SUPPLIED trajectory t-values, which a headless solver (evaders/arena-solver) PADS: it synthesizes a plausible variable-velocity smoothstep+jitter drag that clears the CV bar, then submits it near-instantly. The SERVER-OBSERVED solve time (issue->verify, tracked in the captchaStore since the OCR-timing rung) cannot be faked. A trajectory whose CLAIMED duration (last_t - first_t) exceeds the whole solve window by >150ms is IMPOSSIBLE — the drag happens WITHIN that window — so the gate emits anomaly:trajectory_exceeds_solve_time, and the detector's /arena/slider/verify AND /arena/rotate/verify relays join it to ks_sid (bh.arena_captcha_superhuman sibling; the shared _join_arena_anomaly map). FP-SAFE BY CONSTRUCTION: a real drag's duration is always <= the server-observed elapsed (network RTT only inflates the server side), so a slow/careful human is never flagged — precision 1.0 is load-bearing. This is the solve-vs-CLAIM analog of the CAPTCHA solve-vs-human-floor tell, and it defeats trajectory synthesis by measuring the one thing the client cannot forge: WHEN the gate issued the challenge. GROUNDED LIVE 2026-07-03: an instant submit with a 2000ms padded slider trajectory trips the anomaly and the joined session convicts, and the rotate gate mirrors it; the SAME trajectory with a real 2.5s wait is silent. Convicting (w0.85). See docs/research-radar.md (arena-solve loop rungs 5-7).
Signals it reads
behavioral.arena_trajectory_forged
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.