Median inter-keystroke interval below the human cadence floor
bh.keystroke_interval_floor ·
behaviorallayer
behavioralcategory
What it catches
FP-Agent (arXiv 2605.01247, radar G13): LLM browser agents type at 1-5ms inter-key (Browser-Use 5.31ms, Manus 1.39ms) vs humans 100ms+. Orthogonal to bh.keystroke_entropy_floor: agent-speed typing keeps human-like ENTROPY (sub-ms gaps spread across log2 buckets) while its median interval is non-human. EVADES-first GROUNDED 2026-06-24: a Playwright delay:0 fast-type measured entropy 0.766 (ABOVE the 0.15 entropy floor, so it evades that rule) but median inter-key 0.9ms (min 0.6 / max 2.1) — caught here. FP-safe: human median is 100-300ms (even record typists ~60ms), so a median <30ms over >=4 keystrokes is non-human.
Signals it reads
behavioral.keystroke_interval_ms
How it fires
below_threshold (threshold 30.0)