XeroAntiCheat

Lightweight, accurate anti-cheat for Paper 1.21.x

Latest Updates (v1.1.1)

CriticalCheck: Removed dead code — the "no-air crit" detection branch was logically unreachable because isCritical=true requires !isOnGround, making the subsequent isOnGround check always false. The check now only flags "crit while sprinting" (the only branch that could actually fire). Removed allow_jump_crits config key. (Future enhancement: Option B damage-ratio detection.)
InventoryMoveCheck: Replaced Math.sqrt() with squared distance comparison (distanceSquared > 0.01), consistent with the ReachCheck optimisation.

ReachCheck: Now measures distance to entity bounding box center instead of feet. Eliminates false negatives when attacking tall entities (horses, iron golems, withers). Also switched from distance() to distanceSquared() comparison, removing a Math.sqrt() from the hot path.
AutoClickerCheck: checkPattern() rewritten with zero-allocation two-pass iterator approach. Previously allocated two ArrayList objects on every combat click.
TimerCheck: Removed redundant blink detection from check() method. Blink detection is fully handled by the 5-tick scheduled task. setLastMovePacketTime() retained to feed the task.
KillAuraCheck: Removed unused EntityEffect import.