ONH / ONL Auto Levels

This script automatically detects and plots the Overnight High (ONH) and Overnight Low (ONL) for each trading day.
It scans the entire overnight/Globex session (default: 18:00–09:30 EST for ES futures) and records the highest and lowest prices formed during that period.

At the start of the regular trading session (RTH), ONH and ONL levels remain on the chart as key liquidity zones.
These levels are commonly used for:
• Identifying liquidity sweeps
• Opening drive reversals
• Break-and-retest setups
• VWAP + ON levels confluence
• Scalping on 1m–5m charts

The script updates automatically every day and draws clean, minimal levels suitable for intraday traders.
Time settings can be adjusted to match any market or instrument.