battery-chart

name	battery-chart
description	Builds and renders battery history charts in SwiftUI using Swift Charts. Use when implementing rolling history storage, sampling cadence, and trend visualization for battery percentage.

Battery Chart Skill

Goal

Render a stable, readable charge trend graph.

Steps

1. Append sampled snapshots into a rolling history window.
2. Keep history bounded by age and sample count.
3. Plot percentage over time with Swift Charts.
4. Surface the selected time range (for example, last 6 hours).
5. Handle sparse data gracefully (empty and low-sample states).

Validation Checklist

• No crashes with empty history.
• Graph updates after each refresh tick.
• Percent axis stays in expected range (0-100).