Discussion: optional Y-axis range padding (control plot fill without scaling data)

[itsdiay]

Context

Per CONTRIBUTING, new props need to earn their place — opening this as a discussion before any PR.

Today computeRange hard-codes vertical margin:

const marginFactor = exaggerate ? 0.01 : 0.12

Consumers who want more breathing room (e.g. keep series min/max around the middle 50% of the plot so there is room for growth/decline) currently have to scale or fabricate domain in app code.

Proposal (for discussion)

An optional prop such as rangePadding?: number (fraction of data span added on each side; default stays 0.12 when unset) so apps can choose TradingView-like tight fill vs mid-plot padding without changing their data.

Example: rangePadding={0.5} → data occupies roughly the middle half of the Y-axis (min ≈ 25%, max ≈ 75%).

Why it might earn a prop

• Common charting need (auto-scale fill factor).
• Small API surface: one number, default preserves current behavior.
• Avoids each consumer reinventing Y padding.

Why it might not

• API surface is intentionally small.
• Opinionated defaults over flexibility.
• Apps can already pre-scale values (with tradeoffs for axis labels / formatters).

Happy to adjust or drop this if you’d rather keep padding fixed.