stat

type Name string

type Options struct {
	Bins      int     // number of bins (histogram/bin stat); 0 = auto
	BinMethod string  // binning strategy: "sturges" (default), "scott", "fd", "sqrt"
	Method    string  // smoothing method: "lm", "loess"
	Points    int     // number of output grid points
	Bandwidth float64 // KDE bandwidth; 0 = Silverman auto-select
	Whisker   string  // boxplot whisker rule: "tukey" (default 1.5×IQR), "range" (min-max)
	Notch     bool    // boxplot: compute notch confidence interval around median
}

type Stat interface {
	// Name returns the stat's typed identifier.
	Name() Name

	// RequiredAes returns the aesthetic channels this stat needs.
	RequiredAes() []string

	// OutputSchema returns the column names this stat produces.
	OutputSchema() []string

	// OutputMapping returns the aesthetic-to-column mapping for the stat's
	// output. The renderer uses this to know which output column maps to
	// which aesthetic channel (e.g., {"x": "x", "y": "count"} for stat_bin).
	// Returns nil for identity stats (no rewriting needed).
	// This replaces hardcoded per-stat switches in the rendering pipeline.
	OutputMapping() map[string]string

	// Compute performs the transformation.
	Compute(ctx context.Context, ds dataset.Dataset, mapping map[string]string, opts Options) (dataset.Dataset, error)
}