[bar-drilldown] Column Chart with Hierarchical Drilling

[MarkusNeusinger]

Description

A column chart with hierarchical drilling capability, allowing users to click columns to explore nested data categories.

Applications

• Time-based drill (year → quarter → month)
• Geographic drill (region → country → city)
• Product hierarchy exploration
• Financial statement breakdown

Data

• level1, level2, level3 (string) - Hierarchy levels
• value (numeric) - Data values
• Hierarchy: 2-3 levels deep

Notes

• Click column to drill into sub-level
• Breadcrumb trail for navigation
• Animated transitions between levels
• Consistent color mapping
• Back button or click-away to drill up

[claude]

✅ Spec ID: bar-drilldown

Rationale: Column/bar charts with drill-down navigation into hierarchical data levels. Follows existing pie-drilldown naming pattern. Similar to pie-drilldown but uses bar/column visualization instead of pie slices, which is better for comparing values across categories.

[MarkusNeusinger]

Duplicate of #3773. The spec bar-drilldown has been linked to the original issue.