# 046 — Squash bars/legend entries when a chart has too many series

## Summary

`webapp/src/components/PanelChart.tsx` renders one bar (BarChart, lines
103-119) or slice (PieChart, lines 122-145) per `PromqlSeries`, labeled via
`seriesLabel()` (lines 18-23) and colored by cycling through a fixed
8-color palette `COLORS` (line 26). There is no "top N + other" grouping,
bar-squashing, or legend simplification anywhere in this file — with many
series/labels, both charts render an unbounded number of bars/legend rows
and repeat colors once the palette wraps.

## Scope

- Define a threshold above which a panel's series count is considered
  "too many" (bars and legend entries alike).
- Above the threshold, squash extra bars into an aggregated "other"
  bucket (or equivalent visual simplification) rather than rendering one
  bar per series.
- Above the threshold, simplify the legend similarly (e.g. collapse to
  top-N + "other", or a compact/paginated legend) instead of listing every
  series.
- Apply the same treatment consistently across all chart types in
  `PanelChart.tsx` that can have many series (bar, pie), not just one.

## Acceptance criteria

- A panel with a large number of series (seeded fixture) renders a
  bounded number of bars/legend entries instead of one per series, with
  an "other"/aggregate representation for the rest.
- A panel with few series is visually unchanged from current behavior.
- Color assignment no longer visibly repeats for panels within the
  squashed range (i.e. squashing keeps the rendered series count within
  the palette size, or palette collisions are otherwise addressed).

## Depends on

None.