Agent Guide: arcgis-visualization

Quick-reference for renderers on SDK 5.1. Read before styling a layer.

Quick Decision Tree

1. Uniform? → SimpleRenderer.
2. Categories? → UniqueValueRenderer (field + uniqueValueInfos + defaultSymbol).
3. Numeric ranges? → ClassBreaksRenderer (contiguous classBreakInfos + defaultSymbol).
4. Point density? → HeatmapRenderer, on points only.
5. Continuous value? → visualVariables (color/size) on a SimpleRenderer.

Setup Checklist

• Style a FeatureLayer through layer.renderer; graphic.symbol is ignored there.
• Always set defaultSymbol: values with no class, out of range, or null are otherwise not drawn.
• Match unique values with the exact case of the data ("Park" is not "park").
• Use heatmaps only on point layers: on polygons nothing is drawn and nothing errors.

Anti-patterns (one-liner reminders)

• ❌ Looping to set feature.symbol on FeatureLayer results.
• ❌ A renderer without defaultSymbol over data with gaps or nulls.
• ❌ uniqueValueInfos values in a different case than the data.
• ❌ Heatmap on polygons.

Files in This Skill

• SKILL.md / SKILL.es.md — full guides
• references/api-detail.md — renderer + visualVariable signatures
• references/examples.md — one example per renderer
• references/pitfalls.md — extended troubleshooting
• scripts/snippet-unique-value.ts, snippet-class-breaks.ts, snippet-heatmap.ts, snippet-visual-variables.ts