Style Defaults

The style: block on a layer provides optional visual defaults: palette, opacity, color ramp, and info panel overrides. It does not declare capabilities, queryability, chart configuration, or interactions. Those concerns belong elsewhere.

Decided in ADR-0015 D2 - "views: becomes style:. Optional visual defaults only."

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Schema

Field	Type	Required	Description
palette	string	No	Named color palette (e.g., viridis, terrain, rdbu, avalanche).
opacity	number	No	Layer opacity, 0.0 to 1.0. Default: 1.0.
colorRamp	list	No	Explicit color stops. Alternative to a named palette. Each entry: { value, color }.
rescale	string	No	Value range for palette mapping, as "min,max" (e.g., "0,60").
info	object	No	Info panel configuration. Overrides auto-derived fields.
table	object	No	Table rendering hints.
form	object	No	Interactive parameter control definitions.

info Block

Field	Type	Required	Description
info.fields	list	No	Visible fields. Restricts which fields appear in the info panel.
info.format	string	No	Display template (e.g., "{value}m", "{value}deg").
info.section	string	No	Grouping label in the info panel (e.g., Terrain, Weather).
info.hierarchy	list	No	Nested lookup order for hierarchical data.

table Block

Field	Type	Required	Description
table.columns	list	No	Column definitions. Each entry: { field, label, format, width }.

form Block

Each key in the form block defines a control bound to a compute parameter:

Field	Type	Required	Description
type	enum	Yes	Control type: slider, dropdown, toggle.
label	string	No	Human-readable label.
min	number	For slider	Minimum value.
max	number	For slider	Maximum value.
step	number	No	Step increment for sliders.
default	any	No	Default value.
values	list	For dropdown	Available options.

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What style: Covers

The style: block provides visual defaults that apply wherever the layer appears. These are hints to the renderer, not capability declarations.

Field	Purpose
palette	Named color palette for raster rendering
opacity	Default opacity
colorRamp	Explicit color stops as an alternative to a named palette
rescale	Value range for palette mapping
info	Override auto-derived info panel fields
table	Hints for table column rendering
form	Parameter controls for interactive layers

What style: Does NOT Cover

Concern	Where It Belongs	Why
Chart config (type, axes, marks)	View content: block (Views)	Charts are view-specific layout items
Capabilities (queryable, sampleable)	Inferred from type: + op registry	Never manually declared
Interactions (click, hover, draw)	View-level per-layer config (Interactions)	Behaviors, not visual defaults

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Style Resolution Cascade

When a layer is rendered, its visual styling is resolved through a fallback chain. Most specific wins:

1. View content item style: override - per-view, per-content-item overrides in the workspace views: block.
2. Layer style: block - the layer's own defaults.
3. Operation display_hints: - suggested defaults from the op YAML, if the layer has compute.op:. Decided in ADR-0009.
4. Type-based defaults - fallback for layers with no styling at any level. Raster gets viridis, vector gets blue fill, table gets default grid.

View-level style override (most specific)
    |
    v falls back to
Layer style: block (defaults)
    |
    v falls back to
Op display_hints: (from op YAML)
    |
    v falls back to
Type-based defaults (least specific)

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Examples

Raster with palette and info

layers:
  terrain/elevation:
    uri: catalog://terrain/dem
    type: raster
    style:
      palette: terrain
      rescale: "0,4000"
      info:
        fields: [elevation_m]
        format: "{value}m"
        section: Terrain

Custom color ramp

layers:
  terrain/slope:
    uri: catalog://terrain/slope/wasatch@v2
    type: raster
    style:
      palette: avalanche
      opacity: 0.7
      colorRamp:
        - { value: 0, color: "transparent" }
        - { value: 30, color: "yellow" }
        - { value: 45, color: "red" }
        - { value: 55, color: "purple" }
      info:
        fields: [slope_degrees]
        format: "{value}deg"
        section: Terrain

Form controls for interactive parameters

layers:
  pricing/calculator:
    type: computed
    compute:
      engine: sql
      query: |
        SELECT :count * ondemand_hr * :hours AS monthly_cost
        FROM :prices WHERE instance_type = :instance_type
      inputs:
        prices: { layer: cloud_pricing/ec2 }
      params:
        instance_type: m5.xlarge
        hours: 730
        count: 1
    style:
      form:
        instance_type:
          type: dropdown
          label: Instance Type
          values: [m5.large, m5.xlarge, m5.2xlarge, c5.xlarge]
        hours:
          type: slider
          label: Hours/Month
          min: 0
          max: 730
          step: 10
          default: 730
        count:
          type: slider
          label: Instance Count
          min: 1
          max: 100
          default: 1
      table:
        columns:
          - { field: instance_type, label: "Instance", width: 200 }
          - { field: monthly_cost, label: "Monthly Cost", format: "${value}" }

Layer with no style block

layers:
  hydrology/drainage:
    uri: catalog://hydrology/nhd
    type: vector
    # No style: block needed.
    # Type "vector" uses default blue fill.
    # Info fields auto-derived from attribute table.

Info override on a computed layer

layers:
  astro/sun_moon:
    type: computed
    compute:
      engine: python
      module: ./sun_moon.py
      function: compute
    style:
      info:
        fields: [sunrise, sunset, moon_phase, moon_illumination]
        section: Sun & Moon
    # Not rendered on map - no palette/opacity needed.