Rules Engine

Rules let you apply style changes to groups of cards based on entity state — without touching each card individually. A single rule can update dozens of cards at once.

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Concept

A rule watches one or more entities. When a condition matches, it pushes a style patch to all targeted cards. When the condition no longer matches, the patch is removed.

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Where Rules Live

Rules are defined in content packs or directly in the LCARdS config helper. You manage them from the Rules tab in any card editor, or through the Config Panel.

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Rule Structure

rules:
  - id: my-rule
    name: Nav highlight on motion
    priority: 10
    conditions:
      - entity: binary_sensor.motion_hallway
        state: "on"
    targets:
      tags: [nav]           # All cards with this tag
      ids: [header-card]    # Specific card IDs
      types: [button]       # All cards of a type
    style:
      border:
        color: "{theme:colors.ui.primary}"
      card:
        color:
          background: "#1a1a2e"

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Conditions

Field	Description
entity	Entity ID to watch
state	Match exact state string (e.g. "on", "home")
above	Numeric state greater than or equal to value
below	Numeric state less than value
attribute	Watch an attribute instead of state
template	Jinja2 expression — rule fires when it returns true

Multiple conditions in the same rule are ANDed together. Use multiple rules for OR logic.

conditions:
  - entity: binary_sensor.door
    state: "on"
  - entity: input_boolean.night_mode
    state: "on"

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Targets

Field	Description
tags	List of tags — targets all cards with any of these tags
ids	List of specific card IDs
types	Card types: button, slider, elbow, chart, data-grid, msd

Targets are combined: a card matching any target receives the patch.

Tagging Cards

Add tags to any card in its config:

type: custom:lcards-button
tags: [nav, main-panel]

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Style Patches

The style block in a rule follows the same structure as card-level style. Only the specified properties are overridden — other styles are untouched.

style:
  border:
    color: "#FF0000"
    width: 3
  card:
    color:
      background:
        default: "#200000"
        active: "#3a0000"

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Priority

When multiple rules target the same card, higher priority values win. Default priority is 0.

rules:
  - id: base-style
    priority: 0
    ...
  - id: alert-override
    priority: 100   # This wins when active
    ...

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Viewing Active Rules

In any card editor, the Rules tab shows:

• All rules currently in the system
• Which rules are currently active (condition matched)
• Which patches are being applied to this card

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