Trigger Guards

A guard is checked once when that trigger is fired internally. If it fails, the engine returns before evaluating any matching rule conditions or actions.

{
  "triggerGuards": [
    {
      "trigger": "PLAYER_JOINED",
      "conditions": [
        {
          "type": "LEVEL_AT_LEAST",
          "params": {
            "level": 5
          }
        }
      ]
    }
  ],
  "rules": [
    {
      "trigger": "PLAYER_JOINED",
      "conditions": [
        {
          "type": "HAS_PERMISSION",
          "params": {
            "permission": "vip"
          }
        }
      ],
      "actions": [
        {
          "type": "GIVE_COINS",
          "params": {
            "amount": 25
          }
        }
      ]
    }
  ]
}

The guard conditions use the same condition shape as rules: static conditions, expression conditions, operators, ref, and !ref.

When To Use

• use a guard for trigger-wide preconditions
• use rule conditions for rule-specific matching
• use action when guards for action-specific checks

Do not use a trigger guard to hide unrelated business rules. It should answer whether the trigger should continue at all.