Engine API

The engine is the core evaluation service. It accepts a policy rule and data, evaluates the rule, and returns the result.

Endpoint

POST https://api.policy.keloran.dev/run

Request

Field	Type	Required	Description
rule	string	Yes	The policy rule text
data	object	Yes	JSON data to evaluate against

Example Request

curl -X POST https://api.policy.keloran.dev/run \
  -H "Content-Type: application/json" \
  -d '{
    "rule": "A **Person** gets approved if __age__ of **Person** is greater than 18.",
    "data": {
      "Person": { "age": 25 }
    }
  }'

Response

The engine returns a JSON object with the evaluation result:

{
  "result": true,
  "trace": [
    "Evaluating rule: A **Person** gets approved",
    "Checking: __age__ of **Person** is greater than 18",
    "Value: 25 > 18 = true",
    "Rule passed"
  ]
}

Field	Type	Description
result	boolean	Whether the policy passed (true) or failed (false)
trace	string[]	Step-by-step evaluation trace
error	string	Error message if the rule failed to parse

Error Handling

If the rule text is invalid or the data is missing required fields, the engine returns an error:

{
  "result": false,
  "error": "Parse error: unexpected token at line 1"
}

Common errors:

• Parse error — the rule syntax is invalid
• Missing selector — the data doesn’t contain the referenced selector
• Missing property — the data doesn’t contain the referenced property

Try It

Interactive Example

Reset

Policy Rule

A **Person** gets approved if __age__ of **Person** is greater than 18 and __email__ of **Person** is a valid email.

Test Data (JSON)

{ "Person": { "age": 25, "email": "alice@example.com" } }

▶ Run

Multi-Rule Evaluation

Send multiple rules in a single request. The engine evaluates all rules and returns the result of the last rule (the golden rule):

curl -X POST https://api.policy.keloran.dev/run \
  -H "Content-Type: application/json" \
  -d '{
    "rule": "A **user** passes age check if __age__ of **user** is at least 18.\n\nA **user** is eligible if the **user** passes age check.",
    "data": { "user": { "age": 25 } }
  }'