LexQ examples

How to integrate LexQ into your backend service.

LexQ is called server-side: your service gathers the facts, calls the LexQ Execution API, and uses the decision it returns. The API key never reaches a browser.

The Execution API

• Base URL: https://api.lexq.io/api/v1/execution
• Auth: every request sends an x-api-key header

Create the key in the Console under Management → API Keys. The default Execute only scope is all these examples need, and it is the right one for a key embedded in your service. Manage exists for policy tooling such as the CLI, and granting it here would hand your application write access it never uses. See API key scopes.

LexQ has four execution modes. This repo's example uses Single Group — the standard path for evaluating one decision:

Mode	Endpoint
Single Group	POST /groups/{groupId}
Specific Version	POST /groups/{groupId}/versions/{versionId}
Batch	POST /groups/{groupId}/batch
Composite	POST /composite

Full reference: https://docs.lexq.io/api/execution

Request

POST /api/v1/execution/groups/{groupId}
x-api-key: <your-api-key>
Content-Type: application/json
Idempotency-Key: <your-order-id>      # optional — prevents duplicate execution

{ "facts": { "paymentAmount": 150000, "customerTier": "VIP" }, "context": {} }

facts is required; context is optional metadata passed to actions. To see which facts a deployed policy needs: GET /api/v1/execution/groups/{groupId}/requirements.

Idempotency-Key is capped at 255 characters. LexQ rejects a longer key with I-003 / 400 rather than truncating it, because two different keys must never collapse into one and replay each other's result. These examples pass the order ID straight through, so if your IDs can exceed that, hash them first.

Response

{
  "result": "SUCCESS",
  "data": {
    "traceId": "2e31f2b8-...",       // the execution's audit handle
    "inputFacts": { ... },
    "mutatedFacts": { ... },         // facts changed by rule actions
    "generatedVariables": { ... },
    "executionTraces": [ ... ],
    "decisionTraces": [ ... ]
  }
}

Store data.traceId next to your own records — it is how you later look up exactly which rules produced this decision.

Worked example

• typescript/ — a runnable pricing service
• java/ — the same pricing service, Spring Boot