Monitors

Parameters

Create

curl -X POST https://www.contrie.com/api/v1/monitors \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $CONTRIE_API_KEY" \
  -d '{
    "url": "https://example.com/widget",
    "extract": "price, availability",
    "every": 60,
    "webhookUrl": "https://hooks.example.com/contrie"
  }'

The response is 201 with monitor, baseline and, when you gave a webhook, webhookSecret (shown once). If the baseline is refused, the monitor is still created and active, and baseline is { "success": false, "data": null, "error": { "code", "message" } } — the full response when a rejected answer exists. A refusal costs 0 credits. Read baseline.error.code: PAGE_LIMIT_REACHED resumes when credits return; SOURCE_REFUSED usually keeps refusing, so stop that monitor — unless its message says the source is rate-limiting, which can recover on a later run. Past your plan’s cap, creation returns 429 PAGE_LIMIT_REACHED and nothing is created.

A change event

{
  "id": "…",
  "kind": "change",
  "at": "2026-09-08T14:15:03.201Z",
  "diff": [ { "path": "$.price", "before": 24.99, "after": 19.99 } ],
  "before": { "success": true, "data": { "price": 24.99, "availability": "in stock" }, "metadata": { "evidenceStatus": "signed", "evidence": { "…": "…" } } },
  "after":  { "success": true, "data": { "price": 19.99, "availability": "in stock" }, "metadata": { "evidenceStatus": "signed", "evidence": { "…": "…" } } }
}

Events are baseline, change and error; GET /api/v1/monitors/:id returns the latest 20. An error event’s after is the failure with its public error.code and message. A run that fails exactly like the latest event updates that event instead of adding one: its at becomes the newest failure, so a page that keeps refusing cannot push your changes out of those 20, and a failure after a recovery still shows as the newest event. The diff itself is not signed.

Webhook

One POST per change, with this body:

{
  "event": "monitor.change",
  "monitorId": "…",
  "url": "https://example.com/widget",
  "changedAt": "2026-09-08T14:15:03.412Z",
  "diff": [ { "path": "$.price", "before": 24.99, "after": 19.99 } ],
  "before": { "success": true, "data": { "…": "…" }, "metadata": { "…": "…" } },
  "after":  { "success": true, "data": { "…": "…" }, "metadata": { "…": "…" } }
}

Only changes are delivered; errors are not. It is signed the way Stripe signs: X-Contrie-Signature: t=<unix>,v1=<hex> where v1 is HMAC-SHA256 of t + "." + body with your monitor’s secret. Reject stale timestamps. Delivery is one attempt; the event is stored either way and readable from the monitor.

Credits per day

Credits per day = runs per day × credits per accepted run, and runs per day = 1,440 ÷ every. An accepted run costs what one extraction costs: at least 1 credit, at most the plan’s per-request cap (Free 3, Builder 5, Pro 17), rendering included. Refused and rejected runs cost 0 credits. A monitor keeps spending until you stop it.

One default monitor at 1 credit a run spends the Free plan’s 200 monthly credits in about 8 days; at every: 15, in about 2. Active monitors per plan: 3 Free, 25 Builder, 100 Pro.

List, read and stop

GET /api/v1/monitors lists your active monitors. GET /api/v1/monitors/:id returns one with its events. DELETE /api/v1/monitors/:id stops one; it and its history stay readable by id (active: false). From MCP: contrie_watch creates, contrie_monitors lists, contrie_changes reads a monitor’s events, and contrie_unwatch stops one. Stopping one that is already stopped differs: REST DELETE returns 404, while contrie_unwatch succeeds and returns the monitor unchanged.