Alerts and webhooks

Managed Production tells you when something happens to a Workflow — by email, by webhook, or both. Configure both under Settings → alerts in the dashboard, or PUT /v1/settings/alerts.

What you’re told about

Event	When	Can be turned off
`drift`	A settled Step’s model stopped passing; its backup now serves while it’s re-searched.	yes
`resettled`	A re-search finished and the Step has a new winner.	with drift
`failover`	A model failed and a backup served the call.	yes
`spend_alert`	Spend this month crossed your alert threshold.	no
`spend_cap`	Spend reached your monthly cap; calls are paused (402).	no
`billing_failed`	An auto top-up or a subscription renewal couldn’t be charged.	no
digest	A monthly summary per Workflow.	yes

Every event is also listed on the Workflow’s Production tab.

Email

On by default, to your account’s address. Add up to ten more recipients — an on-call alias, a shared inbox. Each email links to the Workflow’s Production tab and to the alert settings.

Webhooks

Set a URL and Shimmy POSTs each event as JSON:

{
  "type": "failover",
  "workflow_id": "099730af-…",
  "step_fingerprint": "da4f6f8aa1bc7385",
  "detail": { "from": "gpt-4.1", "to": "gpt-5.5", "reason": "unavailable" },
  "at": "2026-10-02T20:25:05Z"
}

Two headers come with it: x-shimmy-event (the type) and x-shimmy-signature — sha256= and the hex HMAC-SHA256 of the raw body, keyed by your webhook secret. Verify it before trusting the body:

import { createHmac, timingSafeEqual } from 'node:crypto';

function verify(rawBody: Buffer, header: string, secret: string): boolean {
  const expected = 'sha256=' + createHmac('sha256', secret).update(rawBody).digest('hex');
  return header.length === expected.length &&
    timingSafeEqual(Buffer.from(header), Buffer.from(expected));
}

The secret is generated when you first set a webhook; show or rotate it in the alert settings. A failed delivery is retried once.

Spend caps

Set a monthly cap and the percentage at which to warn. At the cap, Shimmy stops serving the account’s calls with 402 spend_cap_reached until the month turns or you raise it — a guard against a runaway loop, not a budget you expect to hit.