Billing notifications — frontend integration

Two new notification types now reach the client when a workspace's subscription changes state. Additive only — no existing payload changed, but an unknown type will fall through your notification renderer if you switch on it.

New notification types

`type`	When
`subscription_canceled`	The user canceled via `POST /user/billing/cancel`, or the gateway terminated the subscription (external cancel, dunning exhausted, term expired)
`subscription_renewed`	A recurring charge succeeded and advanced the billing period. The first charge (activation) does not notify.

Both are delivered on two channels:

In-app — a row in GET /api/v1/notifications, exactly like assignment and mention notifications.
FCM push — a visible notification with a clickAction pointing at the billing settings page.

Recipients

Every super-admin of the workspace (super_admin = true, is_active = true). Regular members are not notified — billing is the owner's concern.

In-app shape

{
  "id": 812,
  "type": "subscription_renewed",
  "title": "Subscription renewed",
  "message": "Your Advanced plan renewed. Next charge on 2026-03-10.",
  "action_url": "/en/settings/billing",
  "is_read": false,
  "data": {
    "type": "subscription_renewed",
    "plan_name": "Advanced",
    "workspace_name": "Acme",
    "period_end": "2026-03-10",   // key omitted when the sub carries no period
    "frontend_url": "https://acme.corteksa.net/en/settings/billing",
    "notification_type": "subscription_renewed",
    "timestamp": "2026-02-10T00:00:00.000Z"
  }
}

performed_by is null on these — nobody in the workspace performed the action. object_slug / record_slug are present but empty, as on any non-record notification.

Copy for the canceled case:

title: Subscription canceled
message: Your {plan} plan was canceled. {workspace} keeps access until {period_end}. — the date clause is dropped when period_end is empty.

period_end means access end for a cancellation (the workspace keeps working until then, per the existing lapse ladder) and next charge date for a renewal. Format is YYYY-MM-DD.

Push shape

Same data keys as above, plus the standard title / body. The FCM collapseKey is subscription_subscription_canceled / subscription_subscription_renewed, so a newer lifecycle notification replaces an unread older one on the device instead of stacking.

Filtering

GET /notifications?type= still accepts only all | assign | comment. Billing notifications are returned under all; there is no dedicated filter value yet. Unread counts include them.