pass_series.* events

A cancelled date in a season was replaced, and one holder was moved to the replacement.

When this fires

A creator cancelled a window that a season ticket points at, a replacement was available, and one holder was moved onto it. Their season carries on at the same length.

Fires once per holder, not once per cancellation. Each holder is resettled individually because the outcomes differ: someone already holding the replacement date skips past it to the next one they do not have, and someone with no replacement available is dropped instead.

Caveats

  • was_queued is the field worth branching on. A holder who was queued stays queued for the new date and is told there is nothing to do. One who was not usually gets their invite link attached, except a holder who had already been admitted to the cancelled window: they also report was_queued: false, but their access is revoked and they are told a fresh link arrives when the new window opens, so no link is attached. was_queued: false therefore covers two different situations; if you need to tell them apart, check whether the holder currently has access. If you send your own message alongside ours, match that split or you will ask half your audience to do something they have already done.
  • The holder is never moved onto a date they already hold. The next one they do not have is chosen instead, so to_window_id can be further out than the immediate next window.
  • Three groups are skipped entirely and produce no event: holders who are paused, past due, or who cancelled their own series. They still paid for a date that is not happening. Check subscriptions on that plan before reaching for a refund list.
  • plan_id is the source plan. To identify the series, read subscription_id.

Related events

  • pass.holder_moved: the same resettlement on an ordinary single-window pass rather than a series.
  • pass_series.leg_dropped: what happens when no replacement exists.
  • pass.window_cancelled: fires once, last, carrying both tallies.
postWebhookpass_series.leg_substituted

Headers

SB-Signaturestring required

t=<unix seconds>,v1=<hex>: the HMAC-SHA256 of "<t>.<raw body>" under the endpoint's secret. Verify it before acting, and refuse a t more than 300 seconds from now. During a secret rotation a v0= signature under the previous secret may precede v1=.

SB-Event-Idstring required

The event's ULID, bare. The envelope's id is the same ULID prefixed evt_, so strip the prefix before comparing. Deduplicate on it: a retry carries the same id.

SB-Event-Namestring required

The event name, the same as the envelope's type.

Content-Typestring required

Always application/json.

User-Agentstring required

Always Subscriby-Webhooks/1.0.

Payload

idstring required

A ULID unique to the event, prefixed evt_. Every retry carries the same id, so it is the key to deduplicate on.

type'pass_series.leg_substituted' required

The event name, always pass_series.leg_substituted here.

created_atstring date-time required

When the event was emitted, server time, ISO 8601.

api_versionstring required

The contract version of the payload shape, 2026-05-01 today. A breaking change to a shape ships under a new version.

project_idstring uuid nullable required

The project the event belongs to; null for team-scoped and billing events.

Response

Your endpoint acknowledged the delivery. Any 2xx status within 30 seconds marks it delivered; the response body is ignored.

Changes

Webhooks have no change history: a webhook is keyed by its event name rather than a path and method, so no recorded change can name it.