Adds a step to the campaign's draft sequence and returns it. Appends to the end by default; pass after (a node_id) to insert after a specific step.

type is a catalog id from List Sequence Step Types. config is merged over that type's default_config — required fields must end up set (a send step needs subject and body).

Wait steps between steps are managed automatically and cannot be added directly; patch a wait step's config to change a delay.

This writes the draft. Call Publish Sequence to make it live.

Concurrent writes are safe — overlapping calls to one campaign serialize, and every change is kept. A sequence builder open in the browser saves its own copy of the whole graph, so an edit made through the API while that canvas is open is overwritten by the next canvas save.

{
  "data": {
    "node_id": "send-m2k9x1p-0"
  }
}