Sub-Workflow block

Configure the Sub-Workflow block to call another workflow as a step, pass inputs to it and use the outputs it returns in later steps.

The Sub-Workflow block (type: "subworkflow") starts another workflow in your company as a child run, passes it an input, and by default waits for its result. For the plain-language guide, see Reuse one workflow inside another.

When to use it

Keep one "post a journal entry" workflow and call it from several month-end workflows.
Process each entity or customer in its own child run, so one failure does not hide the rest.
Split a large workflow into parts that can be tested and deployed on their own.

Configuration

Field (`config` key)	Editor label	Type	Required	Meaning
`workflowId`	Workflow	string	Yes	The id of the workflow to run. It must belong to your company and be deployed (status `active`).
`input`	Input Mapping	object	No	The child run's input. Use template references, such as `{ "customerId": "{{steps.lookup.id}}" }`. Must be an object; empty means `{}`.
`waitForCompletion`	Wait for Completion	boolean	No	Default `true`. When `false`, the step starts the child and continues without its result.
`timeoutMinutes`	Timeout (minutes)	number	No	How long to wait for the child. Default 5, at most 1440 (24 hours). Used only when waiting.
`idempotencyKey`	Idempotency Key	string	No	A stable key, such as `close-{{input.period}}-{{input.entityId}}`. A second call with the same key reuses the existing child run instead of starting another. A failed or cancelled child with that key is started again.
`queueName`	Queue Name	string	No	A named queue for child runs.
`queueConcurrencyLimit`	Queue Concurrency Limit	number	No	1 to 20. The most child runs active in the queue at once, shared by every Sub-Workflow step in the company that uses the same queue name. Needs `queueName`.
`machine`	Compute Capacity	string	No	`standard` (default, the child's own setting), `medium-1x`, `medium-2x` or `large-1x`. Higher capacity costs more per minute of run time.
`maxDurationSeconds`	Time Limit (seconds)	number	No	The child run's time limit, at least 5. Blank uses the child workflow's own limit.

Older workflows may hold inputMapping or timeout (milliseconds). These are moved to input and timeoutMinutes when the workflow is saved or run. If an old value disagrees with the new field, the editor shows it as Legacy Input Mapping or Legacy Timeout (milliseconds) and the run fails until you clear it.

Output

When the step waits:

Field	Type	Meaning
`output`	any	The child run's output. Read it as `{{steps.<step id>.output.<path>}}`.
`status`	string	`completed`.
`subworkflowId`	string	The child workflow id.
`subworkflowRunId`	string	The child run id.
`waitedForCompletion`	boolean	`true`.
`reusedExistingRun`	boolean	`true` when an idempotency key matched an existing child run.
`durationMs`	number	Time spent waiting.

When waitForCompletion is false, the output has subworkflowId, subworkflowRunId, status (triggered, or the reused run's status), waitedForCompletion: false and reusedExistingRun.

The editor's output list shows result and runId; the executor returns output and subworkflowRunId. Here output is a field of this step's result, so {{steps.<step id>.output.<path>}} is correct for this block.

Example

This step runs a "Post accrual" workflow for each entity in a loop, keyed so a retry does not post twice.

{
  "id": "post_accrual",
  "type": "subworkflow",
  "name": "Post accrual for entity",
  "config": {
    "workflowId": "5b0d3c2a-1e4f-4a6b-8c9d-0e1f2a3b4c5d",
    "input": {
      "entityId": "{{variables.entity.id}}",
      "period": "{{input.period}}",
      "amount": "{{variables.entity.accrual}}"
    },
    "waitForCompletion": true,
    "timeoutMinutes": 15,
    "idempotencyKey": "accrual-{{input.period}}-{{variables.entity.id}}"
  }
}

Errors and limits

The step fails when the workflow is not found, not deployed, or belongs to another company.
The step fails when input is missing a field the child's inputSchema marks as required.
A failed or cancelled child run fails the step with the child's error. A child that does not finish within timeoutMinutes fails the step; the child keeps running.
The wait counts toward the parent run's time limit. If the parent is near its limit, the step fails and the child keeps running. Raise the parent's time limit, or turn Wait for Completion off.
queueConcurrencyLimit without queueName fails the step.
A {{secrets.KEY}} reference in a Sub-Workflow step's config stops the run before it starts. Reference the secret inside the child workflow instead.