> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nika.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# for_each

> Contract, placement, related fields and source examples for this Nika YAML field.

[Language reference](/reference/language/overview) / `for_each`

## Meaning and placement

### task

Fan this task out over a collection · ONE block, so the concurrency is visible where the fan-out is declared. `max_parallel` and `fail_fast` live here because they have no meaning without it.

| Property             | Declaration                       |
| -------------------- | --------------------------------- |
| Requirement          | Optional in this object           |
| Schema location      | `/$defs/task/properties/for_each` |
| type                 | "object"                          |
| additionalProperties | false                             |

**In the same object:** [after](/reference/language/words/after) · [agent](/reference/language/words/agent) · [exec](/reference/language/words/exec) · [extract](/reference/language/words/extract) · [group](/reference/language/words/group) · [infer](/reference/language/words/infer) · [invoke](/reference/language/words/invoke) · [lift](/reference/language/words/lift) · [on\_error](/reference/language/words/on_error) · [retry](/reference/language/words/retry) · [returns](/reference/language/words/returns) · [timeout](/reference/language/words/timeout) · [when](/reference/language/words/when) · [with](/reference/language/words/with)

[Schema source (use the pointer above)](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/schemas/workflow.schema.json)

## In a source template

Excerpt from `templates/fanout.nika.yaml`, source lines 98–107. This is a fragment, not a runnable workflow.

```yaml illustration theme={"system"}
  read:
    with:
      discover: ${{ tasks.discover.output }}
    for_each:
      items: ${{ with.discover }}
      max_parallel: 8
      fail_fast: false
    on_error:
      recover: null                 # an unreadable item yields null · the batch lives
    invoke:
```

### Templates containing this field

| Template                     | Source                                                                                                                               |
| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| `templates/fanout.nika.yaml` | [Line 101](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/fanout.nika.yaml#L101) |

These are literal key occurrences in the source files, not an execution or conformance claim. [How to instantiate a template](/guides/templates).

## Contract and implementation

This page projects the named specification revision. Check [released engine status](/reference/status) and [the validation workflow](/guides/agent-authoring) before running a file. An optional field is not evidence that every engine supports every value.

Canonical identity: `language:word:for_each`. Spec revision: [`c5ebbb7b862b`](https://github.com/supernovae-st/nika-spec/tree/c5ebbb7b862b68bc6cf7235efba61173b844afc6).

[How documentation stays connected](/reference/knowledge-system).