> ## 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.

# url

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

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

## Meaning and placement

### infer → vision · items

The schema declares this field at the location below.

| Property        | Declaration                                           |
| --------------- | ----------------------------------------------------- |
| Requirement     | Optional in this object                               |
| Schema location | `/$defs/infer/properties/vision/items/properties/url` |
| type            | "string"                                              |

**In the same object:** [path](/reference/language/words/path) · [source](/reference/language/words/source)

[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/api-upload-and-create.nika.yaml`, source lines 69–78. This is a fragment, not a runnable workflow.

```yaml illustration theme={"system"}
    invoke:
      tool: "nika:fetch"
      args:
        url: "${{ const.api_base }}/items"   # SLOT: the create endpoint
        method: POST
        headers:
          x-api-key: "${{ secrets.API_KEY }}"  # SLOT: the auth header name
        multipart:
          # Exactly one of `path:` (file) or `value:` (text) per part — a part
          # carrying both, or neither, is refused before anything is sent.
```

### Templates containing this field

| Template                                    | Source                                                                                                                                            |
| ------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| `templates/api-upload-and-create.nika.yaml` | [Line 72](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/api-upload-and-create.nika.yaml#L72) |
| `templates/etl-state.nika.yaml`             | [Line 106](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/etl-state.nika.yaml#L106)           |
| `templates/gate-and-act.nika.yaml`          | [Line 55](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/gate-and-act.nika.yaml#L55)          |
| `templates/website-brief.nika.yaml`         | [Line 54](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/website-brief.nika.yaml#L54)         |

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:url`. Spec revision: [`c5ebbb7b862b`](https://github.com/supernovae-st/nika-spec/tree/c5ebbb7b862b68bc6cf7235efba61173b844afc6).

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