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

# browser_use

> Step function: browser_use

<Warning>
  Any action whose `steps[]` includes `browser_use` **must** declare `executionMode: async` on the action. The runtime enforces this — a sync action containing `browser_use` fails schema validation at build time.
</Warning>

## Input

<Tabs>
  <Tab title="v1">
    <table>
      <colgroup>
        <col width="210" />

        <col width="400" />

        <col width="90" />

        <col width="90" />
      </colgroup>

      <thead>
        <tr>
          <th>Field</th>
          <th>Description</th>
          <th>Type</th>
          <th>Required</th>
        </tr>
      </thead>

      <tbody>
        <tr>
          <td>[`auth`](#auth)</td>
          <td>Credential handling for the browser task.</td>
          <td>object</td>
          <td>No</td>
        </tr>

        <tr>
          <td>[`budgets`](#budgets)</td>
          <td>Execution limits the task must run within.</td>
          <td>object</td>
          <td>Yes</td>
        </tr>

        <tr>
          <td>`locale`</td>
          <td>Locale the browser session runs in.</td>
          <td>string</td>
          <td>No</td>
        </tr>

        <tr>
          <td>`startUrl`</td>
          <td>URL where the browser session begins.<br />Format: `uri`</td>
          <td>string</td>
          <td>Yes</td>
        </tr>

        <tr>
          <td>`systemPrompt`</td>
          <td>Author-defined preamble, persona, and guardrails applied to every invocation.</td>
          <td>string</td>
          <td>No</td>
        </tr>

        <tr>
          <td>[`viewport`](#viewport)</td>
          <td>Browser viewport dimensions.</td>
          <td>object</td>
          <td>No</td>
        </tr>
      </tbody>
    </table>

    <AccordionGroup>
      <Accordion title="auth">
        Credential handling for the browser task.

        <table>
          <colgroup>
            <col width="210" />

            <col width="400" />

            <col width="90" />

            <col width="90" />
          </colgroup>

          <thead>
            <tr>
              <th>Field</th>
              <th>Description</th>
              <th>Type</th>
              <th>Required</th>
            </tr>
          </thead>

          <tbody>
            <tr>
              <td>`allowedDomains`</td>
              <td>Overrides the default allowed-domains policy, for auth flows that cross a domain boundary.</td>
              <td>string\[]</td>
              <td>No</td>
            </tr>

            <tr>
              <td>`requiresSession`</td>
              <td>Reserved for tasks that need a pre-authenticated browser session rather than form substitution. Not yet in use.</td>
              <td>boolean</td>
              <td>No</td>
            </tr>

            <tr>
              <td>`sensitiveKeys`</td>
              <td>Credential keys masked from the LLM and substituted only at the typing layer.</td>
              <td>string\[]</td>
              <td>No</td>
            </tr>
          </tbody>
        </table>
      </Accordion>

      <Accordion title="budgets">
        Execution limits the task must run within.

        <table>
          <colgroup>
            <col width="210" />

            <col width="400" />

            <col width="90" />

            <col width="90" />
          </colgroup>

          <thead>
            <tr>
              <th>Field</th>
              <th>Description</th>
              <th>Type</th>
              <th>Required</th>
            </tr>
          </thead>

          <tbody>
            <tr>
              <td>`maxDurationMs`</td>
              <td>Maximum task duration in milliseconds.</td>
              <td>integer</td>
              <td>Yes</td>
            </tr>

            <tr>
              <td>`maxSteps`</td>
              <td>Maximum number of steps the agent may take.</td>
              <td>integer</td>
              <td>Yes</td>
            </tr>
          </tbody>
        </table>
      </Accordion>

      <Accordion title="viewport">
        Browser viewport dimensions.

        <table>
          <colgroup>
            <col width="210" />

            <col width="400" />

            <col width="90" />

            <col width="90" />
          </colgroup>

          <thead>
            <tr>
              <th>Field</th>
              <th>Description</th>
              <th>Type</th>
              <th>Required</th>
            </tr>
          </thead>

          <tbody>
            <tr>
              <td>`height`</td>
              <td>Viewport height in pixels.</td>
              <td>integer</td>
              <td>Yes</td>
            </tr>

            <tr>
              <td>`width`</td>
              <td>Viewport width in pixels.</td>
              <td>integer</td>
              <td>Yes</td>
            </tr>
          </tbody>
        </table>
      </Accordion>
    </AccordionGroup>
  </Tab>
</Tabs>

## Output

<Tabs>
  <Tab title="v1" />
</Tabs>