## Upload

File upload

```
POST /v1/files
Authorization: Bearer $HR_API_KEY
Content-Type: multipart/form-data

purpose=user_data
file=@agreement.docx
```

## Reference in input

Input file content block

```
{
  "input": [
    {
      "role": "user",
      "content": [
        { "type": "input_file", "file_id": "file_..." },
        { "type": "input_text", "text": "Review this agreement." }
      ]
    }
  ],
  "stream": true
}
```

**Open standard**  
Multipart upload to /v1/files followed by an input_file content block is one of the two input forms — upload by id or inline data URL — that UHP's Files chapter requires servers to accept. See [file input in UHP's Files chapter](https://unifiedharnessprotocol.org/spec/files).