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

# SessionCostMeta

## Fields

| Field           | Type                                                                                    | Required             | Description                                                                                    | Example                  |
| --------------- | --------------------------------------------------------------------------------------- | -------------------- | ---------------------------------------------------------------------------------------------- | ------------------------ |
| `AsOf`          | `string`                                                                                | :heavy\_check\_mark: | ISO-8601 timestamp when the response was generated.                                            | 2026-05-12T02:00:00.000Z |
| `Version`       | [components.SessionCostMetaVersion](../../models/components/sessioncostmetaversion.mdx) | :heavy\_check\_mark: | Dataset version.                                                                               |                          |
| `WindowDays`    | `*int64`                                                                                | :heavy\_check\_mark: | Number of days in the weekly session sample window, or null when no snapshot is published.     | 30                       |
| `WindowEndDate` | `*string`                                                                               | :heavy\_check\_mark: | UTC date of the final day in the session sample window, or null when no snapshot is published. | 2026-05-11               |