Common types

`Error`

Field	Type	Required	Notes
`reason`	`BadRequest` \| `NotFound` \| `TooLarge` \| `Unauthorized` \| `Forbidden` \| `Conflict` \| `Internal` \| `Unavailable`	Yes	Machine-readable category
`message`	`string`	Yes	Human-readable explanation

The following table maps HTTP codes to their respective reason:

Field	Type	Required	Notes
`cursor`	`string`		Opaque cursor token for the next page

Field	Type	Notes
`limit`	`int`	Soft page-size cap; server may return fewer
`cursor`	`string`	Cursor from a previous list response
`selector`	`string`	Selector expression (see filtering)