NIP-91
======

EOSE Extensions
---------------

`draft` `optional`

This NIP defines an extension to the EOSE message that allows relays to convey additional information to clients.

## Extended EOSE

An extended EOSE is an EOSE message, with the 2nd parameter being the "extensions object". For example: `["EOSE","example-sub",{"example_ext":"example value"}]`

An EOSE extension is a field in the extensions object. This may contain any value.

Experimental extensions SHOULD use the `x_` prefix for the object key.

Clients MUST NOT rely on relays implementing any extensions.

## Extensions

This NIP defines a set of standard extensions.

### `next_created_at`
`recommended`

The value of this extension MUST be an integer if present, and should specify the next `until` value the client should use for pagination.
This MAY be higher or lower than the lowest `created_at`, and the clients SHOULD NOT perform any modifications to this value.

### `cursor`

The value of this extension MUST be a string if present, and represents a cursor the client can use to paginate this query.
To get more events, the client MUST send a `REQ` with the same filters (except limit, which can be changed), and the `cursor` string
in the 1st filter with the key `cursor`. Example:
```jsonc
< ["REQ", "examplereq1", {"kinds": [1], "limit": 1}, {"authors": ["..."], "limit": 1}]
> ["EVENT", "examplereq1", ...]
> ["EOSE", "examplereq1", {"cursor": "example-cursor-string", ...}]
< ["CLOSE", "examplereq1"]
< ["REQ", "examplereq2", {"kinds": [1], "limit": 5, "cursor": "example-cursor-string"}, {"authors": ["..."], "limit": 5}]
> ["EVENT", "examplereq2", ...]
...
```

This cursor MUST be valid for the duration of the connection, and MAY be valid in a new connection. A relay may indicate a cursor is no longer valid
by sending a CLOSED with the prefix `bad-cursor: `.

### `has_more`
`recommended`

The value of this extension MUST be a boolean if present, and should represent if the client should continue trying to get events.
This MAY be false if the relay has completed the query due to not having more events available, or may not be able to complete this query due to a permanent failure (scan limit exceeded is one).