NIP-96
======

Push Notification Server API
----------------------------

`draft` `optional`

This NIP defines a common API to register push notification tokens into an event watcher server. The goal is to allow users to choose their push notification servers by simply adding an http address to their account. 

## Registration Call

After receiving a `token` from the push system (Google Services, Unified Push, Apple Push Notification), clients should upload a list of signed NIP-98 events, one for each account in the device, in a `POST` to `/register` with the following body:

```jsonc
{
  "events": [ 
    {
      "id": "..",
      "pubkey": "...",
      "created_at": ...,
      "kind": 22242,
      "tags":[
        [ "relay","<inbox relay 1>" ],
        [ "relay","<inbox relay 2>" ],
        [ "challenge", "<system>:<token>" ]
      ],
      "content":"",
      "sig":"..."
    }
  ]
}
```

where `system` is `google`, `apple` or `unifiedpush`.

Servers will use the `system` information to select where to send new events from the relays marked as such.

The server returns with an array of 

```jsonc
  [
    {
        "pubkey": "<pubkey>",
        "result": "<added|replaced|error>",
        "error": "<message>",
    }
  ]
```

Servers SHOULD accept multiple tokens per pubkey, but may limit the number of them.

Servers SHOULD delete tokens after failure to deliver.

## Sending Events

Servers send new events via the user's preferred system. The event is [NIP-59 GiftWrapped](59.md) to the receiver, but no `p`-tag is added to the wrap event. In that way, the chosen system cannot know which key is receiving this event.

Clients SHOULD try to decrypt the GiftWrap with all logged-in accounts. 

## Event Watcher Server list

An Event Watcher Server list is a kind 10097 replaceable event meant to select one or more servers the user wants
to register for push notifications. Servers are listed as `server` tags:

```json
{
  "kind": 10097,
  "content": "",
  "tags": [
    ["server", "https://push.amethyst.social"],
    ["server", "https://server2.com"],
  ]
}
```