nips/35.md

NIP-35

Member List

draft optional author:arthurfranca

Groups, channels, communities and the like may use status events to dynamically build a member list.

Motivation

An user may never send a message to a group but still want to be on a group member list for receiving DMs.

Also one may want to discover his friends' groups.

Status Event

It is a kind 34549 parameterized replaceable event (PRE) with:

• d tag is a reference to the group creation event as <kind>:<pubkey>:<d-identifier> if PRE or <kind>:<pubkey> if replaceable or <event id> if regular event;
• k tag as <group creation event kind> for discoverability;
• optional status tag (see "Custom Status" section);
• NIP-40 expiration tag that should be 60 days ahead of the created_at tag value;
• .content as stringified author kind 0 event JSON for fast lookup.

The event should be replaced by clients from time to time (lower than 10 min window - see "Basic Status" section), for example every 7 minutes the user is browsing a group.

If the created_at tag age (now - created_at) is higher than 10 minutes, the client should consider the .content stale for important things such as zap address.

{
  "id": "<32-bytes lowercase hex-encoded SHA-256 of the the serialized event data>",
  "pubkey": "<32-bytes lowercase hex-encoded public key of the event creator>",
  "created_at": "<Unix timestamp in seconds>",
  "kind": 34549,
  "tags": [
    ["d", "f39e9b451a73d62abc5016cffdd294b1a904e2f34536a208874fe5e22bbd47cf"],
    ["k", "40"],
    ["status", "Feeling gOoOod"]
    ["expiration", "<Unix timestamp in seconds>"]
  ],
  "content": "{<author kind 0 JSON>}"
  "sig": "<64-bytes hex of the signature of the sha256 hash of the serialized event data>"
}

Basic Status

Basic status don't rely on status tags. Clients find out the user status by the following rules regarding status event's created_at age:

Age	Status
(now - created_at) < 0	invalid status, not a member
0 <= (now - created_at) < 10min	online
10 min <= (now - created_at) < 30 min	away
30 min <= (now - created_at) < 5 days	offline
5 days <= (now - created_at) < 60 days	inactive
60 days <= (now - created_at)`	not a member

An user is invisible if it deletes the status event or had never published it. Invisible should be the default status when joining (browsing) a group.

Custom Status

Clients can choose to support extra custom status that may override the basic ones by using status tags; even multiple status tags at once.

The following are the standardized status tag values:

• "online"
• "away"
• "offline"
• "inactive"
• "busy"
• "free-for-chat"