Add NIP-35 - Member List

35.md

@@ -0,0 +1,81 @@
+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](#custom-status));
+- [NIP-40](40.md) `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](#custom-status)),
+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.
+
+
+```js
+{
+  "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"