Public Messages (#1988)

A4.md

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+NIP-A4
+======
+
+Public Messages
+---------------
+
+`draft` `optional`
+
+This NIP defines kind `24` as a simple plaintext message to one or more Nostr users. 
+
+The `.content` contains the message. `p` tags identify one or more receivers.
+
+```jsonc
+{
+  "pubkey": "<sender-pubkey>",
+  "kind": 24,
+  "tags": [
+    ["p", "<receiver>", "<relay-url>"],
+  ],
+  "content": "<message-in-plain-text>",
+}
+```
+
+Messages MUST be sent to the [NIP-65](65.md) inbox relays of each receiver and the outbox relay of the sender.
+
+Kind `24` is designed to be shown and replied to from notification screens. The goal is to allow clients to 
+support this feature without having to worry about chat history. There are no message chains. The concept of a 
+"thread", a "thread root", or a "chatroom" does not exist in this system, as messages can start and continue 
+without any syntactic connection to each other. `e` tags must not be used.
+
+This kind is not designed to be displayed on feeds, but anyone can see and reply to messages that may not be for them.
+
+## Advanced Support
+
+[NIP-40](40.md) `expiration` tags are recommended. Since there is no concept of a chatroom, it is unlikely that these messages will 
+make sense as time goes on.
+
+[NIP-18](18.md) quote repost `q` tags MAY be used when citing events in the `.content` with [NIP-21](21.md).
+
+```json
+["q", "<event-id> or <event-address>", "<relay-url>", "<pubkey-if-a-regular-event>"]
+```
+
+[NIP-25](25.md) reactions MUST add a `k` tag to `24`. 
+
+[NIP-57](57.md) zaps MUST include the `k` tag to `24`
+
+[NIP-21](21.md) links that use [NIP-19](19.md)'s `nevent1` MUST include a `kind` of `24`. Links that are not `kind:24` are not expected to be rendered natively by the client.
+
+[NIP-92](92.md) `imeta` tags SHOULD be added for image and video links.
+
+## Warnings
+
+There MUST be no expectation of privacy in this kind. It is just a public reply, but without a root note.
+
+Avoid confusing this kind with Kind `14` rumors in [NIP-17](17.md) DMs. This kind is signed and designed for public consumption.