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+
+NIP-28
+======
+
+Public Chat
+-----------
+
+`draft` `optional` `author:ChristopherDavid` `author:fiatjaf` `author:jb55` `author:Cameri`
+
+This NIP defines new event kinds for public chat channels, channel messages, and basic client-side moderation.
+
+It reserves five event kinds (40-44) for immediate use and five event kinds (45-49) for future use.
+
+- `40 - channel create`
+- `41 - channel metadata`
+- `42 - channel message`
+- `43 - hide message`
+- `44 - mute user`
+
+Client-centric moderation gives client developers discretion over what types of content they want included in their apps, while imposing no additional requirements on relays.
+
+## Kind 40: Create channel
+
+Create a public chat channel.
+
+In the channel creation `content` field, Client SHOULD include basic channel metadata (`name`, `about`, `picture` as specified in kind 41).
+
+```json
+{
+    "content": "{\"name\": \"Demo Channel\", \"about\": \"A test channel.\", \"picture\": \"https://placekitten.com/200/200\"}",
+    ...
+}
+```
+
+
+## Kind 41: Set channel metadata
+
+Update a channel's public metadata.
+
+Clients and relays SHOULD handle kind 41 events similar to kind 0 `metadata` events.
+
+Clients SHOULD ignore kind 41s from pubkeys other than the kind 40 pubkey.
+
+Clients SHOULD support basic metadata fields:
+
+- `name` - string - Channel name
+- `about` - string - Channel description
+- `picture` - string - URL of channel picture
+
+Clients MAY add additional metadata fields.
+
+Clients SHOULD use [NIP-10](10.md) marked "e" tags to recommend a relay.
+
+```json
+{
+    "content": "{\"name\": \"Updated Demo Channel\", \"about\": \"Updating a test channel.\", \"picture\": \"https://placekitten.com/201/201\"}",
+    "tags": [["e", <channel_create_event_id> <relay-url>]],
+    ...
+}
+```
+
+
+## Kind 42: Create channel message
+
+Send a text message to a channel.
+
+Clients SHOULD use [NIP-10](10.md) marked "e" tags to recommend a relay and specify whether it is a reply or root message.
+
+Clients SHOULD append [NIP-10](10.md) "p" tags to replies.
+
+Root message:
+
+```json
+{
+    "content": <string>,
+    "tags": [["e", <kind_40_event_id> <relay-url> "root"]],
+    ...
+}
+```
+
+Reply to another message:
+
+```json
+{
+    "content": <string>,
+    "tags": [
+        ["e", <kind_42_event_id> <relay-url> "reply"],
+        ["p", <pubkey> <relay-url>],
+        ...
+    ],
+    ...
+}
+```
+
+
+## Kind 43: Hide message
+
+User no longer wants to see a certain message.
+
+The `content` may optionally include metadata such as a `reason`.
+
+Clients SHOULD hide event 42s shown to a given user, if there is an event 43 from that user matching the event 42 `id`.
+
+Clients MAY hide event 42s for other users other than the user who sent the event 43.
+
+(For example, if three users 'hide' an event giving a reason that includes the word 'pornography', a Nostr client that is an iOS app may choose to hide that message for all iOS clients.)
+
+```json
+{
+    "content": "{\"reason\": \"Dick pic\"}",
+    "tags": [["e", <kind_42_event_id>]],
+    ...
+}
+```
+
+## Kind 44: Mute user
+
+User no longer wants to see messages from another user.
+
+The `content` may optionally include metadata such as a `reason`.
+
+Clients SHOULD hide event 42s shown to a given user, if there is an event 44 from that user matching the event 42 `pubkey`.
+
+Clients MAY hide event 42s for users other than the user who sent the event 44.
+
+```json
+{
+    "content": "{\"reason\": \"Posting dick pics\"}",
+    "tags": [["p", <pubkey>]],
+    ...
+}
+```
+
+## NIP-10 relay recommendations
+
+For [NIP-10](10.md) relay recommendations, clients generally SHOULD use the relay URL of the original (oldest) kind 40 event.
+
+Clients MAY recommend any relay URL. For example, if a relay hosting the original kind 40 event for a channel goes offline, clients could instead fetch channel data from a backup relay, or a relay that clients trust more than the original relay.
+
+
+Future extensibility
+--------------------
+
+We reserve event kinds 45-49 for other events related to chat, to potentially include new types of media (photo/video), moderation, or support of private or group messaging.
+
+
+Motivation
+----------
+If we're solving censorship-resistant communication for social media, we may as well solve it also for Telegram-style messaging.
+
+We can bring the global conversation out from walled gardens into a true public square open to all.
+
+
+Additional info
+---------------
+
+- [Chat demo PR with fiatjaf+jb55 comments](https://github.com/ArcadeCity/arcade/pull/28)
+- [Conversation about NIP16](https://t.me/nostr_protocol/29566)