core: link notices

docs/protocol/simplex-chat.md

@@ -254,11 +254,11 @@ Currently members can have one of four roles - `owner`, `admin`, `member` and `o
 
 `x.grp.mem.con` message is sent by members connecting inside group to inviting member, to notify the inviting member they have completed the connection and no longer require forwarding messages between them.
 
-`x.grp.mem.del` message is sent to delete a member - it is sent to all members by the member who deletes the member referenced in this message. This message MUST only be sent by members with `admin` or `owner` role. Receiving clients MUST ignore this message if it is received from member with `member` role.
+`x.grp.mem.del` message is sent to delete a member - it is sent to all members by the member who deletes the member referenced in this message. This message MUST only be sent by members with `admin` or `owner` role. Receiving clients MUST ignore this message if it is received from member with `member` role. The client of the deleted member applies optional `notice` property to the group link (see [Link notices](#link-notices)).
 
 `x.grp.leave` message is sent to all members by the member leaving the group. If the only group `owner` leaves the group, it will not be possible to delete it with `x.grp.del` message - but all members can still leave the group with `x.grp.leave` message and then delete a local copy of the group.
 
-`x.grp.del` message is sent to all members by the member who deletes the group. Clients who received this message SHOULD keep a local copy of the deleted group, until it is deleted by the user. This message MUST only be sent by members with `owner` role. Receiving clients MUST ignore this message if it is received from member other than with `owner` role.
+`x.grp.del` message is sent to all members by the member who deletes the group. Clients who received this message SHOULD keep a local copy of the deleted group, until it is deleted by the user. This message MUST only be sent by members with `owner` role. Receiving clients MUST ignore this message if it is received from member other than with `owner` role. Receiving clients apply optional `notice` property to the business address of a deleted business chat (see [Link notices](#link-notices)).
 
 `x.grp.info` message is sent to all members by the member who updated group profile. Only group owners can update group profiles. Clients MAY implement some conflict resolution strategy - it is currently not implemented by SimpleX Chat client. This message MUST only be sent by members with `owner` role. Receiving clients MUST ignore this message if it is received from member other than with `owner` role.
 
@@ -266,6 +266,12 @@ Currently members can have one of four roles - `owner`, `admin`, `member` and `o
 
 `x.grp.msg.forward` message is sent by inviting member to forward messages between introduced members, while they are connecting.
 
+### Link notices
+
+`x.grp.mem.del`, `x.grp.del` and `x.direct.del` messages MAY include `notice` property with optional `ttl` (seconds) and optional `reason` (`spam`, `content`, `community`, `profile` or `other`). The receiving client stores the notice for the link it joined or connected through, as recorded in its own group or contact record, and does not connect via this link until the notice expires. The notice expires `ttl` seconds after the server timestamp of the message; a notice without `ttl` does not expire. A new notice for the same link replaces the previous one. Clients MUST ignore a malformed notice and process the message.
+
+When `x.direct.del` message has `"silent": true` property, the receiving client stores the notice and does not delete the contact. Clients send it when the contact is deleted without notification, only to contacts with chat protocol version 21 or later.
+
 ### Channels: relay-mediated groups
 
 Channels are groups where message delivery is mediated by dedicated relay members rather than by direct connections between all members. Channels extend the group sub-protocol with additional roles (`relay`, `observer`), message signing for administrative actions, a binary batch format for signed and forwarded messages, and an asynchronous delivery pipeline.