[WIP] MSC3868: Room Contribution

proposals/3868-room-contribution.md

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+# MSC3868: Room Contribution
+
+Many projects and communities have a room on Matrix nowadays and many may wish to show their friends how to support
+them.
+The goal, would be to have something only visible to room & space members and to provide something easier to manage &
+display than putting links into the room topic or announcing them periodically.
+
+## Proposal
+
+This proposal implements a new `m.room.contribute` state event. This state event contains a "uri" parameter that may
+link to a git repo or any kind of URI and a "text" parameter that may contain the text of the button directing to the
+support link. There may be multiple "uri" and "text" parameters, each adding a different button containing a different
+link. Alternatively to the "uri" parameter, a "copy" one can be specified and will tell clients to copy the value in
+the clipboard. Another, optional, "badge_uri" parameter may be specified and only may contain a MXC URI to a image
+media. When specified, the image, or badge, is displayed in place of the text, the text becoming the `alt` property
+of said image.
+An example of this event would look like this:
+
+```json
+{
+  "links": [
+    {
+      "uri": "https://git.me/contribute",
+      "text": "Contribute code!"
+    },
+    {
+      "uri": "https://translate.me/contribute",
+      "text": "Translate the project!"
+    },
+    {
+      "uri": "mailto:team@verygoodproje.ct",
+      "text": "Get in touch!"
+    },
+    {
+      "text": "Donation IBAN",
+      "copy": "CH5604835012345678009"
+    },
+    {
+      "uri": "https://liberapay.com/foo",
+      "text": "Support us on LiberaPay",
+      "badge_uri": "mxc://jae.fi/5d718eb34d05c8b6b1304e2a106aa800400476a6"
+    }
+  ]
+}
+```
+
+## Potential issues
+
+The authors aren't aware of any potential issues being raised.
+
+## Alternatives
+
+Historically, that sort of advertisement is either taken care of by adding the said URIs to the room topic or
+periodically sending an announcement in the channel. However room topic is public information when the room
+has `m.room.join_rules` other than `invite`.
+
+## Security considerations
+
+State events are currently not encrypted which could leak some data.
+
+## Unstable prefix
+
+Unstable implementations should use the state event type of `eu.dn0.msc3868.rev1.room.contribute`
+
+## Dependencies
+
+The authors believe this MSC could benefit from
+[MSC3414: Encrypted State Events](https://github.com/matrix-org/matrix-spec-proposals/pull/3414)
+while not considering it as a blocker.
+Given the use of MXC URIs to display badges, the implementation of
+[MSC3468: MXC to Hashes](https://github.com/matrix-org/matrix-spec-proposals/pull/3468)
+would benefit the current MSC while, again, not blocking its implementation.