diff --git a/docs/abra/hack.md b/docs/abra/hack.md
index f5c3a21..64147b9 100644
--- a/docs/abra/hack.md
+++ b/docs/abra/hack.md
@@ -2,6 +2,19 @@
 title: Hack
 ---
 
+## Contributing
+
+Welcome to Hacking the Planet with `abra`! We're looking forward to see what
+you come up. If you have any questions, don't hesitate to ask 💖 If any of your
+changes seems a bit controversial, it's probably to come have a chat first to
+avoid heartache.
+
+In general, we're into the idea of "Optimistic Merging" (instead of
+"Pessimistic Merging" based on our understanding of
+[C4](https://hintjens.gitbooks.io/social-architecture/content/chapter4.html)
+(described further down under "Development Process" and also [in this blog
+post](http://hintjens.com/blog:106)).
+
 ## Quick start
 
 Get a fresh copy of the `abra` source code from [here](https://git.coopcloud.tech/coop-cloud/abra).