Build things that improve after more people become capable of contributing.

Some things get worse as more people touch them and some get better, and the difference is usually designed in from the start. Clear structure, obvious entry points, and a shape that does not depend on any one person’s private knowledge mean each new contributor adds rather than complicates. Without that, growth just multiplies confusion.

Ask of whatever you are building whether a capable newcomer could improve it without asking you first. If the honest answer is no, the bottleneck is not their ability. It is something you have not yet made visible.