Domen Kožar

What happens if you set `subsitituters`?

I agree. Cachix was made before extra-substituters worked properly (they were not appending between configuraitons). Migrating to extra-substituters makes sense now that all recent Nix versions support it properly.

Same happened to @mpickering, a clear message that the key is wrong would be very helpful.

+ number of seconds it took

This can be done by just specifying the agents that should be deployed in JSON. Probably just need a section to explain how it's done.

A flag would still be useful to avoid recreating JSON file.

Since then it prints storage size, do you think that suffices?

This is on high priority list.

Refs #80

That's possible with either #246 or `cachix push --watch-store`.