Maybe they’re not “hard” to build, but some are sufficiently complex because they’re tailored to a model. If Z thinks their harness can improve on GLM’s shortcomings, that can give them a tiny edge, I guess?

Dunno. I’ve moved to Pi for most of my work and it’s finally better than Claude Code for me; BUT the Anthropic models are definitely better in CC itself.

I was thinking the same and I changed my mind.

Also you don't need to believe me. There is enough evidence in the open source space.