I’d be extremely surprised if most Core code (inc. Core Plugins) was not now built with Coding Agents, such is the extent to which development has changed.
It is also clear a lot of effort has been put into the Discourse repo to make it coding agent friendly, both for building extensions and modifying core.
It is now, imho, very hard to justify not using coding agents on most work as the drop in efficiency simply wouldn’t make business or even common sense.
This horse has truly bolted (in fact it bolted around September 2025)
It’s only about standards and workflow refinement now.
You might be better off asking for a tag for “no AI was used to build this” aka “ai-free” as that would apply to so very few.
I get the sensitivity around this, but I really believe the world has moved on.