I wonder if the “spawn” API is ever preferable over “fork”. Do we really want to remove context if we can help it? There will certainly be situations where we have to, but then what you want is good compaction for the subagent. “Clean-slate” compaction seems like it would always be suboptimal.

context rot and bias removal would be two good reasons to start a freshly spawned agent.

This is my question also but a bit different.

Is there any reason to explicitly have this binary decision.

Instead of single primitive where the parent dynamically defines the childs context. Naturally resulting in either spawn or fork or anything in between.