I agree, Claude does spawn subagents but subagents don't spawn sub-subagents.

Are you sure? In Opencode they can, but it's hard to track them then (say, if you want to steer them) -- you have to click through. It would be nice to have a dynamic execution graph alongside the text.

This is the comment I was looking for. In the last month or so this is how Claude Code represents tasks, as a DAG of objectives, built from plan mode.

Yeah exactly. I noticed Claude start doing exactly this a month ago too. It recursively breaks problems down while allowing you to either change direction at each level or keep going. This is where claude jumped up to be legitimately better at solving real world problems than a substantial amount of developers. I can only assume the other AI companies are just going to copy the approach shortly too.