You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
SubagentsArea: what it touches
ImprovementsKind: in v2.1.227,
ImprovementsSection of the release
What
The guidance for launching a subagent used to say run it in the foreground whenever you need the result before proceeding. It now limits that to cases where the very next action depends on the result and nothing else could usefully happen in the meantime, and names fire-and-forget work and independent investigations as background cases.
Evidence
Wanting the result "next" is not enough on its own.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.