Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
Background AgentsArea: what it touches
Internal ChangesKind: in v2.1.311,
Internal ChangesSection of the release
What
A sub-agent is a separate helper Claude starts to work on part of a task, sometimes in the background. Claude Code writes short summaries of what such an agent is doing. These summaries used to be made on a fixed timer. Now a summary can be held while the sub-agent's own request has not had a response yet and its prompt cache is likely cold. The prompt cache is stored earlier context that makes repeat requests cheaper and faster, and cold means it is not ready yet. The check repeats until a maximum hold time passes.
The summary also forgets its previous text if the next request would be missing a message the earlier summary was based on.
Why
This avoids extra requests that waste the cache, and stops summaries from building on text that no longer matches the conversation.
