Unclear Whether the server switch controls this behaviour or something else is unclear.
Subagents are helper agents Claude starts to work on part of a task. A foreground subagent holds up the conversation until it finishes. With CLAUDE_AUTO_BACKGROUND_TASKS set, Claude Code now moves running foreground subagents to the background when you have a queued message waiting to be sent next.
A related server switch, tengu_valiant_crescent, has a built-in fallback of off, and read off for this site's account in an earlier release.
Your queued message no longer has to wait behind a long-running subagent.
tengu_valiant_crescent Off in both readingsThe flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.
This account: off · anonymous baseline: off · compiled default in v2.1.290: off
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Read once, for one account on one subscription tier, against v2.1.290. It isn't a statement about your account. What a flag value here can and cannot tell you
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
* Fixed `CLAUDE_AUTO_BACKGROUND_TASKS` moving a subagent to the background while an edit or shell command waited behind it, which started that call before the subagent finishedchangelog see the edit
Whether the server switch controls this behaviour or something else is unclear.
Anthropic's documentation has since written up CLAUDE_AUTO_BACKGROUND_TASKS, on Claude Code changelog.
New in this build: tengu_valiant_crescent