Claude Code can run background workers, sessions that keep going without a terminal open, and it regularly clears out ones that have finished. Before, that cleanup retired finished workers by its normal rules. Now a worker held on its gateway is kept even when the Claude Code build it runs on has been deleted. The log records the reason as kept on its gateway because its build was deleted.
Background sessions on a gateway are not lost when an upgrade removes the build they were started with.
tengu_bg_prewarm_per_sweep Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.319: not a boolean we can read
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 v2.1.319. It isn't a statement about your account. What a flag value here can and cannot tell you