Unclear Where the subagent cap's value comes from, and whether it always applies, is not known.
What
When a shell command runs too long, Claude Code moves it to the background so the conversation can continue. A subagent is a helper agent Claude starts to work on part of a task.
- Subagent cap: the auto-background timeout now takes a
subagentCapMsvalue and applies to subagents as well. Before, only the main agent honouredCLAUDE_CODE_AUTO_BACKGROUND_TIMEOUT_MS. Bash and PowerShell results carry a newsubagentCapAppliedfield, true when this cap shortened a command's timeout. - Backgrounding message: the message now says "It is running now: do not start a second copy while it runs", explains how to stop it, and warns that buffered output can leave the output file empty. When the subagent cap applied, it says the command was moved to the background after running for a number of seconds, instead of citing a timeout.
- Output seen: the message also reports whether any output was seen before the timeout (
noOutputSeenAtTimeout). - Stop reasons: a stopped background command's message can now use an optional
stopExplanationinstead of the fixed stop text. A stop at a deadline gets one. - PowerShell: it passes the subagent cap and forwards progress only under a condition.
Why
Long commands run by subagents can move to the background earlier. Claude is told not to launch duplicate copies, such as a second server, and not to read an empty output file as a failure.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
Where the subagent cap's value comes from, and whether it always applies, is not known.