Claude Code 2.1.318 backgrounds long subagent commands and warns ten days before a headless sign-in ends

Background subagents now move a shell command to the background after 3 minutes on all providers. The release notes give the reason: the prompt cache should not expire while the command runs. They report no measurements for the change. For claude -p, the release adds a one-line stderr warning starting 10 days before a stored claude.ai sign-in ends, and exposes the end date as loginExpiresAt in claude auth status and as credential_expires_at in claude -p JSON results.

deniedMcpServers URL entries now also block Anthropic-provided servers whose upstream URL matches, and connectors in cloud sessions and on self-hosted runners. The notes say to deny a connector by name otherwise. The same release stops unattended runs (claude -p, SDK apps) from rewriting ~/.claude.json when nothing in it changed, and makes that file, settings files and the stored login less likely to be deleted, briefly emptied or replaced by an older copy on shared network home directories.

Why it matters: If you run scheduled or headless Claude Code jobs, the sign-in end date is now something a script can read ahead of time. And a deny rule written as a URL now covers more than it did, so check your list before the update reaches a runner.