What changed
Claude Code 2.1.319 moves MCP task tool calls to the background, adds permissions.denyInsteadOfPrompting so unattended tools can fail instead of waiting, and changes auto-mode behavior when server checks are unavailable. It also adds gateway spend, pooled-budget, JSON-log and policy warnings.
Why it matters
The release changes how unattended work progresses and fails: background tasks reduce blocking, while hard denial and a nonzero headless exit when safety checks are unavailable make policy failure visible to automation.
What to do
Canary 2.1.319 with a long MCP task, a denied tool, an unavailable safety check and a gateway budget conflict. Verify task completion delivery, nonzero failure, policy precedence, JSON logs and rollback before enabling unattended sessions.
Caveat
Anthropic's immutable release notes are vendor evidence. Background completion can arrive after surrounding state changes, hard denial can break workflows that relied on prompting, and gateway or provider behavior varies by configuration.