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Claude Code 2.1.221 and 2.1.222 Harden the Agent Boundary: SendMessage Now Runs Through the Permission Classifier and Sandbox Credentials Are Masked on Linux/WSL
Anthropic shipped Claude Code 2.1.221 on August 4 and 2.1.222 on August 5, 2026. The security-relevant changes are that messages sent to other agent sessions via SendMessage are now evaluated by the permission classifier — closing an agent-to-agent path that previously bypassed it — plus sandbox credential masking on Linux/WSL, stronger worktree isolation and safer auto-allow handling. Quality-of-life additions include a VSCode Focus view on Ctrl+Alt+F, session-to-PR linking, faster Windows startup and screen reader accessibility fixes. Separately on August 1, the Claude Developer Platform extended the Dreams research preview to Claude Opus 5.
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