❯ Claude Code adds cross-session messaging, letting sessions update each other on progress

CROSS-SESSIONAnthropic has added cross-session messaging to Claude Code: starting with v2.1.224, separate sessions running on macOS and Linux can message one another, syncing discoveries and progress without having to re-explain context from scratch.

SCOPEWhat gets passed is a summary, not conversation history or files, and the recipient can read it while the task is still running. Official example scenarios include handing off a discovery, coordinating parallel git worktrees, checking status on long-running tasks, and replying from another machine. In April this year, Anthropic rebuilt the Claude Code desktop app around parallel sessions and launched repeatable routines the same month; this adds a communication layer on top of that parallel setup. Permission approval requests and configuration changes do not go through this channel.

PARALLELThis turns “opening several windows” into a small team that can keep each other informed. Developers running three or four sessions at once can now split tasks even finer — if tasks can be split and still stay in sync, parallelism actually saves time. It also sets the next competitive battleground: how context flows between multiple agents matters more for real-world efficiency than how large a single session window can grow.

▪ SIGNALThe first step in agent collaboration is getting them to talk to one another.