→ A tab is a shell. Split panes, real TTY, job control. Reload and it is still there.
→ Any device. Phone-ready: touch scroll, extra keys, home-screen install, notifications when a command needs you.
→ Somewhere else. Name a connect command — ssh dev-vm, docker exec … — and a tab becomes that machine.
→ Hand it over. Share a session; take control from another device mid-command, or send a watch-only link that can look but never type.
→ Legible to agents. Every command indexed with its exit code and output, over a plain HTTP API.