Claude Code (subscription) has Agent Teams built in. Teams of Agents communicate with local files that they use as inboxes and task list. Has tmux and iTerm 2 integration.
https://code.claude.com/docs/en/agent-teams
They can rack up some extra tokens if you leave agents going idle. Because they loop, checking for new messages for them.
Using Claude Channels can make it easy to inject prompts and get just the response back without having to identify it in the terminal output or fight with the TUI.
But they're not well designed, and some things just have to go in through the terminal interface like slash commands (i.e. `/clear`)
The law of Software Envelopment. Jamie Zawinski in 1995 stated that "software inevitably expands to include email functionality, or it is replaced by software that does"
Clearly, that's not the case anymore. Nowadays you just swap out "email" for "LLM"