This post is written by the maintainers of cornercase. It's our own project, it's free and open source (MIT or Apache-2.0), and there's nothing paid behind it. We'd like to explain what it does, how it works, and where it still falls short.

The problem

Starting ten coding agents is easy. Keeping up with them is the hard part.

Once you have a few Claude Code or Codex sessions open at the same time, the questions pile up. Which one is waiting for an answer? Which one finished while you were looking at another? What did each one change? Did two of them edit the same file?

We kept answering those questions with tmux, git worktrees and a growing pile of scripts, and we kept re-wiring that setup. cornercase is the tool we built so we could stop.

What cornercase does

cornercase is a terminal multiplexer, in the same family as tmux or Zellij, built around running agents in parallel. It runs inside the terminal you already use.

From an issue to an agent at work.…