Running one coding agent is a chat window. Running seven is an operations problem, and nothing existed to manage it.
Hivemind gives every agent its own isolated tmux session and its own process, then puts them in one window: a lead coordinating teammates, a file tree, a git tab showing exactly what changed, and a terminal you can drop into when an agent gets stuck.
What was hard
Output streaming. Seven agents each emitting a terminal stream will saturate an Electron renderer and freeze the UI. The output path is zero-copy with automatic degradation — under load it drops intermediate frames rather than queueing them, so the window stays responsive and you still see the current state.
Process isolation. Agents run with real shell access, so a crashed or misbehaving one must not take the app or its siblings down. Each gets a separate process and a context-isolated security boundary.
Knowing what actually happened. The point of running a team is shipping, and you cannot ship what you cannot review. The git tab is the answer to “what did these seven things do to my repository.”
632 tests. Multi-platform builds for macOS, Windows and Linux through GitHub Actions, with parallel matrices so a three-platform release does not take an afternoon.