If you use Claude Code regularly, you know the rhythm: type a prompt, hit enter, then wait 10 to 60 seconds while it thinks. Most of us fill that gap by checking Slack, scrolling feeds, or losing focus entirely. MindfulClaude takes a different approach and fills those dead seconds with guided breathing exercises.
The tool is dead simple. It hooks into Claude Code's lifecycle events so that when Claude starts processing, a tmux pane automatically appears with a breathing exercise. When Claude finishes, the pane disappears. No manual toggling, no app switching. The breathing patterns are designed to improve heart rate variability (HRV), which research has linked to better focus and lower stress responses.
It is a clever use of Claude Code's hook system, which lets developers run arbitrary commands when specific events fire. In this case, the "thinking started" and "thinking finished" hooks trigger the breathing UI in a side pane. You need tmux running for the split-pane setup to work, which means this is squarely aimed at terminal-first developers who already live in multiplexed sessions.
The practical value here is less about the breathing itself and more about breaking the context-switching habit. Every time you alt-tab to Twitter during a 30-second wait, you are paying a cognitive tax to re-engage when the result comes back. A breathing exercise keeps your attention loosely anchored to the terminal. That is genuinely useful during long coding sessions where Claude might think dozens of times per hour.
MindfulClaude is available on GitHub as an open-source project. Setup requires tmux and a working Claude Code installation with hooks enabled.