ATune: Heart Rate and Game Sounds in Your Terminal

Takeaways

• Being pulled out of flow can cost about 20 minutes, so he built ATune, a Rust app that reads ECG from a Polar H10 heart rate monitor over Bluetooth at 130 Hz alongside his coding terminal.
• It windows the ECG around each alert sound and scores whether he oriented back to the task or startled; in his data a Zelda sound calmed him and a Duke Nukem sound did not.
• It turns those scores into a reward function and keeps tuning its sound choices: sounds compete in leagues like a bracket, and a recency decay shows that a sound's calming effect fades.
• The idea comes from the HarnessX paper on self-improving harnesses, which he heard about in a talk by Esteban Puerta at Antler.
• Data stays local, with a Qwen3.5 27B model on his machine doing private digestion and Claude and Codex checking each other; the terminal is herdr, a front end for tmux.