RobotDancers

BeatBot makes a UFactory xArm 7-DOF dance to whatever song you throw at it. Librosa picks the beats offline, and the arm runs through a small bank of joint poses on every beat, with safety baked in so it never whips itself around: per-joint angle envelopes, slow speed and accel caps, and a beat-rate throttle for fast songs. A webcam records the run, ffmpeg muxes the song audio into the video, and the whole take pushes back to the repo for review. What made this different was the build loop. Most of what's been shown with Opus 4.7 is webapps and agents. We pointed it at a real 7-DOF arm with real torque, on hardware we already use for vision research. Claude wrote the choreography, the safety clamps, the beat scheduler, the camera fallback, and the SIGINT handling. It read our existing visual_servoing repo to match conventions, remembered the lab IP and conda env across turns, and when something broke on the robot we just pushed the log and the recorded video back to the repo. Claude pulled them and diagnosed directly from the artifacts, including a subtle threading bug where Ctrl-C wasn't unwinding the xArm's blocking calls.