What was done
Saffron-codes used Claude Code to work out the Bluetooth LE protocol of a Blue Star split AC and built CoolBar, a tray app for Linux and Windows plus an Android app. Every control was checked on the real unit.
CoolBar is an open-source controller for the Blue Star BI-IC318VNUS split air conditioner. It talks to the unit directly over Bluetooth LE, with no Wi-Fi setup and no cloud account. The commits are co-authored by Claude, and the author says the whole thing was built in a day with Claude Code.
How it was done
The AC has an Espressif ESP32 module and uses the open BluFi transport. The author reverse engineered the command protocol by watching how the unit and its official app talk, only to work with hardware he owns. The README documents the message types, the pairing step and how each remote function maps to a setting. Commands are JSON sent over BluFi after an encrypted key negotiation, and the unit pushes its status back about every three seconds.
The repo has a read-only probe, a pairing probe and a verify script. The verify script sends a change, waits for the AC's own status message, checks the value came back, then restores the old value.
Results
The README says the tray panel, pairing and control all work, and that every remote function was verified on the unit. The repo also builds an Android app, a Windows zip and a Linux installer through tagged releases. It contains no code from the vendor and is released under the MIT licence.
