By Aug, confirm the Shelly Dimmer Gen4 stayed stable on ZHA for about a month. If stable, move it from the extension-cord test setup into the intended in-wall light circuit with two physical switches / alternating switch wiring. With the final fixture/load connected, run formal calibration before closing everything up. Then verify: both physical switches, HA/ZHA on/off + dimming, stability, and no exposed wiring. If Wi-Fi/Shelly UI must be restored for calibration/settings, disable Wi-Fi again afterward and confirm ZHA still works.