We recognize that users want to have control over the current start-up behavior of our lights, so we are currently working on a solution to allow our users to choose their start-up light setting. More information will follow soon, so keep an eye on our app updates.— Philips Hue (@tweethue) 12. Januar 2018
The API is explained here:
https://developers.meethue.com/develop/hue-api/supported-devices/Startup object attributes Mode of the startup behavior
safety: lights go back to Philips “bright light” safety setting (100% brightness @ 2700K)
powerfail: light keeps the setting when power failed. If light was off it stays off
lastonstate: light keeps the setting when power failed. If light was off it returns to the last on state
custom: custom settings defined in custom settings. Will be automatically set when providing “customsettings”. Not available for “On/Off Light”configured: true if the startup settings are committed to the device, false if not. If this attribute is not present (<1.28) the bridge does not ensure the settings are committed.