Chromecast Voice Timer

Hi

i have a Google Voice Kit Integrated with Openhab thanks to IFTTT.

my goal is simple to say to my voicekit “alarm in X minutes to #make this#”

Thanks to ifttt, it will send a command to an openhab item.

it should create a timer based on the output.

Once the timer is finished, it should say “Time is up to make this” through chromecast audio

to create the timer, it’s ok

to say with the chromecast, it’s ok

My concern is how to strip the input

Thanks for your help