Message finishes_at from a timer

1

my first post and new to HA! i’m trying to do the simplest thing I don’t understand why this is so difficult.

I have a timer.dishwasher_timer helper. All i want to do is create an automation to use the notify.notify service to message me with an ETA time on when the dishwasher is gonna be done or use the timer’s finishes_at function.

here is what i’m starting but i get nothing useful. any idea?

alias: Timer Notifications
description: ''
trigger:
  - platform: event
    event_type: timer.started
    event_data:
      entity_id: timer.dishwasher_timer
condition: []
action:
  - variables:
      f: state_attr('timer.dishwasher_timer', 'finishes_at')

  - service: notify.notify
    data:
      message: >-
        (as_datetime(f) - now()).total_seconds() | timestamp_custom('%H:%M:%S',
        false) }}
mode: single