Seven in the morning.
The cleaner opens the app: two visits today, the first a fortnightly clean at a flat where the access note says the key is in the lockbox and the alarm is off on Thursdays.
She taps on the way; the customer gets a message.
She checks in at the door, the time and location are recorded, and the visit checklist for that plan shows the extras added this week: inside the oven.
Meanwhile the office sees that the regular cleaner for an afternoon visit has reported sick.
The substitution rule offers the customer a named alternative who is free and has a profile the customer can see; the customer accepts from the message and the access note moves to the substitute for that visit only.