This is all 100% correct, to the best of my understanding. I do not have any special insight into how Disney actually implemented things. I'm an experienced software engineer and based on my observations of how things work, I would bet that the internals are pretty close to this.
I ran a bunch of tests looking at various combinations of overlapping stacked reservations, booking and canceling reservations in different orders, etc., so this is all based on my observations, not other people's reports. Keep in mind that Disney can change this at any time, so this is how it was working last week. Disney has tweaked every version of FastPass at least once or twice, so it's entirely possible some of this may change. Mostly Disney will be analyzing whether there are people hogging too much of the attraction capacity. If that happens, expect Disney to take action.
Anyway, Genie+ is what we call in computer science a "state machine". It's a simple implementation that keeps track of a state or states and simple rules for transitioning between the various states.
In this case there are only two states for each guest: 1) Eligible to book a Genie+ reservation, or 2) Not eligible to book a Genie+ reservation.
There is one (or maybe two) field(s) in a database tracking your status all day.
You begin the day in state 1, "eligible."
When you book a reservation, you go to state 2, "not eligible" and an eligibility time is set for when you'll be eligible
assuming nothing makes you eligible before that point. (Much of the time, something will happen, like tapping into a reservation, and the eligibility time is moot.)
The eligibility time is set like this:
- If the park that the attraction is in is not yet open, eligibility is the earlier of the end of the arrival window and 2 hours after park opening.
- If the park that the attraction is in is open, eligibility is the earlier of the end of the arrival window and 2 hours from the current time.
Examples:
- It's 7:02. Park opens at 9:00
- You book a 9:30-10:30 reservation. Eligibility time: 10:30 (end of arrival window)
- You book a 10:30-11:30 reservation. Eligibility time: 11:00 (2 hours after opening)
- It's 10:02. Park opened at 9:00
- You book a 10:30-11:30 reservation. Eligibility time: 11:30 (end of arrival window)
- You book an 11:30-12:30 reservation. Eligibility time: 12:02 (2 hours from right now)
You can always view your eligibility time by trying to book. If it succeeds, you're eligible now. If it fails, you will either be shown when you will be eligible again, or you'll get a screen with an "Edit" button you can tap to see when you'll be eligible again.
When you tap into a reservation (including during the grace period), you move to state 1, "eligible."
When you cancel a reservation (including during the grace period, though your cancellation grace period seems to be shorter), you move to state 1, "eligible."
When a ride goes down within or just before your arrival window, and you haven't already ridden, you get a multi-attraction pass and you move to state 1, "eligible."
Whenever you become eligible for any reason, the eligibility time is cleared and is no longer relevant.
Now, the implication of all these rules is that you can, in general, wait until the eligibility time arrives, become eligible, book a new reservation, and also tap into or cancel your existing reservation (possibly taking advantage of the grace period), become eligible, and book
another new reservation.
It also implies that once you have two outstanding reservations, you can keep two outstanding reservations for the rest of the day, because every time you tap into or cancel one, you can book another. If you forget, and tap into or cancel two in a row without booking in between, you lose an opportunity to book and now have one fewer reservation outstanding.
What you can't do:
- You can't take advantage of both the 2 hour eligibility rule and the "end of the arrival window" rule for the same reservation. They're the same rule - there's just one eligibility time which is either 2 hours away or at the end of your arrival window.
- You can't take advantage of the eligibility time, book something, and then immediately take advantage of the eligibility time for another overlapping reservation you booked earlier. The system only stores one time, which was set the last time you booked a reservation.
I hope this answers every question, and folks can just point people back to this. At least until Disney changes the rules...
Don