My registration — /r/{ulid}?sig=

Who opens it: somebody who registered days or weeks ago, from a link in their confirmation email.

What they came to do: one of three small things — check what they signed up for, fix something that is wrong (a misspelled name, a new phone number), or say that one person can no longer come.

True when they leave: the record matches reality, or they know who to ask. They never end up in a state where a ticket they are carrying no longer works without being told so.

Decisions already made

• The link is signed: a ulid identifies a registration but proves nothing about who holds it.
• Editing updates the people already there and never adds or removes anybody — a dependent may hold an issued ticket whose code cannot change (I4) and which others' admission points at (I3). Adding someone is a conversation with an organizer, and the page says so.
• Attendee type, group and days are not editable here: they decide price, admission and who somebody is counted under, and a day change voids and reissues tickets.
• Cancelling one person voids their live tickets and gives the place back (the meter follows the status). The person whose shared ticket admits the others: the ticket goes to another adult of the right type in the household if there is one; otherwise it is refused, in words (cancel the children first, or ask the organizers).
• "Someone else is coming" hands one person's place to a named new person before the event starts (week 10): same type, days and household, their tickets reissued with new codes, the old codes void. It replaces one person with one person; it still never adds anybody.
• Edits close at event.settings.self_service_window_closes_offset_minutes — three days before, in the IV Day event template. After that the page still shows everything and says changes are closed.
• Answers validate against the form version they were answered on (I13), so editing cannot validate differently from registering.

Open questions

• Cancelling is free today. Should a paid registration offer a refund, or say "contact the organizer"? (Refund rules are deliberately not wired: a refund does not cancel anything yet, and a cancellation does not refund.)
• Should a cancelled person be removable from the page entirely, or stay struck through as a record?
• Add-to-calendar gives one .ics for the whole registration. Per person would be more correct and more clutter.