docs(events): guest checkout, fiat return flow and ticket delivery contract

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYwoAkZZmXMMmaBp4WGUBo

docs/02-modules/events-module/guest-checkout.md

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+# Events — guest checkout, fiat return flow and ticket delivery
+
+Buyers can purchase **paid** tickets without an LNbits account. This note is
+the wire contract between the webapp and the `aiolabs/events` extension
+(≥ v1.6.1-aio.8) for that flow. Free tickets still require a login
+(events#29: no anonymous free issuance).
+
+## Identity on `POST /events/api/v1/tickets/{event_id}`
+
+| Buyer | Body fields | Auth header |
+|---|---|---|
+| Logged in | `user_id` + `email` (delivery address, prefilled from the account, editable) | `Authorization: Bearer <token>` |
+| Guest | `name` + `email` | none (the endpoint is anonymous; the instance `X-API-KEY` is always sent) |
+
+Every purchase also sends `frontend_url` — this app's root
+(`window.location.origin + import.meta.env.BASE_URL`, no trailing slash;
+`src/modules/events/lib/frontendRoot.ts`). The extension only accepts it when
+its origin is on the LNbits `LNBITS_CORS_ALLOWED_ORIGINS` allowlist (or the
+LNbits base / custom-frontend origin); otherwise the request fails with
+`frontend_url origin is not allowed.` and the dialog shows that message.
+
+`payment_method` is `lightning` or `fiat`. The event's enabled rails come from
+the NIP-52 tag `tickets_payment_methods` (`"lightning,fiat"`); when the tag is
+absent the legacy rule applies (Lightning always, fiat iff
+`tickets_allow_fiat`). See `lib/paymentMethods.ts`. A rail that is off is
+rejected by the backend with `Payment method not enabled for this event.`
+
+## Return from the fiat provider
+
+The extension composes both Stripe URLs under `frontend_url`:
+
+| Purpose | URL |
+|---|---|
+| success | `<root>/events/{event_id}?checkout=success&tickets=<id1,id2>` |
+| cancel | `<root>/events/{event_id}?checkout=cancelled` |
+
+Before redirecting (same tab, `window.location.assign`), the purchase dialog
+writes `localStorage['events:pending-checkout']` =
+`{ eventId, paymentHash, ticketIds, email, ts }` (`lib/pendingCheckout.ts`).
+`EventDetailPage` strips the query on arrival, then:
+
+- `success` → opens `CheckoutReturnDialog`, which polls the anonymous
+  `GET /events/api/v1/tickets/{ticket_id}` for every id every 2 s (60 s budget,
+  retry button) until all are `paid`, then renders one QR per ticket, the
+  "emailed to" note (email from the localStorage record) and a link to the
+  ticket page. Logged-in buyers also get `useOwnedTickets().refresh()`.
+- `cancelled` → info toast, record cleared. Nothing was charged; the
+  extension purges unpaid rows after 24 h.
+
+## Public ticket page
+
+`/events/ticket/:ticketId` (`views/TicketPage.vue`, `requiresAuth: false`) is
+where the emailed link lands. It reads the `PublicTicket` (no id / email /
+user_id in the payload; the id in the URL is the door credential, exactly as
+in the LNbits UI), resolves the event name (Nostr store → scoped relay query
+→ public REST, which 410s on sold-out events and is treated as non-fatal) and
+renders the QR.
+
+## QR rendering
+
+All `ticket://<id>` QRs (purchase success, return dialog, ticket page, My
+Tickets) go through `lib/ticketQr.ts`: error-correction level H with the
+brand logo (`@brand/logo.png`) centred at ≤ 20 % width on a white pad, so the
+in-app image matches the PNG the extension embeds in the ticket email
+(`GET /events/api/v1/qr/{ticket_id}`). Canvas failures fall back to the plain
+QR.
+
+## Organizer side
+
+`CreateEventDialog` publishes `extra.payment_methods` (Lightning / Card
+checkboxes; at least one) and keeps `allow_fiat` in sync for older readers.
+Card is disabled with a tooltip when the organizer's LNbits user has no fiat
+provider (`useFiatProviders().hasAnyProvider`).
+
+`resendTicketEmail` returns the structured `TicketResendResult`
+(`{ ticket, email: {attempted, sent, error}, nostr: {...} }`).