feat: issue free tickets without minting an invoice

Free events (price_per_ticket == 0) tried to mint a 0-amount Lightning
invoice via create_payment_request — an invoice that can't settle, and
which the invoice listener would never mark paid, so the ticket never
became scannable.

api_ticket_create now short-circuits when the final charge is 0 (a free
event or a 100%-off promo, computed after promo + quantity) before any
invoice / fiat-provider logic: _issue_free_tickets creates the N rows and
runs each through the existing set_ticket_paid — the same path
on_invoice_paid drives for a settled payment (flip paid, bump
sold/available under the per-event lock, republish the NIP-52 event) —
plus the ticket notification. The response carries a new
TicketPaymentRequest.paid=True with no payment_request so the client
skips the QR / payment-poll and goes straight to the ticket QRs.

No invoice means sats_paid=0, so free tickets are naturally skipped by
refund_tickets. All rows in a batch share one synthetic payment_hash —
the join key the poll / WebSocket / My-Tickets lookups use — mirroring
the paid multi-ticket path.

Self-service forfeit (#28), abuse/identity limits (#29) and
pay-what-you-want/donation tickets (#30) are tracked as follow-ups.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

models.py

@@ -183,6 +183,10 @@ class TicketPaymentRequest(BaseModel):
     fiat_payment_request: str | None = None
     fiat_provider: str | None = None
     is_fiat: bool = False
+    # True when the tickets are already issued + paid with no invoice to
+    # settle — free events (price 0) or a 100%-off promo. The client skips
+    # the QR / payment-poll step and goes straight to the ticket QRs.
+    paid: bool = False
     # Row ids created on this invoice — one for single-ticket
     # purchases, N for multi-ticket (each independently scannable at
     # the door). Buyers fetch these after payment to render N QRs in

views_api.py

@@ -66,7 +66,12 @@ from .models import (
     TicketPaymentRequest,
 )
 from .nostr_hooks import publish_or_delete_nostr_event
-from .services import refund_tickets, resend_ticket_email_notification
+from .services import (
+    refund_tickets,
+    resend_ticket_email_notification,
+    send_ticket_notification_in_background,
+    set_ticket_paid,
+)
 from .tasks import deregister_payment_listener, register_payment_listener
 
 events_api_router = APIRouter(prefix="/api/v1/events")
@@ -508,6 +513,62 @@ async def api_get_ticket(ticket_id: str) -> Ticket:
     return ticket
 
 
+async def _issue_free_tickets(
+    *,
+    event: Event,
+    quantity: int,
+    name: str | None,
+    email: str | None,
+    user_id: str | None,
+    promo_code: str | None,
+    nostr_identifier: str | None,
+    request: Request,
+) -> TicketPaymentRequest:
+    """Issue `quantity` free tickets without minting an invoice.
+
+    Each row is created then run through `set_ticket_paid` — the exact path
+    `on_invoice_paid` drives for a settled payment: it flips `paid`, bumps
+    the sold / available counters under the per-event lock, and republishes
+    the NIP-52 calendar event so connected clients see the new counts.
+    Notifications fire the same way. No invoice exists, so `sats_paid` is 0
+    and these tickets are naturally skipped by `refund_tickets`.
+
+    All rows in the batch share one synthetic `payment_hash` — the join key
+    the poll / WebSocket / My-Tickets lookups use — mirroring how the paid
+    multi-ticket path shares the real invoice hash.
+    """
+    payment_hash = urlsafe_short_hash()
+    ticket_ids: list[str] = []
+    for _ in range(quantity):
+        row_id = urlsafe_short_hash()
+        ticket = await create_ticket(
+            payment_hash=payment_hash,
+            wallet=event.wallet,
+            event=event.id,
+            name=name,
+            email=email,
+            user_id=user_id,
+            ticket_id=row_id,
+            extra={
+                "applied_promo_code": promo_code,
+                "nostr_identifier": nostr_identifier,
+                "ticket_base_url": str(request.base_url).rstrip("/"),
+                "sats_paid": 0,
+            },
+        )
+        await set_ticket_paid(ticket)
+        send_ticket_notification_in_background(ticket)
+        ticket_ids.append(row_id)
+
+    return TicketPaymentRequest(
+        payment_hash=payment_hash,
+        payment_request=None,
+        is_fiat=False,
+        paid=True,
+        ticket_ids=ticket_ids,
+    )
+
+
 @tickets_api_router.post("/{event_id}")
 async def api_ticket_create(
     event_id: str, data: CreateTicket, request: Request
@@ -571,6 +632,22 @@ async def api_ticket_create(
     # Scale by quantity AFTER the promo applies. One invoice, N tickets.
     price = unit_price * quantity
 
+    # Free tickets (final charge 0 — a free event or a 100%-off promo).
+    # Short-circuit before any invoice / fiat-provider logic: no Lightning
+    # invoice can settle for 0, so we issue the rows and mark them paid
+    # directly. payment_method is irrelevant here (nothing is charged).
+    if price <= 0:
+        return await _issue_free_tickets(
+            event=event,
+            quantity=quantity,
+            name=name,
+            email=email,
+            user_id=user_id,
+            promo_code=promo_code,
+            nostr_identifier=nostr_identifier,
+            request=request,
+        )
+
     if payment_method == "fiat" and not event.allow_fiat:
         raise HTTPException(
             status_code=HTTPStatus.BAD_REQUEST,