test: booking-flow, availability, and #4 concurrency regression

16 tests, run under the LNbits pytest env (spirekeeper pattern: monkeypatch
crud/invoice, drive async via asyncio.run — no live DB/wallet):

- test_availability: half-open overlap semantics (back-to-back stays OK),
  and is_available blocking on held/confirmed bookings + manual blocks.
- test_booking_flow: canonical amount_sat, awaiting_payment transition,
  min-nights guard, and hold-release (declined) on InvoiceError.
- test_atomic_hold: the #4 regression — two concurrent same-date requests
  yield exactly one hold + one conflict; non-overlapping both succeed. The
  fakes yield mid-check to open the race window, so the test fails without
  the per-room lock (verified by neutering it) and passes with it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VUQCfdqiLSsFS2jcGnaFD

tests/test_availability.py

@@ -0,0 +1,87 @@
+"""Availability arbiter: half-open overlap semantics + is_available()."""
+
+import asyncio
+
+from .. import crud
+from ..models import Block, Booking, BookingStatus, RoomStatus
+from .conftest import make_room
+
+
+# --- pure interval logic ---------------------------------------------------
+
+
+class TestOverlap:
+    def test_disjoint_ranges_do_not_overlap(self):
+        assert not crud._overlaps("2026-08-01", "2026-08-04", "2026-08-04", "2026-08-06")
+
+    def test_back_to_back_same_day_does_not_overlap(self):
+        # check_out is exclusive: one guest leaves 08-04, next arrives 08-04.
+        assert not crud._overlaps("2026-08-01", "2026-08-04", "2026-08-04", "2026-08-07")
+
+    def test_partial_overlap(self):
+        assert crud._overlaps("2026-08-01", "2026-08-05", "2026-08-04", "2026-08-08")
+
+    def test_full_containment(self):
+        assert crud._overlaps("2026-08-01", "2026-08-10", "2026-08-03", "2026-08-05")
+
+    def test_nights_between(self):
+        assert crud.nights_between("2026-08-01", "2026-08-04") == 3
+
+
+# --- is_available (crud getters monkeypatched) -----------------------------
+
+
+def _patch(monkeypatch, *, room, bookings=None, blocks=None):
+    async def _get_room(_):
+        return room
+
+    async def _get_bookings(_):
+        return bookings or []
+
+    async def _get_blocks(_):
+        return blocks or []
+
+    monkeypatch.setattr(crud, "get_room", _get_room)
+    monkeypatch.setattr(crud, "get_bookings_for_room", _get_bookings)
+    monkeypatch.setattr(crud, "get_blocks_for_room", _get_blocks)
+
+
+def _booking(status: BookingStatus, ci="2026-08-02", co="2026-08-05") -> Booking:
+    return Booking(
+        id="b1", room_id="room1", guest_pubkey="g", check_in=ci, check_out=co,
+        nights=3, num_guests=1, currency="sat", price_fiat=300.0,
+        amount_sat=300, deposit_sat=300, status=status,
+    )
+
+
+class TestIsAvailable:
+    def test_open_range_is_available(self, monkeypatch):
+        _patch(monkeypatch, room=make_room())
+        assert asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))
+
+    def test_inactive_room_is_never_available(self, monkeypatch):
+        _patch(monkeypatch, room=make_room(status=RoomStatus.inactive))
+        assert not asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))
+
+    def test_overlapping_confirmed_booking_blocks(self, monkeypatch):
+        _patch(monkeypatch, room=make_room(),
+               bookings=[_booking(BookingStatus.confirmed)])
+        assert not asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))
+
+    def test_overlapping_held_booking_blocks(self, monkeypatch):
+        # A mere hold occupies the calendar — this is what makes the atomic
+        # check-then-hold work.
+        _patch(monkeypatch, room=make_room(),
+               bookings=[_booking(BookingStatus.held)])
+        assert not asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))
+
+    def test_cancelled_booking_does_not_block(self, monkeypatch):
+        _patch(monkeypatch, room=make_room(),
+               bookings=[_booking(BookingStatus.cancelled)])
+        assert asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))
+
+    def test_manual_block_blocks(self, monkeypatch):
+        blk = Block(id="k1", room_id="room1", start_date="2026-08-03",
+                    end_date="2026-08-06", reason="maintenance")
+        _patch(monkeypatch, room=make_room(), blocks=[blk])
+        assert not asyncio.run(crud.is_available("room1", "2026-08-01", "2026-08-04"))