fix(cost): widen reservation sweep to hourly so Neon can auto-suspend

src/WidgetWorks.Application/Checkout/ReleaseStale/ReleaseStaleReservationsHandler.cs

@@ -14,13 +14,23 @@ public sealed class ReservationOptions
     ///
     /// This is a trade, not a tuning knob: too short and a slow but honest bank redirect loses a
     /// customer's basket; too long and abandoned or abusive orders hold the catalogue hostage.
-    /// Fifteen minutes is longer than any interactive redirect and short enough that a shopper who
-    /// returns to an out-of-stock item is rare.
+    ///
+    /// Held at 90 minutes so it stays longer than the sweep interval below (the sweep must run more
+    /// often than the window, or expired orders sit unreleased). The interval is set for cost — see
+    /// there — and on this demo deployment no real inventory is at stake, so the longer hold is
+    /// harmless. A production store with scarce stock should shorten both together, or move to
+    /// on-access release, rather than shorten this alone.
     /// </summary>
-    public int ExpireAfterMinutes { get; set; } = 15;
+    public int ExpireAfterMinutes { get; set; } = 90;
 
-    /// <summary>How often the sweep runs.</summary>
-    public int SweepIntervalMinutes { get; set; } = 5;
+    /// <summary>
+    /// How often the sweep runs. Held at 60 minutes on purpose: the sweep queries Postgres each
+    /// tick, and Neon's serverless compute auto-suspends after ~5 minutes idle, so a shorter
+    /// interval pins the database awake around the clock (~180 CU-hrs/month, nearly double the free
+    /// allowance). Hourly lets Neon sleep between passes (~15 CU-hrs/month) while still reclaiming
+    /// abandoned-checkout stock well within the window above. Must stay below ExpireAfterMinutes.
+    /// </summary>
+    public int SweepIntervalMinutes { get; set; } = 60;
 
     /// <summary>
     /// Most orders released in one pass. A backlog is worked through over several sweeps rather

src/WidgetWorks.WebApi/appsettings.json

@@ -36,8 +36,8 @@
   },
   "Reservations": {
     "Enabled": true,
-    "ExpireAfterMinutes": 15,
-    "SweepIntervalMinutes": 5,
+    "ExpireAfterMinutes": 90,
+    "SweepIntervalMinutes": 60,
     "BatchSize": 100
   }
 }

tests/WidgetWorks.UnitTests/ConcurrentSettlementTests.cs

@@ -140,7 +140,9 @@ public async Task ReleaseStaleReservations_AWebhookSettlesAnOrderMidSweep_Counts
             h.Orders,
             (inner, _) => inner.MarkPaidAsync(settled.Id, "Mock", "pi_settled", Now, CancellationToken.None));
         var handler = new ReleaseStaleReservationsHandler(
-            raced, new FakeTimeProvider(Now), new ReservationOptions(), NullLogger<ReleaseStaleReservationsHandler>.Instance);
+            // Explicit 15-minute window so the ~30/40-min-old orders above stay sweepable
+            // regardless of the production default (tuned longer for Neon cost).
+            raced, new FakeTimeProvider(Now), new ReservationOptions { ExpireAfterMinutes = 15, SweepIntervalMinutes = 5 }, NullLogger<ReleaseStaleReservationsHandler>.Instance);
 
         Assert.Equal(5, h.Widgets.Store[h.WidgetId].QuantityReserved);
 

tests/WidgetWorks.UnitTests/ReleaseStaleReservationsTests.cs

@@ -41,7 +41,9 @@ private static Harness Build(ReservationOptions? options = null)
         var handler = new ReleaseStaleReservationsHandler(
             orders,
             new FakeTimeProvider(Now),
-            options ?? new ReservationOptions(),
+            // Explicit 15-minute window so these behaviour tests stay fixed to the offsets they set
+            // (orders parked ~30 min ago), independent of the production default tuned for Neon cost.
+            options ?? new ReservationOptions { ExpireAfterMinutes = 15, SweepIntervalMinutes = 5 },
             NullLogger<ReleaseStaleReservationsHandler>.Instance);
 
         return new Harness(orders, widgets, handler, widgetId);
@@ -135,7 +137,7 @@ public async Task A_sweep_is_safe_to_run_twice()
     [Fact]
     public async Task One_pass_takes_no_more_than_the_batch_size()
     {
-        var h = Build(new ReservationOptions { BatchSize = 2 });
+        var h = Build(new ReservationOptions { BatchSize = 2, ExpireAfterMinutes = 15, SweepIntervalMinutes = 5 });
         for (var i = 0; i < 5; i++)
         {
             await GivenUnsettledOrder(h, quantity: 1, updatedAt: Now.AddMinutes(-30 - i));
@@ -151,7 +153,7 @@ public async Task One_pass_takes_no_more_than_the_batch_size()
     [Fact]
     public async Task The_oldest_unsettled_orders_are_released_first()
     {
-        var h = Build(new ReservationOptions { BatchSize = 1 });
+        var h = Build(new ReservationOptions { BatchSize = 1, ExpireAfterMinutes = 15, SweepIntervalMinutes = 5 });
         var oldest = await GivenUnsettledOrder(h, quantity: 1, updatedAt: Now.AddHours(-3));
         await GivenUnsettledOrder(h, quantity: 1, updatedAt: Now.AddMinutes(-20));