fix(centralui): pending-updates rail refreshes as soon as a deployment finishes — cache drops its snapshot on Success/Failed and signals the indicator, instead of serving the pre-deploy count for up to TTL + one poll

tests/ZB.MOM.WW.ScadaBridge.CentralUI.Tests/Services/SingleFlightMemoTests.cs

@@ -199,4 +199,47 @@ public class SingleFlightMemoTests
         released.SetResult(99);
         Assert.Equal(99, await patient);
     }
+
+    /// <summary>Verifies that <c>Invalidate</c> makes a still-fresh value stale, so the next call queries again.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task Invalidate_DiscardsAFreshValue()
+    {
+        var invocations = 0;
+        var memo = new SingleFlightMemo<int>(TimeSpan.FromHours(1), () => T0);
+
+        var first = await memo.GetAsync(() => Task.FromResult(++invocations));
+        memo.Invalidate();
+        var second = await memo.GetAsync(() => Task.FromResult(++invocations));
+
+        Assert.Equal(1, first);
+        Assert.Equal(2, second);
+        Assert.Equal(2, memo.FlightCount);
+    }
+
+    /// <summary>
+    /// Verifies that a flight already running when <c>Invalidate</c> is called still answers its
+    /// callers but is not memoized: it may have read the state the invalidation says changed.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task Invalidate_DuringAFlight_ResultIsServedButNotMemoized()
+    {
+        var released = new TaskCompletionSource<int>(TaskCreationOptions.RunContinuationsAsynchronously);
+        var invocations = 0;
+        var memo = new SingleFlightMemo<int>(TimeSpan.FromHours(1), () => T0);
+
+        var inFlight = memo.GetAsync(() =>
+        {
+            invocations++;
+            return released.Task;
+        });
+        memo.Invalidate();
+        released.SetResult(7);
+
+        Assert.Equal(7, await inFlight);
+        var next = await memo.GetAsync(() => Task.FromResult(++invocations));
+        Assert.Equal(2, next);
+        Assert.Equal(2, memo.FlightCount);
+    }
 }