fix(deployment-manager): resolve DeploymentManager-003..011 — atomic status commit, orphan-delete handling, semaphore reclamation, structured diff, options binding, lifecycle test coverage

tests/ScadaLink.DeploymentManager.Tests/OperationLockManagerTests.cs

@@ -92,4 +92,52 @@ public class OperationLockManagerTests
 
         await Task.WhenAll(tasks);
     }
+
+    // ── DeploymentManager-005: semaphore must not leak ──
+
+    [Fact]
+    public async Task AcquireAsync_ReleasedLock_RemovesSemaphoreEntry()
+    {
+        // A semaphore that is created, used, and fully released must not be
+        // retained — otherwise every distinct instance name leaks a
+        // SemaphoreSlim (a kernel handle) for the life of the process.
+        using (await _lockManager.AcquireAsync("transient-inst", TimeSpan.FromSeconds(5)))
+        {
+            Assert.Equal(1, _lockManager.TrackedLockCount);
+        }
+
+        // After release, the entry is reclaimed.
+        Assert.Equal(0, _lockManager.TrackedLockCount);
+    }
+
+    [Fact]
+    public async Task AcquireAsync_ManyDistinctInstances_DoesNotAccumulateSemaphores()
+    {
+        // Simulates the long-running central process: many instances are
+        // deployed/disabled over time. Their semaphores must be reclaimed.
+        for (var i = 0; i < 100; i++)
+        {
+            using var handle = await _lockManager.AcquireAsync($"churn-{i}", TimeSpan.FromSeconds(5));
+        }
+
+        Assert.Equal(0, _lockManager.TrackedLockCount);
+    }
+
+    [Fact]
+    public async Task AcquireAsync_ContendedLock_KeepsSemaphoreUntilLastReleaseThenReclaims()
+    {
+        // While a second caller is waiting, the semaphore must survive the
+        // first release; only when the last holder releases is it reclaimed.
+        var first = await _lockManager.AcquireAsync("contended", TimeSpan.FromSeconds(5));
+
+        var secondAcquire = _lockManager.AcquireAsync("contended", TimeSpan.FromSeconds(5));
+
+        first.Dispose(); // hands the lock to the waiter; entry must NOT be removed
+        var second = await secondAcquire;
+
+        Assert.Equal(1, _lockManager.TrackedLockCount);
+        second.Dispose();
+
+        Assert.Equal(0, _lockManager.TrackedLockCount);
+    }
 }