diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/OpcUaApplicationHostDisposalTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/OpcUaApplicationHostDisposalTests.cs
new file mode 100644
index 000000000..529befa86
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/OpcUaApplicationHostDisposalTests.cs
@@ -0,0 +1,164 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Opc.Ua;
+using Opc.Ua.Server;
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;
+
+/// <summary>Verifies terminal server ownership on the SDK1 host (#807).</summary>
+public sealed class OpcUaApplicationHostDisposalTests : IDisposable
+{
+    private readonly string _pki = Path.Combine(Path.GetTempPath(), $"otopcua-disposal-{Guid.NewGuid():N}");
+    private static CancellationToken Ct => TestContext.Current.CancellationToken;
+
+    /// <summary>Normal and repeated host disposal releases the actual SDK request-queue owner once.</summary>
+    [Fact]
+    public async Task Host_terminally_disposes_its_booted_server_once()
+    {
+        var (host, server) = await BootAsync();
+        try
+        {
+            await host.DisposeAsync();
+            server.TerminalDisposals.ShouldBe(1);
+            await host.DisposeAsync();
+            server.TerminalDisposals.ShouldBe(1);
+        }
+        finally { await CleanupAsync(host, server); }
+    }
+
+    /// <summary>A throwing Stop cannot bypass the separately owned terminal Dispose.</summary>
+    [Fact]
+    public async Task Stop_failure_still_terminally_disposes_the_server()
+    {
+        var (host, server) = await BootAsync();
+        server.ThrowAfterStop = true;
+        try
+        {
+            await host.DisposeAsync();
+            server.StopCalls.ShouldBe(1);
+            server.TerminalDisposals.ShouldBe(1);
+        }
+        finally { await CleanupAsync(host, server); }
+    }
+
+    /// <summary>A server accepted before startup fails remains owned by the host.</summary>
+    [Fact]
+    public async Task Partial_startup_failure_does_not_strand_the_server()
+    {
+        var host = NewHost(OpcUaHostStart.AllocateFreePort());
+        var server = new RecordingServer { ThrowDuringStart = true };
+        try
+        {
+            var failure = await Should.ThrowAsync<Exception>(() => host.StartAsync(server, Ct));
+            failure.ToString().ShouldContain("controlled partial startup");
+            await host.DisposeAsync();
+            server.TerminalDisposals.ShouldBe(1);
+        }
+        finally { await CleanupAsync(host, server); }
+    }
+
+    /// <summary>Every concurrent caller waits for the one terminal cleanup owner.</summary>
+    [Fact]
+    public async Task Concurrent_disposers_share_completion_and_one_cleanup_owner()
+    {
+        var (host, server) = await BootAsync();
+        server.BlockStop = true;
+        var calls = new List<Task>();
+        try
+        {
+            calls.Add(host.DisposeAsync().AsTask());
+            await server.StopEntered.Task.WaitAsync(TimeSpan.FromSeconds(10), Ct);
+            for (var i = 0; i < 3; i++) calls.Add(host.DisposeAsync().AsTask());
+            calls.ShouldAllBe(task => !task.IsCompleted);
+            server.StopCalls.ShouldBe(1);
+            server.TerminalDisposals.ShouldBe(0);
+            server.ReleaseStop.TrySetResult();
+            await Task.WhenAll(calls).WaitAsync(TimeSpan.FromSeconds(20), Ct);
+            server.TerminalDisposals.ShouldBe(1);
+        }
+        finally
+        {
+            server.ReleaseStop.TrySetResult();
+            try { await Task.WhenAll(calls).WaitAsync(TimeSpan.FromSeconds(20), CancellationToken.None); }
+            finally { await CleanupAsync(host, server); }
+        }
+    }
+
+    /// <summary>Terminal disposal before startup refuses a new owner instead of silently stranding it.</summary>
+    [Fact]
+    public async Task Disposed_host_rejects_start_without_taking_server_ownership()
+    {
+        var host = NewHost(OpcUaHostStart.AllocateFreePort());
+        var server = new RecordingServer();
+        try
+        {
+            await host.DisposeAsync();
+            await Should.ThrowAsync<ObjectDisposedException>(() => host.StartAsync(server, Ct));
+            server.TerminalDisposals.ShouldBe(0, "the rejected server still belongs to its caller");
+        }
+        finally { await CleanupAsync(host, server); }
+    }
+
+    private Task<(OpcUaApplicationHost Host, RecordingServer Server)> BootAsync() =>
+        OpcUaHostStart.StartAsync(NewHost, () => new RecordingServer(), Ct);
+
+    private OpcUaApplicationHost NewHost(int port) => new(new OpcUaApplicationHostOptions
+    {
+        ApplicationName = "OtOpcUa.Disposal", ApplicationUri = "urn:OtOpcUa.Disposal",
+        PublicHostname = "localhost", OpcUaPort = port, PkiStoreRoot = _pki,
+    }, NullLogger<OpcUaApplicationHost>.Instance);
+
+    private static async Task CleanupAsync(OpcUaApplicationHost host, RecordingServer server)
+    {
+        try { await host.DisposeAsync().AsTask().WaitAsync(TimeSpan.FromSeconds(20), CancellationToken.None); }
+        finally
+        {
+            // Red tests still release their test-owned server after recording the missing host disposal.
+            if (server.TerminalDisposals == 0) server.Dispose();
+        }
+    }
+
+    private sealed class RecordingServer : StandardServer
+    {
+        private int _terminalDisposals;
+        private int _stopCalls;
+        internal int TerminalDisposals => Volatile.Read(ref _terminalDisposals);
+        internal int StopCalls => Volatile.Read(ref _stopCalls);
+        internal bool ThrowDuringStart { get; init; }
+        internal bool ThrowAfterStop { get; set; }
+        internal bool BlockStop { get; set; }
+        internal TaskCompletionSource StopEntered { get; } = new(TaskCreationOptions.RunContinuationsAsynchronously);
+        internal TaskCompletionSource ReleaseStop { get; } = new(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        protected override void OnServerStarting(ApplicationConfiguration configuration)
+        {
+            base.OnServerStarting(configuration);
+            if (ThrowDuringStart) throw new InvalidOperationException("controlled partial startup");
+        }
+
+        public override async ValueTask StopAsync(CancellationToken cancellationToken = default)
+        {
+            Interlocked.Increment(ref _stopCalls);
+            if (BlockStop)
+            {
+                StopEntered.TrySetResult();
+                await ReleaseStop.Task.WaitAsync(cancellationToken);
+            }
+            await base.StopAsync(cancellationToken);
+            if (ThrowAfterStop) throw new InvalidOperationException("controlled Stop failure");
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing) Interlocked.Increment(ref _terminalDisposals);
+            base.Dispose(disposing);
+        }
+    }
+
+    /// <summary>Removes only this test's private fixture.</summary>
+    public void Dispose()
+    {
+        if (Directory.Exists(_pki)) Directory.Delete(_pki, true);
+    }
+}