fix(host): resolve Host-001 — exclude leader-only active-node check from /health/ready

tests/ScadaLink.Host.Tests/HealthCheckTests.cs

@@ -110,6 +110,54 @@ public class HealthCheckTests : IDisposable
         }
     }
 
+    [Fact]
+    public async Task HealthReady_Endpoint_ExcludesActiveNodeCheck()
+    {
+        // Host-001 regression: /health/ready must reflect cluster membership + DB
+        // connectivity only (REQ-HOST-4a), NOT cluster leadership. The leader-only
+        // "active-node" check belongs solely to /health/active. If /health/ready
+        // included "active-node", a fully operational standby central node would
+        // permanently report 503, breaking load-balancer failover readiness.
+        var previousEnv = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
+        try
+        {
+            Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", "Central");
+
+            var factory = new WebApplicationFactory<Program>()
+                .WithWebHostBuilder(builder =>
+                {
+                    builder.ConfigureAppConfiguration((context, config) =>
+                    {
+                        config.AddInMemoryCollection(new Dictionary<string, string?>
+                        {
+                            ["ScadaLink:Node:NodeHostname"] = "localhost",
+                            ["ScadaLink:Node:RemotingPort"] = "0",
+                            ["ScadaLink:Cluster:SeedNodes:0"] = "akka.tcp://scadalink@localhost:2551",
+                            ["ScadaLink:Cluster:SeedNodes:1"] = "akka.tcp://scadalink@localhost:2552",
+                            ["ScadaLink:Database:SkipMigrations"] = "true",
+                        });
+                    });
+                    builder.UseSetting("ScadaLink:Node:Role", "Central");
+                    builder.UseSetting("ScadaLink:Database:SkipMigrations", "true");
+                });
+            _disposables.Add(factory);
+
+            var client = factory.CreateClient();
+            _disposables.Add(client);
+
+            var response = await client.GetAsync("/health/ready");
+            var body = await response.Content.ReadAsStringAsync();
+
+            // The readiness body lists each executed check by name in its entries map.
+            // The leader-only "active-node" check must not be among them.
+            Assert.DoesNotContain("active-node", body);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", previousEnv);
+        }
+    }
+
     [Fact]
     public async Task ActiveNodeHealthCheck_SystemNotStarted_ReturnsUnhealthy()
     {