Addressed code review comments

Author: mprokopchuk

agent/src/main/java/com/cloud/agent/AgentShell.java

@@ -22,6 +22,7 @@
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.HashMap;
@@ -159,10 +160,14 @@ public String[] getHosts() {
         // Add the last successful setup host as a fallback option at the end of the host list.
         // This host is tried only after all configured hosts have failed, providing a
         // last-resort connection option since this host previously completed setup successfully.
-        if (StringUtils.isNotBlank(lastSetupCompletedHost)
-                && StringUtils.isNotBlank(_host)
-                && !_host.contains(lastSetupCompletedHost)) {
-            host = _host + "," + lastSetupCompletedHost;
+        if (StringUtils.isNotBlank(lastSetupCompletedHost) && StringUtils.isNotBlank(_host)) {
+            final String candidate = lastSetupCompletedHost.trim();
+            // Match against the exact comma-separated entries so a substring (e.g. 10.0.0.1 in
+            // 10.0.0.10) does not wrongly suppress the fallback.
+            final boolean alreadyPresent = Arrays.stream(_host.split(","))
+                    .map(String::trim)
+                    .anyMatch(candidate::equalsIgnoreCase);
+            host = alreadyPresent ? _host : _host + "," + candidate;
         } else {
             host = _host;
         }
@@ -479,7 +484,9 @@ public Integer getSslHandshakeTimeout() {
 
     @Override
     public void setLastSetupCompletedHost(String host) {
-        setPersistentProperty(null, AgentProperties.LAST_SETUP_COMPLETED_HOST.getName(), host);
+        if (StringUtils.isNotBlank(host)) {
+            setPersistentProperty(null, AgentProperties.LAST_SETUP_COMPLETED_HOST.getName(), host);
+        }
     }
 
     /**

agent/src/main/java/com/cloud/agent/IAgentShell.java

@@ -76,7 +76,8 @@ public interface IAgentShell {
     /**
      * Sets the last host where the agent successfully completed its setup process
      * and received a Ready command. This value is persisted across agent restarts
-     * and used to prioritize reconnection attempts to previously working hosts.
+     * and used as a last-resort fallback during reconnection: it is appended after
+     * the configured hosts and tried only once all of them have failed.
      *
      * @param host the hostname or IP address where the agent setup completed successfully
      */

agent/src/test/java/com/cloud/agent/AgentShellTest.java

@@ -369,4 +369,55 @@ public void testGetSslHandshakeTimeout() {
         agentPropertiesFileHandlerMocked.when(() -> AgentPropertiesFileHandler.getPropertyValue(Mockito.eq(AgentProperties.SSL_HANDSHAKE_TIMEOUT))).thenReturn(expected);
         Assert.assertEquals(expected, agentShellSpy.getSslHandshakeTimeout());
     }
+
+    private void mockLastSetupCompletedHost(String value) {
+        PowerMockito.mockStatic(AgentPropertiesFileHandler.class);
+        PowerMockito.when(AgentPropertiesFileHandler.getPropertyValue(Mockito.eq(AgentProperties.LAST_SETUP_COMPLETED_HOST))).thenReturn(value);
+    }
+
+    @Test
+    @PrepareForTest(AgentPropertiesFileHandler.class)
+    public void getHostsTestAppendsLastSetupCompletedHostAsFallback() {
+        mockLastSetupCompletedHost("30.3.3.3");
+        agentShellSpy.setHosts("10.1.1.1,20.2.2.2");
+
+        Assert.assertArrayEquals(new String[] {"10.1.1.1", "20.2.2.2", "30.3.3.3"}, agentShellSpy.getHosts());
+    }
+
+    @Test
+    @PrepareForTest(AgentPropertiesFileHandler.class)
+    public void getHostsTestSubstringHostDoesNotSuppressFallback() {
+        // 10.0.0.1 is a substring of 10.0.0.10 but not the same host, so it must still be appended.
+        mockLastSetupCompletedHost("10.0.0.1");
+        agentShellSpy.setHosts("10.0.0.10");
+
+        Assert.assertArrayEquals(new String[] {"10.0.0.10", "10.0.0.1"}, agentShellSpy.getHosts());
+    }
+
+    @Test
+    @PrepareForTest(AgentPropertiesFileHandler.class)
+    public void getHostsTestExactMatchIsNotDuplicated() {
+        mockLastSetupCompletedHost("20.2.2.2");
+        agentShellSpy.setHosts("10.1.1.1,20.2.2.2");
+
+        Assert.assertArrayEquals(new String[] {"10.1.1.1", "20.2.2.2"}, agentShellSpy.getHosts());
+    }
+
+    @Test
+    @PrepareForTest(AgentPropertiesFileHandler.class)
+    public void getHostsTestMatchIsCaseInsensitiveAndTrimmed() {
+        mockLastSetupCompletedHost("  HOSTA.EXAMPLE.COM  ");
+        agentShellSpy.setHosts("hosta.example.com,hostb.example.com");
+
+        Assert.assertArrayEquals(new String[] {"hosta.example.com", "hostb.example.com"}, agentShellSpy.getHosts());
+    }
+
+    @Test
+    @PrepareForTest(AgentPropertiesFileHandler.class)
+    public void getHostsTestBlankLastSetupCompletedHostReturnsConfiguredHostsOnly() {
+        mockLastSetupCompletedHost("  ");
+        agentShellSpy.setHosts("10.1.1.1,20.2.2.2");
+
+        Assert.assertArrayEquals(new String[] {"10.1.1.1", "20.2.2.2"}, agentShellSpy.getHosts());
+    }
 }