diff --git a/sdk-platform-java/gax-java/gax/pom.xml b/sdk-platform-java/gax-java/gax/pom.xml
index 2feb9c9aba81..4d92bdfd5255 100644
--- a/sdk-platform-java/gax-java/gax/pom.xml
+++ b/sdk-platform-java/gax-java/gax/pom.xml
@@ -115,6 +115,7 @@
                 <include>com/google/api/gax/rpc/testing/**</include>
                 <include>com/google/api/gax/rpc/mtls/**</include>
                 <include>com/google/api/gax/util/**</include>
+                <include>com/google/api/gax/logging/**</include>
                 <include>**/native-image.properties</include>
               </includes>
             </configuration>
diff --git a/sdk-platform-java/java-showcase/gapic-showcase/pom.xml b/sdk-platform-java/java-showcase/gapic-showcase/pom.xml
index bc8d2cc812b6..85f2b44a6996 100644
--- a/sdk-platform-java/java-showcase/gapic-showcase/pom.xml
+++ b/sdk-platform-java/java-showcase/gapic-showcase/pom.xml
@@ -74,6 +74,16 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-failsafe-plugin</artifactId>
+        <configuration>
+          <!-- These tests require an Env Var to be set. Use -PenvVarTest to ONLY run these tests -->
+          <excludes>
+            <exclude>**/ITActionableErrorsLogging.java</exclude>
+          </excludes>
+        </configuration>
+      </plugin>
     </plugins>
   </build>
 
@@ -274,6 +284,7 @@
                 <testExclude>**/com/google/showcase/v1beta1/it/*.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLoggingDisabled.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLogging1x.java</testExclude>
+                <testExclude>**/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java</testExclude>
               </testExcludes>
             </configuration>
           </plugin>
@@ -318,6 +329,7 @@
                 <testExclude>**/com/google/showcase/v1beta1/it/*.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLoggingDisabled.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLogging.java</testExclude>
+                <testExclude>**/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java</testExclude>
               </testExcludes>
             </configuration>
           </plugin>
@@ -363,6 +375,7 @@
                 <testExclude>**/com/google/showcase/v1beta1/it/*.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLogging1x.java</testExclude>
                 <testExclude>**/com/google/showcase/v1beta1/it/logging/ITLogging.java</testExclude>
+                <testExclude>**/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java</testExclude>
               </testExcludes>
             </configuration>
           </plugin>
@@ -388,6 +401,44 @@
         </plugins>
       </build>
     </profile>
+    <profile>
+      <id>envVarTest</id>
+      <dependencies>
+        <dependency>
+          <groupId>org.slf4j</groupId>
+          <artifactId>slf4j-api</artifactId>
+          <scope>test</scope>
+        </dependency>
+      </dependencies>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+              <testExcludes combine.self="override" />
+              <testIncludes>
+                <testInclude>**/ITActionableErrorsLogging.java</testInclude>
+              </testIncludes>
+            </configuration>
+          </plugin>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-failsafe-plugin</artifactId>
+            <configuration>
+              <!-- Clear excludes so it runs -->
+              <excludes combine.self="override" />
+              <includes>
+                <include>**/ITActionableErrorsLogging.java</include>
+              </includes>
+              <additionalClasspathElements>
+                <additionalClasspathElement>${project.basedir}/src/test/slf4j-test-provider</additionalClasspathElement>
+              </additionalClasspathElements>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
   </profiles>
 
 </project>
diff --git a/sdk-platform-java/java-showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java b/sdk-platform-java/java-showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java
new file mode 100644
index 000000000000..910ed08057e7
--- /dev/null
+++ b/sdk-platform-java/java-showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/logging/ITActionableErrorsLogging.java
@@ -0,0 +1,194 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.showcase.v1beta1.it.logging;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import com.google.api.client.http.LowLevelHttpRequest;
+import com.google.api.client.http.LowLevelHttpResponse;
+import com.google.api.client.testing.http.MockHttpTransport;
+import com.google.api.client.testing.http.MockLowLevelHttpRequest;
+import com.google.api.client.testing.http.MockLowLevelHttpResponse;
+import com.google.api.gax.core.NoCredentialsProvider;
+import com.google.api.gax.logging.TestLogger;
+import com.google.api.gax.rpc.ApiException;
+import com.google.api.gax.tracing.LoggingTracerFactory;
+import com.google.protobuf.Any;
+import com.google.rpc.ErrorInfo;
+import com.google.rpc.Status;
+import com.google.showcase.v1beta1.EchoClient;
+import com.google.showcase.v1beta1.EchoRequest;
+import com.google.showcase.v1beta1.EchoSettings;
+import com.google.showcase.v1beta1.it.util.TestClientInitializer;
+import java.io.IOException;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.LoggerFactory;
+
+public class ITActionableErrorsLogging {
+
+  private static EchoClient grpcClient;
+  private static EchoClient httpjsonClient;
+  private TestLogger testLogger;
+
+  @BeforeAll
+  static void createClients() throws Exception {
+    grpcClient =
+        TestClientInitializer.createGrpcEchoClientOpentelemetry(new LoggingTracerFactory());
+    httpjsonClient =
+        TestClientInitializer.createHttpJsonEchoClientOpentelemetry(new LoggingTracerFactory());
+  }
+
+  @AfterAll
+  static void destroyClients() throws InterruptedException {
+    grpcClient.close();
+    httpjsonClient.close();
+
+    grpcClient.awaitTermination(TestClientInitializer.AWAIT_TERMINATION_SECONDS, TimeUnit.SECONDS);
+    httpjsonClient.awaitTermination(
+        TestClientInitializer.AWAIT_TERMINATION_SECONDS, TimeUnit.SECONDS);
+  }
+
+  @BeforeEach
+  void setupTestLogger() {
+    testLogger = (TestLogger) LoggerFactory.getLogger("com.google.api.gax.tracing.LoggingTracer");
+    testLogger.getMessageList().clear();
+    testLogger.getKeyValuePairsMap().clear();
+  }
+
+  private EchoRequest buildErrorRequest() {
+    ErrorInfo errorInfo =
+        ErrorInfo.newBuilder()
+            .setReason("TEST_REASON")
+            .setDomain("test.googleapis.com")
+            .putMetadata("test_metadata", "test_value")
+            .build();
+    Status status =
+        Status.newBuilder()
+            .setCode(3) // INVALID_ARGUMENT
+            .setMessage("This is a test error")
+            .addDetails(Any.pack(errorInfo))
+            .build();
+    return EchoRequest.newBuilder().setError(status).build();
+  }
+
+  @Test
+  void testGrpc_actionableErrorLogged() {
+    EchoRequest request = buildErrorRequest();
+
+    assertThrows(ApiException.class, () -> grpcClient.echo(request));
+
+    assertThat(testLogger.getMessageList().size()).isAtLeast(1);
+    String loggedMessage = testLogger.getMessageList().get(testLogger.getMessageList().size() - 1);
+
+    assertThat(loggedMessage).contains("This is a test error");
+
+    Map<String, Object> kvps = testLogger.getKeyValuePairsMap();
+    assertThat(kvps).containsEntry("rpc.system.name", "grpc");
+    assertThat(kvps).containsEntry("rpc.method", "google.showcase.v1beta1.Echo/Echo");
+    assertThat(kvps).containsEntry("rpc.response.status_code", "INVALID_ARGUMENT");
+    assertThat(kvps).containsEntry("error.type", "TEST_REASON");
+    assertThat(kvps).containsEntry("gcp.errors.domain", "test.googleapis.com");
+    assertThat(kvps).containsEntry("gcp.errors.metadata.test_metadata", "test_value");
+  }
+
+  @Test
+  void testHttpJson_actionableErrorLogged() throws Exception {
+    // The gapic-showcase server currently returns text/plain for failEchoWithDetails instead of
+    // JSON.
+    // Additionally, sending an ErrorInfo in a request over REST fails serialization.
+    // To test HTTP JSON actionable errors logic, we use a MockHttpTransport that simulates the
+    // correct JSON format.
+    MockHttpTransport mockTransport =
+        new MockHttpTransport() {
+          @Override
+          public LowLevelHttpRequest buildRequest(String method, String url) throws IOException {
+            return new MockLowLevelHttpRequest() {
+              @Override
+              public LowLevelHttpResponse execute() throws IOException {
+                MockLowLevelHttpResponse response = new MockLowLevelHttpResponse();
+                response.setStatusCode(409); // ABORTED
+                response.setContentType("application/json");
+                String jsonError =
+                    "{\n"
+                        + "  \"error\": {\n"
+                        + "    \"code\": 409,\n"
+                        + "    \"message\": \"This is a mock JSON error generated by the server\",\n"
+                        + "    \"status\": \"ABORTED\",\n"
+                        + "    \"details\": [\n"
+                        + "      {\n"
+                        + "        \"@type\": \"type.googleapis.com/google.rpc.ErrorInfo\",\n"
+                        + "        \"reason\": \"mock_error_reason\",\n"
+                        + "        \"domain\": \"mock.googleapis.com\",\n"
+                        + "        \"metadata\": {\"mock_key\": \"mock_value\"}\n"
+                        + "      }\n"
+                        + "    ]\n"
+                        + "  }\n"
+                        + "}";
+                response.setContent(jsonError);
+                return response;
+              }
+            };
+          }
+        };
+
+    EchoSettings httpJsonEchoSettings =
+        EchoSettings.newHttpJsonBuilder()
+            .setCredentialsProvider(NoCredentialsProvider.create())
+            .setTransportChannelProvider(
+                EchoSettings.defaultHttpJsonTransportProviderBuilder()
+                    .setHttpTransport(mockTransport)
+                    .setEndpoint(TestClientInitializer.DEFAULT_HTTPJSON_ENDPOINT)
+                    .build())
+            .build();
+
+    com.google.showcase.v1beta1.stub.EchoStubSettings echoStubSettings =
+        (com.google.showcase.v1beta1.stub.EchoStubSettings)
+            httpJsonEchoSettings.getStubSettings().toBuilder()
+                .setTracerFactory(new LoggingTracerFactory())
+                .build();
+    com.google.showcase.v1beta1.stub.EchoStub stub = echoStubSettings.createStub();
+    EchoClient mockHttpJsonClient = EchoClient.create(stub);
+
+    EchoRequest request = EchoRequest.newBuilder().build();
+
+    assertThrows(ApiException.class, () -> mockHttpJsonClient.echo(request));
+
+    assertThat(testLogger.getMessageList().size()).isAtLeast(1);
+    String loggedMessage = testLogger.getMessageList().get(testLogger.getMessageList().size() - 1);
+
+    assertThat(loggedMessage).contains("This is a mock JSON error generated by the server");
+
+    Map<String, Object> kvps = testLogger.getKeyValuePairsMap();
+    assertThat(kvps).containsEntry("rpc.system.name", "http");
+    assertThat(kvps).containsEntry("http.request.method", "POST");
+    assertThat(kvps).containsEntry("url.template", "v1beta1/echo:echo");
+    assertThat(kvps).containsEntry("rpc.response.status_code", "ABORTED");
+    assertThat(kvps).containsEntry("error.type", "mock_error_reason");
+    assertThat(kvps).containsEntry("gcp.errors.domain", "mock.googleapis.com");
+    assertThat(kvps).containsEntry("gcp.errors.metadata.mock_key", "mock_value");
+
+    mockHttpJsonClient.close();
+    mockHttpJsonClient.awaitTermination(
+        TestClientInitializer.AWAIT_TERMINATION_SECONDS, TimeUnit.SECONDS);
+  }
+}
diff --git a/sdk-platform-java/java-showcase/gapic-showcase/src/test/slf4j-test-provider/META-INF/services/org.slf4j.spi.SLF4JServiceProvider b/sdk-platform-java/java-showcase/gapic-showcase/src/test/slf4j-test-provider/META-INF/services/org.slf4j.spi.SLF4JServiceProvider
new file mode 100644
index 000000000000..b97d560115b5
--- /dev/null
+++ b/sdk-platform-java/java-showcase/gapic-showcase/src/test/slf4j-test-provider/META-INF/services/org.slf4j.spi.SLF4JServiceProvider
@@ -0,0 +1 @@
+com.google.api.gax.logging.TestServiceProvider
diff --git a/sdk-platform-java/java-showcase/pom.xml b/sdk-platform-java/java-showcase/pom.xml
index a241e7677e03..41efc38e5311 100644
--- a/sdk-platform-java/java-showcase/pom.xml
+++ b/sdk-platform-java/java-showcase/pom.xml
@@ -35,6 +35,11 @@
         <type>pom</type>
         <scope>import</scope>
       </dependency>
+      <dependency>
+        <groupId>org.slf4j</groupId>
+        <artifactId>slf4j-api</artifactId>
+        <version>2.0.16</version>
+      </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-gapic-showcase-v1beta1</artifactId>