diff --git a/core/src/main/java/com/sap/ai/sdk/core/AiCoreDeployment.java b/core/src/main/java/com/sap/ai/sdk/core/AiCoreDeployment.java
index b0620591..465b58d5 100644
--- a/core/src/main/java/com/sap/ai/sdk/core/AiCoreDeployment.java
+++ b/core/src/main/java/com/sap/ai/sdk/core/AiCoreDeployment.java
@@ -1,103 +1,44 @@
 package com.sap.ai.sdk.core;
 
-import com.sap.cloud.sdk.cloudplatform.connectivity.DefaultHttpDestination;
 import com.sap.cloud.sdk.cloudplatform.connectivity.Destination;
-import com.sap.cloud.sdk.cloudplatform.connectivity.DestinationProperty;
+import com.sap.cloud.sdk.cloudplatform.connectivity.exception.DestinationAccessException;
+import com.sap.cloud.sdk.cloudplatform.connectivity.exception.DestinationNotFoundException;
 import com.sap.cloud.sdk.services.openapi.apiclient.ApiClient;
-import java.util.function.Function;
+import java.util.function.Supplier;
 import javax.annotation.Nonnull;
 import lombok.AccessLevel;
-import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
 /** Connectivity convenience methods for AI Core with deployment. */
-@RequiredArgsConstructor(access = AccessLevel.PROTECTED)
+@RequiredArgsConstructor(access = AccessLevel.PACKAGE)
 public class AiCoreDeployment implements AiCoreDestination {
+  private final AiCoreService aiCoreService;
 
-  private static final String AI_RESOURCE_GROUP = "URL.headers.AI-Resource-Group";
-
-  // the delegating AI Core Service instance
-  @Nonnull private final AiCoreService service;
-
-  // the deployment id handler to be used, based on instance
-  @Nonnull private final Function<AiCoreDeployment, String> deploymentId;
-
-  // the resource group, "default" if null
-  @Getter(AccessLevel.PROTECTED)
-  @Nonnull
-  private final String resourceGroup;
+  @Nonnull private final Supplier<String> deploymentId;
 
   /**
-   * Default constructor with "default" resource group.
+   * Set the resource group.
    *
-   * @param service The AI Core service.
-   * @param deploymentId The deployment id handler.
+   * @param resourceGroup The resource group, default value "default".
+   * @return A new instance of the AI Core service.
    */
-  public AiCoreDeployment(
-      @Nonnull final AiCoreService service,
-      @Nonnull final Function<AiCoreDeployment, String> deploymentId) {
-    this(service, deploymentId, "default");
+  @Nonnull
+  public AiCoreDeployment withResourceGroup(@Nonnull final String resourceGroup) {
+    aiCoreService.resourceGroup = resourceGroup;
+    return this;
   }
 
   @Nonnull
   @Override
-  public Destination destination() {
-    final var dest = service.baseDestinationHandler.apply(service);
-    final var builder = service.builderHandler.apply(service, dest);
-    destinationSetUrl(builder, dest);
-    destinationSetHeaders(builder);
-    return builder.build();
+  public Destination destination() throws DestinationAccessException, DestinationNotFoundException {
+    aiCoreService.deploymentId = deploymentId.get();
+    return aiCoreService.destination();
   }
 
   @Nonnull
   @Override
   public ApiClient client() {
-    final var destination = destination();
-    return service.clientHandler.apply(service, destination);
-  }
-
-  /**
-   * Update and set the URL for the destination.
-   *
-   * @param builder The destination builder.
-   * @param dest The original destination reference.
-   */
-  protected void destinationSetUrl(
-      @Nonnull final DefaultHttpDestination.Builder builder, @Nonnull final Destination dest) {
-    String uri = dest.get(DestinationProperty.URI).get();
-    if (!uri.endsWith("/")) {
-      uri = uri + "/";
-    }
-    builder.uri(uri + "v2/inference/deployments/%s/".formatted(getDeploymentId()));
-  }
-
-  /**
-   * Update and set the default request headers for the destination.
-   *
-   * @param builder The destination builder.
-   */
-  protected void destinationSetHeaders(@Nonnull final DefaultHttpDestination.Builder builder) {
-    builder.property(AI_RESOURCE_GROUP, getResourceGroup());
-  }
-
-  /**
-   * Set the resource group.
-   *
-   * @param resourceGroup The resource group.
-   * @return A new instance of the AI Core service.
-   */
-  @Nonnull
-  public AiCoreDeployment withResourceGroup(@Nonnull final String resourceGroup) {
-    return new AiCoreDeployment(service, deploymentId, resourceGroup);
-  }
-
-  /**
-   * Get the deployment id.
-   *
-   * @return The deployment id.
-   */
-  @Nonnull
-  protected String getDeploymentId() {
-    return deploymentId.apply(this);
+    aiCoreService.deploymentId = deploymentId.get();
+    return aiCoreService.client();
   }
 }
diff --git a/core/src/main/java/com/sap/ai/sdk/core/AiCoreService.java b/core/src/main/java/com/sap/ai/sdk/core/AiCoreService.java
index c063b3c7..1d966f1c 100644
--- a/core/src/main/java/com/sap/ai/sdk/core/AiCoreService.java
+++ b/core/src/main/java/com/sap/ai/sdk/core/AiCoreService.java
@@ -32,18 +32,24 @@
 @RequiredArgsConstructor
 public class AiCoreService implements AiCoreDestination {
 
-  final Function<AiCoreService, Destination> baseDestinationHandler;
+  Function<AiCoreService, Destination> baseDestinationHandler;
   final BiFunction<AiCoreService, Destination, ApiClient> clientHandler;
   final BiFunction<AiCoreService, Destination, DefaultHttpDestination.Builder> builderHandler;
 
   private static final DeploymentCache DEPLOYMENT_CACHE = new DeploymentCache();
 
+  private static final String AI_RESOURCE_GROUP = "URL.headers.AI-Resource-Group";
+
+  /** The resource group is defined by AiCoreDeployment.withResourceGroup(). */
+  @Nonnull String resourceGroup;
+
+  /** The deployment id is set by AiCoreDeployment.destination() or AiCoreDeployment.client(). */
+  @Nonnull String deploymentId;
+
   /** The default constructor. */
   public AiCoreService() {
-    this(
-        AiCoreService::getBaseDestination,
-        AiCoreService::getApiClient,
-        AiCoreService::getDestinationBuilder);
+    this(AiCoreService::getApiClient, AiCoreService::getDestinationBuilder, "default", "");
+    baseDestinationHandler = AiCoreService::getBaseDestination;
   }
 
   @Nonnull
@@ -57,18 +63,48 @@ public ApiClient client() {
   @Override
   public Destination destination() {
     final var dest = baseDestinationHandler.apply(this);
-    return builderHandler.apply(this, dest).build();
+    final var builder = builderHandler.apply(this, dest);
+    if (!deploymentId.isEmpty()) {
+      destinationSetUrl(builder, dest);
+      destinationSetHeaders(builder);
+    }
+    return builder.build();
+  }
+
+  /**
+   * Update and set the URL for the destination.
+   *
+   * @param builder The destination builder.
+   * @param dest The original destination reference.
+   */
+  protected void destinationSetUrl(
+      @Nonnull final DefaultHttpDestination.Builder builder, @Nonnull final Destination dest) {
+    String uri = dest.get(DestinationProperty.URI).get();
+    if (!uri.endsWith("/")) {
+      uri = uri + "/";
+    }
+    builder.uri(uri + "v2/inference/deployments/%s/".formatted(deploymentId));
+  }
+
+  /**
+   * Update and set the default request headers for the destination.
+   *
+   * @param builder The destination builder.
+   */
+  protected void destinationSetHeaders(@Nonnull final DefaultHttpDestination.Builder builder) {
+    builder.property(AI_RESOURCE_GROUP, resourceGroup);
   }
 
   /**
    * Set a specific base destination.
    *
    * @param destination The destination to be used for AI Core service calls.
-   * @return A new instance of the AI Core Service based on the provided destination.
+   * @return The AI Core Service based on the provided destination.
    */
   @Nonnull
   public AiCoreService withDestination(@Nonnull final Destination destination) {
-    return new AiCoreService((service) -> destination, clientHandler, builderHandler);
+    baseDestinationHandler = (service) -> destination;
+    return this;
   }
 
   /**
@@ -79,7 +115,7 @@ public AiCoreService withDestination(@Nonnull final Destination destination) {
    */
   @Nonnull
   public AiCoreDeployment forDeployment(@Nonnull final String deploymentId) {
-    return new AiCoreDeployment(this, obj -> deploymentId);
+    return new AiCoreDeployment(this, () -> deploymentId);
   }
 
   /**
@@ -95,9 +131,7 @@ public AiCoreDeployment forDeploymentByModel(@Nonnull final String modelName)
       throws NoSuchElementException {
     return new AiCoreDeployment(
         this,
-        obj ->
-            DEPLOYMENT_CACHE.getDeploymentIdByModel(
-                this.client(), obj.getResourceGroup(), modelName));
+        () -> DEPLOYMENT_CACHE.getDeploymentIdByModel(this.client(), resourceGroup, modelName));
   }
 
   /**
@@ -113,9 +147,7 @@ public AiCoreDeployment forDeploymentByScenario(@Nonnull final String scenarioId
       throws NoSuchElementException {
     return new AiCoreDeployment(
         this,
-        obj ->
-            DEPLOYMENT_CACHE.getDeploymentIdByScenario(
-                this.client(), obj.getResourceGroup(), scenarioId));
+        () -> DEPLOYMENT_CACHE.getDeploymentIdByScenario(client(), resourceGroup, scenarioId));
   }
 
   /**
diff --git a/core/src/test/java/com/sap/ai/sdk/core/AiCoreServiceTest.java b/core/src/test/java/com/sap/ai/sdk/core/AiCoreServiceTest.java
index 7a275818..cdfd5874 100644
--- a/core/src/test/java/com/sap/ai/sdk/core/AiCoreServiceTest.java
+++ b/core/src/test/java/com/sap/ai/sdk/core/AiCoreServiceTest.java
@@ -121,7 +121,7 @@ protected ApiClient getApiClient(@Nonnull Destination destination) {
     final var destination = customServiceForDeployment.destination().asHttp();
     assertThat(destination.getUri()).hasToString("https://ai/v2/inference/deployments/deployment/");
 
-    final var resourceGroup = customServiceForDeployment.getResourceGroup();
+    final var resourceGroup = customService.resourceGroup;
     assertThat(resourceGroup).isEqualTo("group");
   }
 }