Add plugin hooks for activity, Nexus, and worker factory options

CHANGELOG.md

@@ -31,6 +31,9 @@ to docs, or any other relevant information.
   to the given name.
 - Added experimental `WorkflowUnsafe.isSubjectToReplay()`, which reports whether the calling code is re-executed on
   replay.
+- Added experimental `ActivityClientPlugin` and `NexusClientPlugin`, which plugins on the service stubs use to configure
+  `ActivityClient` and `NexusClient`. `SimplePlugin` implements both, and its builder gained
+  `addScheduleClientInterceptors`, `addActivityClientInterceptors`, and `addNexusClientInterceptors`.
 
 ### Changed
 - Release notes for all future releases are now in a single CHANGELOG.md file. `releases` directory with old release
@@ -43,6 +46,8 @@ to docs, or any other relevant information.
 - `TemporalDevServer`, `TemporalDevServerOptions`, `TestWorkflowEnvironment.startLocal`, and the `useDevServer` methods
   of `TestWorkflowRule` and `TestWorkflowExtension` are no longer marked experimental. `TemporalDevServerOptions` remain
   specific to the Temporal CLI dev server implementation and may no longer be valid if that implementation changes.
+- `SimplePlugin` now applies its data converter customizer to schedule and Nexus clients, and its context
+  propagators to schedule and activity clients. Previously `SimplePlugin.configureScheduleClient` did nothing.
 
 ### Fixed
 - Kotlin `Async` method references compiled with Kotlin 2.4 now retain their inline behavior,

temporal-sdk/src/main/java/io/temporal/client/ActivityClientImpl.java

@@ -11,6 +11,7 @@
 import io.temporal.internal.client.RootActivityClientInvoker;
 import io.temporal.internal.client.external.GenericWorkflowClientImpl;
 import io.temporal.internal.client.external.ManualActivityCompletionClientFactory;
+import io.temporal.internal.common.PluginUtils;
 import io.temporal.internal.util.MethodExtractor;
 import io.temporal.serviceclient.MetricsTag;
 import io.temporal.serviceclient.WorkflowServiceStubs;
@@ -23,20 +24,51 @@
 import java.util.Map;
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Implementation of {@link ActivityClient} that delegates calls through the activity interceptor
  * chain and ultimately to the Temporal service.
  */
 class ActivityClientImpl implements ActivityClient, ActivityClientInternal {
 
+  private static final Logger log = LoggerFactory.getLogger(ActivityClientImpl.class);
+
   private final WorkflowServiceStubs stubs;
   private final ActivityClientOptions options;
   private final ActivityClientCallsInterceptor invoker;
   private final ManualActivityCompletionClientFactory manualActivityCompletionClientFactory;
   private final Scope metricsScope;
 
   ActivityClientImpl(WorkflowServiceStubs stubs, ActivityClientOptions options) {
+    // Extract the ActivityClientPlugins propagated from the service stubs plugins.
+    ActivityClientPlugin[] propagatedPlugins =
+        PluginUtils.extractPlugins(
+            stubs.getOptions().getPlugins(),
+            ActivityClientPlugin.class,
+            ActivityClientPlugin[]::new);
+
+    // Merge propagated plugins with activity client-specified plugins.
+    ActivityClientPlugin[] mergedPlugins =
+        PluginUtils.mergePlugins(
+            propagatedPlugins,
+            options.getPlugins(),
+            ActivityClientPlugin::getName,
+            log,
+            "service stubs",
+            ActivityClientPlugin.class);
+
+    // Apply plugin configuration phase (forward order) on user-provided options,
+    // so plugins see unmodified state before defaults and plugin merging.
+    ActivityClientOptions.Builder builder = ActivityClientOptions.newBuilder(options);
+    for (ActivityClientPlugin plugin : mergedPlugins) {
+      plugin.configureActivityClient(builder);
+    }
+    // Set merged plugins after configuration, then build.
+    builder.setPlugins(mergedPlugins);
+    options = builder.build();
+
     this.stubs = stubs;
     this.options = options;
     this.metricsScope =

temporal-sdk/src/main/java/io/temporal/client/ActivityClientOptions.java

@@ -1,10 +1,12 @@
 package io.temporal.client;
 
+import io.temporal.common.Experimental;
 import io.temporal.common.context.ContextPropagator;
 import io.temporal.common.converter.DataConverter;
 import io.temporal.common.converter.GlobalDataConverter;
 import io.temporal.common.interceptors.ActivityClientInterceptor;
 import java.lang.management.ManagementFactory;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
@@ -40,12 +42,14 @@ public static final class Builder {
         Collections.emptyList();
     private static final List<ActivityClientInterceptor> EMPTY_INTERCEPTORS =
         Collections.emptyList();
+    private static final ActivityClientPlugin[] EMPTY_PLUGINS = new ActivityClientPlugin[0];
 
     private String namespace;
     private DataConverter dataConverter;
     private String identity;
     private List<ContextPropagator> contextPropagators;
     private List<ActivityClientInterceptor> interceptors;
+    private ActivityClientPlugin[] plugins;
 
     private Builder() {}
 
@@ -58,6 +62,7 @@ private Builder(ActivityClientOptions options) {
       identity = options.identity;
       contextPropagators = options.contextPropagators;
       interceptors = options.interceptors;
+      plugins = options.plugins;
     }
 
     /** Set the namespace this client will operate on. */
@@ -102,14 +107,26 @@ public Builder setInterceptors(List<ActivityClientInterceptor> interceptors) {
       return this;
     }
 
+    /**
+     * Set the plugins for this client.
+     *
+     * @param plugins specifies the plugins to use with the client.
+     */
+    @Experimental
+    public Builder setPlugins(ActivityClientPlugin... plugins) {
+      this.plugins = Objects.requireNonNull(plugins);
+      return this;
+    }
+
     public ActivityClientOptions build() {
       String name = identity == null ? ManagementFactory.getRuntimeMXBean().getName() : identity;
       return new ActivityClientOptions(
           namespace == null ? DEFAULT_NAMESPACE : namespace,
           dataConverter == null ? GlobalDataConverter.get() : dataConverter,
           name,
           contextPropagators == null ? EMPTY_CONTEXT_PROPAGATORS : contextPropagators,
-          interceptors == null ? EMPTY_INTERCEPTORS : interceptors);
+          interceptors == null ? EMPTY_INTERCEPTORS : interceptors,
+          plugins == null ? EMPTY_PLUGINS : plugins);
     }
   }
 
@@ -118,18 +135,21 @@ public ActivityClientOptions build() {
   private final String identity;
   private final List<ContextPropagator> contextPropagators;
   private final List<ActivityClientInterceptor> interceptors;
+  private final ActivityClientPlugin[] plugins;
 
   private ActivityClientOptions(
       String namespace,
       DataConverter dataConverter,
       String identity,
       List<ContextPropagator> contextPropagators,
-      List<ActivityClientInterceptor> interceptors) {
+      List<ActivityClientInterceptor> interceptors,
+      ActivityClientPlugin[] plugins) {
     this.namespace = namespace;
     this.dataConverter = dataConverter;
     this.identity = identity;
     this.contextPropagators = contextPropagators;
     this.interceptors = interceptors;
+    this.plugins = plugins;
   }
 
   /**
@@ -177,6 +197,16 @@ public List<ActivityClientInterceptor> getInterceptors() {
     return interceptors;
   }
 
+  /**
+   * Get the plugins of this client.
+   *
+   * @return The plugins to use with the client.
+   */
+  @Experimental
+  public ActivityClientPlugin[] getPlugins() {
+    return plugins;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;
@@ -186,12 +216,19 @@ public boolean equals(Object o) {
         && Objects.equals(dataConverter, that.dataConverter)
         && Objects.equals(identity, that.identity)
         && Objects.equals(contextPropagators, that.contextPropagators)
-        && Objects.equals(interceptors, that.interceptors);
+        && Objects.equals(interceptors, that.interceptors)
+        && Arrays.equals(plugins, that.plugins);
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(namespace, dataConverter, identity, contextPropagators, interceptors);
+    return Objects.hash(
+        namespace,
+        dataConverter,
+        identity,
+        contextPropagators,
+        interceptors,
+        Arrays.hashCode(plugins));
   }
 
   @Override
@@ -209,6 +246,8 @@ public String toString() {
         + contextPropagators
         + ", interceptors="
         + interceptors
+        + ", plugins="
+        + Arrays.toString(plugins)
         + '}';
   }
 }

temporal-sdk/src/main/java/io/temporal/client/ActivityClientPlugin.java

@@ -0,0 +1,34 @@
+package io.temporal.client;
+
+import io.temporal.common.Experimental;
+import javax.annotation.Nonnull;
+
+/**
+ * Plugin interface for customizing Temporal activity client configuration.
+ *
+ * <p>Plugins that implement both {@link io.temporal.serviceclient.WorkflowServiceStubsPlugin} and
+ * {@code ActivityClientPlugin} are automatically propagated from the service stubs to the activity
+ * client.
+ *
+ * @see io.temporal.serviceclient.WorkflowServiceStubsPlugin
+ */
+@Experimental
+public interface ActivityClientPlugin {
+
+  /**
+   * Returns a unique name for this plugin. Used for logging and duplicate detection. Recommended
+   * format: "organization.plugin-name" (e.g., "io.temporal.tracing")
+   *
+   * @return fully qualified plugin name
+   */
+  @Nonnull
+  String getName();
+
+  /**
+   * Allows the plugin to modify activity client options before the client is created. Called during
+   * configuration phase in forward (registration) order.
+   *
+   * @param builder the options builder to modify
+   */
+  void configureActivityClient(@Nonnull ActivityClientOptions.Builder builder);
+}

temporal-sdk/src/main/java/io/temporal/client/NexusClientImpl.java

@@ -17,6 +17,7 @@
 import io.temporal.internal.client.RootNexusClientInvoker;
 import io.temporal.internal.client.external.GenericWorkflowClient;
 import io.temporal.internal.client.external.GenericWorkflowClientImpl;
+import io.temporal.internal.common.PluginUtils;
 import io.temporal.serviceclient.MetricsTag;
 import io.temporal.serviceclient.WorkflowServiceStubs;
 import java.util.List;
@@ -39,6 +40,32 @@ public class NexusClientImpl implements NexusClient {
 
   public static NexusClient newInstance(WorkflowServiceStubs service, NexusClientOptions options) {
     enforceNonWorkflowThread();
+
+    // Extract the NexusClientPlugins propagated from the service stubs plugins.
+    NexusClientPlugin[] propagatedPlugins =
+        PluginUtils.extractPlugins(
+            service.getOptions().getPlugins(), NexusClientPlugin.class, NexusClientPlugin[]::new);
+
+    // Merge propagated plugins with Nexus client-specified plugins.
+    NexusClientPlugin[] mergedPlugins =
+        PluginUtils.mergePlugins(
+            propagatedPlugins,
+            options.getPlugins(),
+            NexusClientPlugin::getName,
+            log,
+            "service stubs",
+            NexusClientPlugin.class);
+
+    // Apply plugin configuration phase (forward order) on user-provided options,
+    // so plugins see unmodified state before defaults and plugin merging.
+    NexusClientOptions.Builder builder = NexusClientOptions.newBuilder(options);
+    for (NexusClientPlugin plugin : mergedPlugins) {
+      plugin.configureNexusClient(builder);
+    }
+    // Set merged plugins after configuration, then build.
+    builder.setPlugins(mergedPlugins);
+    options = builder.build();
+
     return WorkflowThreadMarker.protectFromWorkflowThread(
         new NexusClientImpl(service, options.toResolvedOptions()), NexusClient.class);
   }

temporal-sdk/src/main/java/io/temporal/client/NexusClientOptions.java

@@ -11,6 +11,7 @@
 import java.lang.management.ManagementFactory;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import javax.annotation.Nullable;
 
 /**
@@ -42,18 +43,21 @@ public class NexusClientOptions {
   private final DataConverter dataConverter;
   private final String identity;
   private final @Nullable ExternalStorage externalStorage;
+  private final NexusClientPlugin[] plugins;
 
   private NexusClientOptions(
       String namespace,
       List<NexusClientInterceptor> interceptors,
       DataConverter dataConverter,
       String identity,
-      @Nullable ExternalStorage externalStorage) {
+      @Nullable ExternalStorage externalStorage,
+      NexusClientPlugin[] plugins) {
     this.namespace = namespace;
     this.interceptors = interceptors;
     this.dataConverter = dataConverter;
     this.identity = identity;
     this.externalStorage = externalStorage;
+    this.plugins = plugins;
   }
 
   /** Get the namespace this client will operate on. */
@@ -88,6 +92,11 @@ public String getIdentity() {
     return identity;
   }
 
+  /** Get the plugins of this client. */
+  public NexusClientPlugin[] getPlugins() {
+    return plugins;
+  }
+
   /**
    * Converts this {@link NexusClientOptions} instance into a {@link NexusClientResolvedOptions}
    * instance, which contains the fully resolved runtime settings used by the internal Nexus client.
@@ -130,11 +139,14 @@ public static NexusClientOptions getDefaultInstance() {
 
   /** Builder for {@link NexusClientOptions}. */
   public static class Builder {
+    private static final NexusClientPlugin[] EMPTY_PLUGINS = new NexusClientPlugin[0];
+
     private String namespace;
     private List<NexusClientInterceptor> interceptors = Collections.emptyList();
     private DataConverter dataConverter = GlobalDataConverter.get();
     private String identity;
     private ExternalStorage externalStorage;
+    private NexusClientPlugin[] plugins;
 
     private Builder() {}
 
@@ -147,6 +159,7 @@ private Builder(NexusClientOptions options) {
       dataConverter = options.dataConverter;
       identity = options.identity;
       externalStorage = options.externalStorage;
+      plugins = options.plugins;
     }
 
     /** Set the namespace this client will operate on. */
@@ -195,6 +208,16 @@ public NexusClientOptions.Builder setExternalStorage(
       return this;
     }
 
+    /**
+     * Set the plugins for this client.
+     *
+     * @param plugins specifies the plugins to use with the client.
+     */
+    public NexusClientOptions.Builder setPlugins(NexusClientPlugin... plugins) {
+      this.plugins = Objects.requireNonNull(plugins);
+      return this;
+    }
+
     public NexusClientOptions build() {
       String resolvedIdentity =
           identity == null ? ManagementFactory.getRuntimeMXBean().getName() : identity;
@@ -203,7 +226,8 @@ public NexusClientOptions build() {
           interceptors,
           dataConverter,
           resolvedIdentity,
-          externalStorage);
+          externalStorage,
+          plugins == null ? EMPTY_PLUGINS : plugins);
     }
   }
 }