feat: Replace the agent DSL with a composite of instanceId and task name

experimental/fluent/func/pom.xml

@@ -39,6 +39,12 @@
             <artifactId>junit-jupiter-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${version.org.mockito}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>

experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncCallTaskBuilder.java

@@ -18,6 +18,7 @@
 import io.serverlessworkflow.api.types.func.CallJava;
 import io.serverlessworkflow.api.types.func.CallTaskJava;
 import io.serverlessworkflow.api.types.func.JavaContextFunction;
+import io.serverlessworkflow.api.types.func.JavaFilterFunction;
 import io.serverlessworkflow.fluent.func.spi.ConditionalTaskBuilder;
 import io.serverlessworkflow.fluent.func.spi.FuncTaskTransformations;
 import io.serverlessworkflow.fluent.spec.TaskBaseBuilder;
@@ -61,6 +62,16 @@ public <T, V> FuncCallTaskBuilder function(
     return this;
   }
 
+  public <T, V> FuncCallTaskBuilder function(JavaFilterFunction<T, V> function) {
+    return function(function, null);
+  }
+
+  public <T, V> FuncCallTaskBuilder function(JavaFilterFunction<T, V> function, Class<T> argClass) {
+    this.callTaskJava = new CallTaskJava(CallJava.function(function, argClass));
+    super.setTask(this.callTaskJava.getCallJava());
+    return this;
+  }
+
   /** Accept a side-effect Consumer; engine should pass input through unchanged. */
   public <T> FuncCallTaskBuilder consumer(Consumer<T> consumer) {
     this.callTaskJava = new CallTaskJava(CallJava.consumer(consumer));

experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncCallStep.java

@@ -16,6 +16,7 @@
 package io.serverlessworkflow.fluent.func.dsl;
 
 import io.serverlessworkflow.api.types.func.JavaContextFunction;
+import io.serverlessworkflow.api.types.func.JavaFilterFunction;
 import io.serverlessworkflow.fluent.func.FuncCallTaskBuilder;
 import io.serverlessworkflow.fluent.func.FuncTaskItemListBuilder;
 import java.util.function.Consumer;
@@ -26,6 +27,7 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
   private final String name;
   private final Function<T, R> fn;
   private final JavaContextFunction<T, R> ctxFn;
+  private final JavaFilterFunction<T, R> filterFn;
   private final Class<T> argClass;
 
   /** Function<T,R> variant (unnamed). */
@@ -38,6 +40,7 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
     this.name = name;
     this.fn = fn;
     this.ctxFn = null;
+    this.filterFn = null;
     this.argClass = argClass;
   }
 
@@ -51,6 +54,21 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
     this.name = name;
     this.fn = null;
     this.ctxFn = ctxFn;
+    this.filterFn = null;
+    this.argClass = argClass;
+  }
+
+  /** JavaFilterFunction<T,R> variant (unnamed). */
+  FuncCallStep(JavaFilterFunction<T, R> filterFn, Class<T> argClass) {
+    this(null, filterFn, argClass);
+  }
+
+  /** JavaFilterFunction<T,R> variant (named). */
+  FuncCallStep(String name, JavaFilterFunction<T, R> filterFn, Class<T> argClass) {
+    this.name = name;
+    this.fn = null;
+    this.ctxFn = null;
+    this.filterFn = filterFn;
     this.argClass = argClass;
   }
 
@@ -60,6 +78,8 @@ protected void configure(FuncTaskItemListBuilder list, Consumer<FuncCallTaskBuil
         cb -> {
           if (ctxFn != null) {
             cb.function(ctxFn, argClass);
+          } else if (filterFn != null) {
+            cb.function(filterFn, argClass);
           } else {
             cb.function(fn, argClass);
           }

experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java

@@ -18,6 +18,7 @@
 import io.cloudevents.CloudEventData;
 import io.serverlessworkflow.api.types.FlowDirectiveEnum;
 import io.serverlessworkflow.api.types.func.JavaContextFunction;
+import io.serverlessworkflow.api.types.func.JavaFilterFunction;
 import io.serverlessworkflow.fluent.func.FuncCallTaskBuilder;
 import io.serverlessworkflow.fluent.func.FuncEmitTaskBuilder;
 import io.serverlessworkflow.fluent.func.FuncSwitchTaskBuilder;
@@ -26,6 +27,8 @@
 import io.serverlessworkflow.fluent.func.configurers.FuncTaskConfigurer;
 import io.serverlessworkflow.fluent.func.configurers.SwitchCaseConfigurer;
 import io.serverlessworkflow.fluent.func.dsl.internal.CommonFuncOps;
+import io.serverlessworkflow.impl.TaskContextData;
+import io.serverlessworkflow.impl.WorkflowContextData;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -286,7 +289,7 @@ public static <T, R> FuncCallStep<T, R> function(Function<T, R> fn, Class<T> cla
   }
 
   /**
-   * Build a call step for functions that need {@code WorkflowContextData} as the first parameter.
+   * Build a call step for functions that need {@link WorkflowContextData} as the first parameter.
    * The DSL wraps it as a {@link JavaContextFunction} and injects the runtime context.
    *
    * <p>Signature expected: {@code (ctx, payload) -> result}
@@ -297,7 +300,7 @@ public static <T, R> FuncCallStep<T, R> function(Function<T, R> fn, Class<T> cla
    * @param <R> result type
    * @return a call step
    */
-  public static <T, R> FuncCallStep<T, R> withContext(CtxBiFunction<T, R> fn, Class<T> in) {
+  public static <T, R> FuncCallStep<T, R> withContext(JavaContextFunction<T, R> fn, Class<T> in) {
     return withContext(null, fn, in);
   }
 
@@ -319,7 +322,7 @@ public static <T, R> FuncCallStep<T, R> withInstanceId(
   }
 
   /**
-   * Named variant of {@link #withContext(CtxBiFunction, Class)}.
+   * Named variant of {@link #withContext(JavaContextFunction, Class)}.
    *
    * @param name task name
    * @param fn context-aware bi-function
@@ -329,9 +332,40 @@ public static <T, R> FuncCallStep<T, R> withInstanceId(
    * @return a named call step
    */
   public static <T, R> FuncCallStep<T, R> withContext(
-      String name, CtxBiFunction<T, R> fn, Class<T> in) {
-    JavaContextFunction<T, R> jcf = (payload, wctx) -> fn.apply(wctx, payload);
-    return new FuncCallStep<>(name, jcf, in);
+      String name, JavaContextFunction<T, R> fn, Class<T> in) {
+    return new FuncCallStep<>(name, fn, in);
+  }
+
+  /**
+   * Build a call step for functions that need {@link WorkflowContextData} and {@link
+   * io.serverlessworkflow.impl.TaskContextData} as the first and second parameter. The DSL wraps it
+   * as a {@link JavaFilterFunction} and injects the runtime context.
+   *
+   * <p>Signature expected: {@code (wctx, tctx, payload) -> result}
+   *
+   * @param fn context-aware bi-function
+   * @param in payload input class
+   * @param <T> input type
+   * @param <R> result type
+   * @return a call step
+   */
+  public static <T, R> FuncCallStep<T, R> withFilter(JavaFilterFunction<T, R> fn, Class<T> in) {
+    return withFilter(null, fn, in);
+  }
+
+  /**
+   * Named variant of {@link #withFilter(JavaFilterFunction, Class)}.
+   *
+   * @param name task name
+   * @param fn context-aware bi-function
+   * @param in payload input class
+   * @param <T> input type
+   * @param <R> result type
+   * @return a named call step
+   */
+  public static <T, R> FuncCallStep<T, R> withFilter(
+      String name, JavaFilterFunction<T, R> fn, Class<T> in) {
+    return new FuncCallStep<>(name, fn, in);
   }
 
   /**
@@ -350,6 +384,38 @@ public static <T, R> FuncCallStep<T, R> withInstanceId(
     return new FuncCallStep<>(name, jcf, in);
   }
 
+  /**
+   * Builds a composition of the current workflow instance id and the definition of the task
+   * position as a JSON pointer.
+   */
+  static String defaultUniqueId(WorkflowContextData wctx, TaskContextData tctx) {
+    return String.format("%s-%s", wctx.instanceData().id(), tctx.position().jsonPointer());
+  }
+
+  /**
+   * Build a call step for functions that expect a composition with the workflow instance id and the
+   * task position as the first parameter. The instance ID is extracted from the runtime context,
+   * the task position from the definition.
+   *
+   * <p>Signature expected: {@code (uniqueId, payload) -> result}
+   *
+   * @param fn unique-id-aware bi-function
+   * @param in payload input class
+   * @param <T> input type
+   * @param <R> result type
+   * @return a call step
+   */
+  public static <T, R> FuncCallStep<T, R> withUniqueId(
+      String name, UniqueIdBiFunction<T, R> fn, Class<T> in) {
+    JavaFilterFunction<T, R> jff =
+        (payload, wctx, tctx) -> fn.apply(defaultUniqueId(wctx, tctx), payload);
+    return new FuncCallStep<>(name, jff, in);
+  }
+
+  public static <T, R> FuncCallStep<T, R> withUniqueId(UniqueIdBiFunction<T, R> fn, Class<T> in) {
+    return withUniqueId(null, fn, in);
+  }
+
   /**
    * Create a fire-and-forget side-effect step (unnamed). The consumer receives the typed input.
    *
@@ -387,12 +453,12 @@ public static <T> ConsumeStep<T> consume(String name, Consumer<T> consumer, Clas
    * @param <R> result type
    * @return a call step
    */
-  public static <T, R> FuncCallStep<T, R> agent(InstanceIdBiFunction<T, R> fn, Class<T> in) {
-    return withInstanceId(fn, in);
+  public static <T, R> FuncCallStep<T, R> agent(UniqueIdBiFunction<T, R> fn, Class<T> in) {
+    return withUniqueId(fn, in);
   }
 
   /**
-   * Named agent-style sugar. See {@link #agent(InstanceIdBiFunction, Class)}.
+   * Named agent-style sugar. See {@link #agent(UniqueIdBiFunction, Class)}.
    *
    * @param name task name
    * @param fn (instanceId, payload) -> result
@@ -402,8 +468,8 @@ public static <T, R> FuncCallStep<T, R> agent(InstanceIdBiFunction<T, R> fn, Cla
    * @return a named call step
    */
   public static <T, R> FuncCallStep<T, R> agent(
-      String name, InstanceIdBiFunction<T, R> fn, Class<T> in) {
-    return withInstanceId(name, fn, in);
+      String name, UniqueIdBiFunction<T, R> fn, Class<T> in) {
+    return withUniqueId(name, fn, in);
   }
 
   /**
@@ -677,7 +743,7 @@ public static <T> FuncTaskConfigurer switchWhenOrElse(
    *   switchWhenOrElse(".approved == true", "sendEmail", FlowDirectiveEnum.END)
    * </pre>
    *
-   * The JQ expression is evaluated against the task input at runtime.
+   * <p>The JQ expression is evaluated against the task input at runtime.
    */
   public static FuncTaskConfigurer switchWhenOrElse(
       String jqExpression, String thenTask, FlowDirectiveEnum otherwise) {
@@ -698,7 +764,7 @@ public static FuncTaskConfigurer switchWhenOrElse(
    *   switchWhenOrElse(".score >= 80", "pass", "fail")
    * </pre>
    *
-   * The JQ expression is evaluated against the task input at runtime.
+   * <p>The JQ expression is evaluated against the task input at runtime.
    */
   public static FuncTaskConfigurer switchWhenOrElse(
       String jqExpression, String thenTask, String otherwiseTask) {

experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/UniqueIdBiFunction.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * 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
+ *
+ * http://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 io.serverlessworkflow.fluent.func.dsl;
+
+/**
+ * Functions that expect a unique ID injection in runtime, typically an idempotent generated unique
+ * id based on the workflow instance id and task name.
+ *
+ * @param <T> The task payload input
+ * @param <R> The task result output
+ */
+@FunctionalInterface
+public interface UniqueIdBiFunction<T, R> {
+  R apply(String uniqueId, T object);
+}