diff --git a/agentscope-core/src/main/java/io/agentscope/core/model/DashScopeChatModel.java b/agentscope-core/src/main/java/io/agentscope/core/model/DashScopeChatModel.java
index 88e5be749..85828bfd1 100644
--- a/agentscope-core/src/main/java/io/agentscope/core/model/DashScopeChatModel.java
+++ b/agentscope-core/src/main/java/io/agentscope/core/model/DashScopeChatModel.java
@@ -188,8 +188,8 @@ private Flux<ChatResponse> streamWithHttpClient(
         Instant start = Instant.now();
         boolean useMultimodal = requiresMultiModalApi();
 
-        // Get effective options
-        GenerateOptions effectiveOptions = options != null ? options : defaultOptions;
+        // Merge options with defaultOptions (options takes precedence)
+        GenerateOptions effectiveOptions = GenerateOptions.mergeOptions(options, defaultOptions);
         ToolChoice toolChoice = effectiveOptions.getToolChoice();
 
         // Format messages using formatter
diff --git a/agentscope-core/src/main/java/io/agentscope/core/pipeline/FanoutPipeline.java b/agentscope-core/src/main/java/io/agentscope/core/pipeline/FanoutPipeline.java
index 37b0badf7..ef9fa151a 100644
--- a/agentscope-core/src/main/java/io/agentscope/core/pipeline/FanoutPipeline.java
+++ b/agentscope-core/src/main/java/io/agentscope/core/pipeline/FanoutPipeline.java
@@ -16,6 +16,8 @@
 package io.agentscope.core.pipeline;
 
 import io.agentscope.core.agent.AgentBase;
+import io.agentscope.core.agent.Event;
+import io.agentscope.core.agent.StreamOptions;
 import io.agentscope.core.exception.CompositeAgentException;
 import io.agentscope.core.message.Msg;
 import java.util.ArrayList;
@@ -227,6 +229,131 @@ public String getDescription() {
         return description;
     }
 
+    // ==================== Streaming API ====================
+
+    /**
+     * Stream execution events from all agents with default options.
+     *
+     * <p>Events from multiple agents are merged (concurrent mode) or concatenated
+     * (sequential mode) based on the pipeline configuration.
+     *
+     * @param input Input message to distribute to all agents
+     * @return Flux of events emitted during execution from all agents
+     */
+    public Flux<Event> stream(Msg input) {
+        return stream(input, StreamOptions.defaults());
+    }
+
+    /**
+     * Stream execution events from all agents with specified options.
+     *
+     * <p>Events from multiple agents are merged (concurrent mode) or concatenated
+     * (sequential mode) based on the pipeline configuration.
+     *
+     * @param input Input message to distribute to all agents
+     * @param options Stream configuration options
+     * @return Flux of events emitted during execution from all agents
+     */
+    public Flux<Event> stream(Msg input, StreamOptions options) {
+        return stream(input, options, null);
+    }
+
+    /**
+     * Stream execution events from all agents with structured output support.
+     *
+     * <p>Events from multiple agents are merged (concurrent mode) or concatenated
+     * (sequential mode) based on the pipeline configuration.
+     *
+     * @param input Input message to distribute to all agents
+     * @param options Stream configuration options
+     * @param structuredOutputClass The class type for structured output (optional)
+     * @return Flux of events emitted during execution from all agents
+     */
+    public Flux<Event> stream(Msg input, StreamOptions options, Class<?> structuredOutputClass) {
+        if (agents.isEmpty()) {
+            return Flux.empty();
+        }
+
+        StreamOptions effectiveOptions = options != null ? options : StreamOptions.defaults();
+
+        return enableConcurrent
+                ? streamConcurrent(input, effectiveOptions, structuredOutputClass)
+                : streamSequential(input, effectiveOptions, structuredOutputClass);
+    }
+
+    /**
+     * Stream events from all agents concurrently.
+     *
+     * <p>All agents execute in parallel and their events are merged into a single stream.
+     * Events may arrive interleaved from different agents.
+     *
+     * @param input Input message to distribute to all agents
+     * @param options Stream configuration options
+     * @param structuredOutputClass The class type for structured output (optional)
+     * @return Flux of merged events from all agents
+     */
+    private Flux<Event> streamConcurrent(
+            Msg input, StreamOptions options, Class<?> structuredOutputClass) {
+        List<CompositeAgentException.AgentExceptionInfo> errors =
+                Collections.synchronizedList(new ArrayList<>());
+
+        List<Flux<Event>> agentFluxes =
+                agents.stream()
+                        .map(
+                                agent -> {
+                                    Flux<Event> flux =
+                                            structuredOutputClass != null
+                                                    ? agent.stream(
+                                                            input, options, structuredOutputClass)
+                                                    : agent.stream(input, options);
+
+                                    return flux.subscribeOn(scheduler)
+                                            .doOnError(
+                                                    throwable ->
+                                                            errors.add(
+                                                                    new CompositeAgentException
+                                                                            .AgentExceptionInfo(
+                                                                            agent.getAgentId(),
+                                                                            agent.getName(),
+                                                                            throwable)))
+                                            .onErrorResume(e -> Flux.empty());
+                                })
+                        .toList();
+
+        return Flux.merge(agentFluxes)
+                .doOnComplete(
+                        () -> {
+                            if (!errors.isEmpty()) {
+                                throw new CompositeAgentException(
+                                        "Multiple agent streaming failures occurred", errors);
+                            }
+                        });
+    }
+
+    /**
+     * Stream events from all agents sequentially.
+     *
+     * <p>Agents execute one after another. Events from each agent are emitted
+     * in order before the next agent starts.
+     *
+     * @param input Input message to distribute to all agents
+     * @param options Stream configuration options
+     * @param structuredOutputClass The class type for structured output (optional)
+     * @return Flux of concatenated events from all agents
+     */
+    private Flux<Event> streamSequential(
+            Msg input, StreamOptions options, Class<?> structuredOutputClass) {
+        List<Flux<Event>> chain = new ArrayList<>();
+        for (AgentBase agent : agents) {
+            Flux<Event> flux =
+                    structuredOutputClass != null
+                            ? agent.stream(input, options, structuredOutputClass)
+                            : agent.stream(input, options);
+            chain.add(flux);
+        }
+        return Flux.concat(chain);
+    }
+
     @Override
     public String toString() {
         return String.format(
diff --git a/agentscope-core/src/main/java/io/agentscope/core/rag/GenericRAGHook.java b/agentscope-core/src/main/java/io/agentscope/core/rag/GenericRAGHook.java
index 3d0b65b93..ed9e46475 100644
--- a/agentscope-core/src/main/java/io/agentscope/core/rag/GenericRAGHook.java
+++ b/agentscope-core/src/main/java/io/agentscope/core/rag/GenericRAGHook.java
@@ -145,11 +145,11 @@ private Mono<PreCallEvent> handlePreCall(PreCallEvent event) {
                             if (retrievedDocs == null || retrievedDocs.isEmpty()) {
                                 return Mono.just(event);
                             }
-                            List<Msg> enhancedMessages = new ArrayList<>();
+                            List<Msg> enhancedMessages = new ArrayList<>(inputMessages.size() + 1);
                             // Build enhanced messages with knowledge context
                             Msg enhancedMessage = createEnhancedMessages(retrievedDocs);
-                            enhancedMessages.addAll(inputMessages);
                             enhancedMessages.add(enhancedMessage);
+                            enhancedMessages.addAll(inputMessages);
                             event.setInputMessages(enhancedMessages);
                             return Mono.just(event);
                         })
diff --git a/agentscope-core/src/test/java/io/agentscope/core/pipeline/FanoutPipelineTest.java b/agentscope-core/src/test/java/io/agentscope/core/pipeline/FanoutPipelineTest.java
index 58ad38a9a..32d917908 100644
--- a/agentscope-core/src/test/java/io/agentscope/core/pipeline/FanoutPipelineTest.java
+++ b/agentscope-core/src/test/java/io/agentscope/core/pipeline/FanoutPipelineTest.java
@@ -23,6 +23,9 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import io.agentscope.core.ReActAgent;
+import io.agentscope.core.agent.Event;
+import io.agentscope.core.agent.EventType;
+import io.agentscope.core.agent.StreamOptions;
 import io.agentscope.core.agent.test.MockModel;
 import io.agentscope.core.agent.test.TestUtils;
 import io.agentscope.core.exception.CompositeAgentException;
@@ -32,6 +35,7 @@
 import java.time.Duration;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
@@ -213,4 +217,152 @@ private ReActAgent createAgent(String name, MockModel model) {
                 // safety
                 .build();
     }
+
+    // ==================== Streaming Tests ====================
+
+    @Test
+    @DisplayName("Should stream events from all agents when running concurrently")
+    void shouldStreamEventsConcurrently() {
+        ReActAgent agent1 = createAgent("Agent1", model1);
+        ReActAgent agent2 = createAgent("Agent2", model2);
+
+        FanoutPipeline pipeline = new FanoutPipeline(List.of(agent1, agent2));
+
+        Msg input = TestUtils.createUserMessage("User", "stream fanout");
+        List<Event> events = pipeline.stream(input).collectList().block(TIMEOUT);
+
+        assertNotNull(events, "Streaming pipeline should produce events");
+        assertFalse(events.isEmpty(), "Events should not be empty");
+
+        // Verify we got AGENT_RESULT events from both agents
+        long agentResultCount =
+                events.stream().filter(e -> e.getType() == EventType.AGENT_RESULT).count();
+        assertEquals(2, agentResultCount, "Expected AGENT_RESULT from each agent");
+
+        // Verify models were called
+        assertEquals(1, model1.getCallCount(), "First model should be invoked once");
+        assertEquals(1, model2.getCallCount(), "Second model should be invoked once");
+    }
+
+    @Test
+    @DisplayName("Should stream events sequentially when configured")
+    void shouldStreamEventsSequentially() {
+        ReActAgent agent1 = createAgent("Agent1", model1);
+        ReActAgent agent2 = createAgent("Agent2", model2);
+
+        FanoutPipeline pipeline = new FanoutPipeline(List.of(agent1, agent2), false);
+
+        Msg input = TestUtils.createUserMessage("User", "sequential stream");
+        List<Event> events = pipeline.stream(input).collectList().block(TIMEOUT);
+
+        assertNotNull(events, "Sequential streaming should return events");
+        assertFalse(pipeline.isConcurrentEnabled(), "Pipeline should be sequential");
+
+        // Verify we got AGENT_RESULT events
+        long agentResultCount =
+                events.stream().filter(e -> e.getType() == EventType.AGENT_RESULT).count();
+        assertEquals(2, agentResultCount, "Expected AGENT_RESULT from each agent");
+
+        // Find agent result events and verify order
+        List<Event> agentResults =
+                events.stream().filter(e -> e.getType() == EventType.AGENT_RESULT).toList();
+
+        assertEquals(
+                "Agent1",
+                agentResults.get(0).getMessage().getName(),
+                "First agent response should lead");
+        assertEquals(
+                "Agent2",
+                agentResults.get(1).getMessage().getName(),
+                "Second agent response should follow");
+    }
+
+    @Test
+    @DisplayName("Should stream with custom StreamOptions")
+    void shouldStreamWithCustomOptions() {
+        ReActAgent agent1 = createAgent("Agent1", model1);
+        ReActAgent agent2 = createAgent("Agent2", model2);
+
+        FanoutPipeline pipeline = new FanoutPipeline(List.of(agent1, agent2));
+
+        // Only stream AGENT_RESULT events
+        StreamOptions options =
+                StreamOptions.builder()
+                        .eventTypes(EventType.AGENT_RESULT)
+                        .incremental(true)
+                        .build();
+
+        Msg input = TestUtils.createUserMessage("User", "options test");
+        List<Event> events = pipeline.stream(input, options).collectList().block(TIMEOUT);
+
+        assertNotNull(events, "Streaming with options should return events");
+
+        // All events should be AGENT_RESULT type
+        boolean allAgentResults =
+                events.stream().allMatch(e -> e.getType() == EventType.AGENT_RESULT);
+        assertTrue(allAgentResults, "All events should be AGENT_RESULT");
+    }
+
+    @Test
+    @DisplayName("Should return empty flux for empty pipeline")
+    void shouldReturnEmptyFluxForEmptyPipeline() {
+        FanoutPipeline pipeline = new FanoutPipeline(List.of());
+
+        Msg input = TestUtils.createUserMessage("User", "empty pipeline");
+        List<Event> events = pipeline.stream(input).collectList().block(TIMEOUT);
+
+        assertNotNull(events, "Should return empty list");
+        assertTrue(events.isEmpty(), "Empty pipeline should produce no events");
+    }
+
+    @Test
+    @DisplayName("Should stream events through builder-created pipeline")
+    void shouldStreamEventsViaBuilder() {
+        ReActAgent agent1 = createAgent("Agent1", model1);
+        ReActAgent agent2 = createAgent("Agent2", model2);
+        ReActAgent agent3 = createAgent("Agent3", model3);
+
+        FanoutPipeline pipeline =
+                FanoutPipeline.builder()
+                        .addAgent(agent1)
+                        .addAgents(List.of(agent2, agent3))
+                        .sequential()
+                        .build();
+
+        Msg input = TestUtils.createUserMessage("User", "builder stream");
+        List<Event> events = pipeline.stream(input).collectList().block(TIMEOUT);
+
+        assertNotNull(events, "Builder-produced pipeline should stream events");
+
+        // Verify agent results in order (sequential mode)
+        List<String> agentNames =
+                events.stream()
+                        .filter(e -> e.getType() == EventType.AGENT_RESULT)
+                        .map(e -> e.getMessage().getName())
+                        .toList();
+
+        assertEquals(
+                List.of("Agent1", "Agent2", "Agent3"),
+                agentNames,
+                "Sequential streaming should maintain insertion order");
+    }
+
+    @Test
+    @DisplayName("Should collect events count correctly in concurrent streaming")
+    void shouldCollectCorrectEventCountConcurrently() {
+        ReActAgent agent1 = createAgent("Agent1", model1);
+        ReActAgent agent2 = createAgent("Agent2", model2);
+        ReActAgent agent3 = createAgent("Agent3", model3);
+
+        FanoutPipeline pipeline = new FanoutPipeline(List.of(agent1, agent2, agent3));
+
+        Msg input = TestUtils.createUserMessage("User", "count test");
+
+        AtomicInteger eventCount = new AtomicInteger(0);
+        pipeline.stream(input).doOnNext(event -> eventCount.incrementAndGet()).blockLast(TIMEOUT);
+
+        assertTrue(
+                eventCount.get() >= 3,
+                "Should have at least 3 AGENT_RESULT events (one per agent)");
+    }
 }