diff --git a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/AutoContextMemory.java b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/AutoContextMemory.java
index cb3442f97c..b4ffe32b3e 100644
--- a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/AutoContextMemory.java
+++ b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/AutoContextMemory.java
@@ -1997,6 +1997,7 @@ public List<Msg> getOriginalMemoryMsgs() {
      *   <li>Tool-related messages ({@link MsgRole#TOOL})</li>
      *   <li>System messages ({@link MsgRole#SYSTEM})</li>
      *   <li>Intermediate ASSISTANT messages that contain tool calls (not final responses)</li>
+     *   <li>Synthetic ASSISTANT messages generated by compression/offload flows</li>
      *   <li>Any other message types</li>
      * </ul>
      *
diff --git a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/MsgUtils.java b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/MsgUtils.java
index 7b21c655f2..df92b37bdb 100644
--- a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/MsgUtils.java
+++ b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/main/java/io/agentscope/core/memory/autocontext/MsgUtils.java
@@ -301,7 +301,8 @@ public static boolean isToolResultMessage(Msg msg) {
      *
      * <p>A compressed message is one that has been processed by AutoContextMemory compression
      * strategies. Compressed messages contain metadata with the {@code _compress_meta} key,
-     * which indicates that the message content has been compressed, summarized, or offloaded.
+     * which is the canonical marker for synthetic assistant summaries, offloaded payloads, and
+     * other replacement messages created by compression.
      *
      * <p>Compressed messages may have:
      * <ul>
@@ -333,30 +334,23 @@ public static boolean isCompressedMessage(Msg msg) {
     /**
      * Check if an ASSISTANT message is a final response to the user (not a tool call).
      *
-     * <p>A final assistant response should not contain ToolUseBlock, as those are intermediate
-     * tool invocation messages, not the final response returned to the user.
+     * <p>A final assistant response should not contain ToolUseBlock or ToolResultBlock, and it
+     * must not be a synthetic assistant message produced by compression. Synthetic assistant
+     * messages always carry {@code _compress_meta} metadata.
      *
      * @param msg the message to check
-     * @return true if the message is an ASSISTANT role message that does not contain tool calls
+     * @return true if the message is an ASSISTANT role message that is not synthetic and does not
+     *         contain tool calls
      */
     public static boolean isFinalAssistantResponse(Msg msg) {
         if (msg == null || msg.getRole() != MsgRole.ASSISTANT) {
             return false;
         }
 
-        // Skip compressed current round messages - they are compression results, not real assistant
-        // responses
-        Map<String, Object> metadata = msg.getMetadata();
-        if (metadata != null) {
-            Object compressMeta = metadata.get("_compress_meta");
-            // compressMeta may be null if the key doesn't exist, but instanceof handles null safely
-            if (compressMeta != null && compressMeta instanceof Map) {
-                @SuppressWarnings("unchecked")
-                Map<String, Object> compressMetaMap = (Map<String, Object>) compressMeta;
-                if (Boolean.TRUE.equals(compressMetaMap.get("compressed_current_round"))) {
-                    return false;
-                }
-            }
+        // Synthetic assistant messages are created by compression/offload flows and must not be
+        // treated as user-visible final replies.
+        if (isCompressedMessage(msg)) {
+            return false;
         }
 
         // A final response should not contain ToolUseBlock (tool calls)
diff --git a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/AutoContextMemoryTest.java b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/AutoContextMemoryTest.java
index e6fe2c9a9b..b64f91629c 100644
--- a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/AutoContextMemoryTest.java
+++ b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/AutoContextMemoryTest.java
@@ -100,6 +100,21 @@ void testAddMessage() {
         assertEquals("Hello", originalMessages.get(0).getTextContent());
     }
 
+    @Test
+    @DisplayName("Should exclude synthetic assistant messages from interaction messages")
+    void testGetInteractionMsgsSkipsSyntheticAssistant() {
+        memory.addMessage(createTextMessage("User message 1", MsgRole.USER));
+        memory.addMessage(createCompressedAssistantMessage("Compressed summary"));
+        memory.addMessage(createTextMessage("User message 2", MsgRole.USER));
+
+        List<Msg> interactionMsgs = memory.getInteractionMsgs();
+        assertEquals(2, interactionMsgs.size());
+        assertEquals(MsgRole.USER, interactionMsgs.get(0).getRole());
+        assertEquals("User message 1", interactionMsgs.get(0).getTextContent());
+        assertEquals(MsgRole.USER, interactionMsgs.get(1).getRole());
+        assertEquals("User message 2", interactionMsgs.get(1).getTextContent());
+    }
+
     @Test
     @DisplayName("Should return messages when below threshold")
     void testGetMessagesBelowThreshold() {
@@ -1085,6 +1100,20 @@ private Msg createToolResultMessage(String toolName, String callId, String resul
                 .build();
     }
 
+    private Msg createCompressedAssistantMessage(String text) {
+        Map<String, Object> metadata = new HashMap<>();
+        Map<String, Object> compressMeta = new HashMap<>();
+        compressMeta.put("offloaduuid", "uuid-1");
+        metadata.put("_compress_meta", compressMeta);
+
+        return Msg.builder()
+                .role(MsgRole.ASSISTANT)
+                .name("assistant")
+                .content(TextBlock.builder().text(text).build())
+                .metadata(metadata)
+                .build();
+    }
+
     /**
      * Simple Model implementation for testing.
      */
diff --git a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/MsgUtilsTest.java b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/MsgUtilsTest.java
index 6825331555..f85abf5ea4 100644
--- a/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/MsgUtilsTest.java
+++ b/agentscope-extensions/agentscope-extensions-autocontext-memory/src/test/java/io/agentscope/core/memory/autocontext/MsgUtilsTest.java
@@ -451,6 +451,20 @@ private Msg createToolResultMessage(String toolName, String callId, String resul
                 .build();
     }
 
+    private Msg createCompressedAssistantMessage(String text) {
+        Map<String, Object> metadata = new HashMap<>();
+        Map<String, Object> compressMeta = new HashMap<>();
+        compressMeta.put("offloaduuid", "uuid-1");
+        metadata.put("_compress_meta", compressMeta);
+
+        return Msg.builder()
+                .role(MsgRole.ASSISTANT)
+                .name("assistant")
+                .content(List.of(TextBlock.builder().text(text).build()))
+                .metadata(metadata)
+                .build();
+    }
+
     // ============================================================================
     // Tests for isToolMessage, isToolUseMessage, isToolResultMessage
     // ============================================================================
@@ -601,6 +615,15 @@ void testIsFinalAssistantResponseWithCompressedMessage() {
         assertFalse(MsgUtils.isFinalAssistantResponse(compressedMsg));
     }
 
+    @Test
+    @DisplayName("Should return false for synthetic compressed assistant message")
+    void testIsFinalAssistantResponseWithSyntheticCompressedAssistant() {
+        Msg compressedMsg = createCompressedAssistantMessage("Compressed summary");
+
+        assertTrue(MsgUtils.isCompressedMessage(compressedMsg));
+        assertFalse(MsgUtils.isFinalAssistantResponse(compressedMsg));
+    }
+
     @Test
     @DisplayName("Should return true for assistant message with null metadata")
     void testIsFinalAssistantResponseWithNullMetadata() {