diff --git a/Partner-Core/src/main/java/work/slhaf/partner/module/memory/updater/MemoryUpdater.java b/Partner-Core/src/main/java/work/slhaf/partner/module/memory/updater/MemoryUpdater.java
index e397d8bc..d8b2e4ed 100644
--- a/Partner-Core/src/main/java/work/slhaf/partner/module/memory/updater/MemoryUpdater.java
+++ b/Partner-Core/src/main/java/work/slhaf/partner/module/memory/updater/MemoryUpdater.java
@@ -111,14 +111,21 @@ public class MemoryUpdater extends AbstractAgentModule.Running<PartnerRunningFlo
             return;
         }
         try {
-            List<Message> chatSnapshot = cognitionCapability.snapshotChatMessages();
-            if (chatSnapshot.size() <= 1) {
+            List<Message> fullChatSnapshot = cognitionCapability.snapshotChatMessages();
+            if (fullChatSnapshot.size() <= 1) {
+                return;
+            }
+            List<Message> chatIncrement = resolveChatIncrement(fullChatSnapshot);
+            if (chatIncrement.isEmpty()) {
+                if (refreshMemoryId) {
+                    memoryCapability.refreshMemorySession();
+                }
                 return;
             }
 
-            RollingRecord record = updateMemory(chatSnapshot);
+            RollingRecord record = updateMemory(chatIncrement);
             if (record != null) {
-                dialogRollingService.rollMessages(chatSnapshot, chatSnapshot.size(), CONTEXT_RETAIN_DIVISOR, record.unitId, record.sliceId, record.summary);
+                dialogRollingService.rollMessages(chatIncrement, fullChatSnapshot.size(), CONTEXT_RETAIN_DIVISOR, record.unitId, record.sliceId, record.summary);
             }
 
             if (refreshMemoryId) {
@@ -131,6 +138,27 @@ public class MemoryUpdater extends AbstractAgentModule.Running<PartnerRunningFlo
         }
     }
 
+    private List<Message> resolveChatIncrement(List<Message> fullChatSnapshot) {
+        String memoryId = memoryCapability.getMemorySessionId();
+        if (memoryId == null || memoryId.isBlank()) {
+            return fullChatSnapshot;
+        }
+        MemoryUnit existingUnit = memoryCapability.getMemoryUnit(memoryId);
+        if (existingUnit == null || existingUnit.getConversationMessages() == null || existingUnit.getConversationMessages().isEmpty()) {
+            return fullChatSnapshot;
+        }
+        List<Message> existingMessages = existingUnit.getConversationMessages();
+        int maxOverlap = Math.min(existingMessages.size(), fullChatSnapshot.size());
+        for (int overlap = maxOverlap; overlap > 0; overlap--) {
+            List<Message> existingSuffix = existingMessages.subList(existingMessages.size() - overlap, existingMessages.size());
+            List<Message> snapshotPrefix = fullChatSnapshot.subList(0, overlap);
+            if (existingSuffix.equals(snapshotPrefix)) {
+                return fullChatSnapshot.subList(overlap, fullChatSnapshot.size());
+            }
+        }
+        return fullChatSnapshot;
+    }
+
     private RollingRecord updateMemory(List<Message> chatSnapshot) {
         log.debug("[MemoryUpdater] 记忆更新流程开始...");
         if (chatSnapshot.isEmpty()) {
diff --git a/Partner-Core/src/test/java/work/slhaf/partner/module/memory/updater/MemoryUpdaterTest.java b/Partner-Core/src/test/java/work/slhaf/partner/module/memory/updater/MemoryUpdaterTest.java
index 694eb859..42e6b6d9 100644
--- a/Partner-Core/src/test/java/work/slhaf/partner/module/memory/updater/MemoryUpdaterTest.java
+++ b/Partner-Core/src/test/java/work/slhaf/partner/module/memory/updater/MemoryUpdaterTest.java
@@ -24,6 +24,14 @@ class MemoryUpdaterTest {
         return (MemoryUnit) method.invoke(updater, chatMessages, summarizeResult);
     }
 
+    @SuppressWarnings("unchecked")
+    private static List<Message> invokeResolveChatIncrement(MemoryUpdater updater,
+                                                            List<Message> chatMessages) throws Exception {
+        Method method = MemoryUpdater.class.getDeclaredMethod("resolveChatIncrement", List.class);
+        method.setAccessible(true);
+        return (List<Message>) method.invoke(updater, chatMessages);
+    }
+
     private static void setField(Object target, String fieldName, Object value) throws Exception {
         Field field = target.getClass().getDeclaredField(fieldName);
         field.setAccessible(true);
@@ -107,6 +115,61 @@ class MemoryUpdaterTest {
         assertEquals("fresh-summary", created.getSlices().getFirst().getSummary());
     }
 
+    @Test
+    void shouldTrimPersistedOverlapFromCurrentSnapshot() throws Exception {
+        StubMemoryCapability memoryCapability = new StubMemoryCapability("session-3");
+        MemoryUpdater updater = new MemoryUpdater();
+        setField(updater, "memoryCapability", memoryCapability);
+
+        MemoryUnit existingUnit = new MemoryUnit();
+        existingUnit.setId("session-3");
+        existingUnit.setConversationMessages(new ArrayList<>(List.of(
+                message(Message.Character.USER, "m1"),
+                message(Message.Character.ASSISTANT, "m2"),
+                message(Message.Character.USER, "m3"),
+                message(Message.Character.ASSISTANT, "m4")
+        )));
+        memoryCapability.saveMemoryUnit(existingUnit);
+
+        List<Message> increment = invokeResolveChatIncrement(
+                updater,
+                List.of(
+                        message(Message.Character.USER, "m3"),
+                        message(Message.Character.ASSISTANT, "m4"),
+                        message(Message.Character.USER, "m5"),
+                        message(Message.Character.ASSISTANT, "m6")
+                )
+        );
+
+        assertEquals(List.of("m5", "m6"), increment.stream().map(Message::getContent).toList());
+    }
+
+    @Test
+    void shouldReturnEmptyIncrementWhenSnapshotIsFullyPersisted() throws Exception {
+        StubMemoryCapability memoryCapability = new StubMemoryCapability("session-4");
+        MemoryUpdater updater = new MemoryUpdater();
+        setField(updater, "memoryCapability", memoryCapability);
+
+        MemoryUnit existingUnit = new MemoryUnit();
+        existingUnit.setId("session-4");
+        existingUnit.setConversationMessages(new ArrayList<>(List.of(
+                message(Message.Character.USER, "m1"),
+                message(Message.Character.ASSISTANT, "m2"),
+                message(Message.Character.USER, "m3")
+        )));
+        memoryCapability.saveMemoryUnit(existingUnit);
+
+        List<Message> increment = invokeResolveChatIncrement(
+                updater,
+                List.of(
+                        message(Message.Character.ASSISTANT, "m2"),
+                        message(Message.Character.USER, "m3")
+                )
+        );
+
+        assertEquals(List.of(), increment);
+    }
+
     private static final class StubMemoryCapability implements MemoryCapability {
         private final String sessionId;
         private final Map<String, MemoryUnit> units = new HashMap<>();