diff --git a/server/src/main/java/com/emotion/service/impl/ShortNovelServiceImpl.java b/server/src/main/java/com/emotion/service/impl/ShortNovelServiceImpl.java
index 8e2fad3..1840474 100644
--- a/server/src/main/java/com/emotion/service/impl/ShortNovelServiceImpl.java
+++ b/server/src/main/java/com/emotion/service/impl/ShortNovelServiceImpl.java
@@ -50,6 +50,14 @@ public class ShortNovelServiceImpl implements ShortNovelService {
     private static final java.util.concurrent.ConcurrentHashMap<String, CachedSessionMeta> SESSION_ORIGINAL_QUERY_CACHE = new java.util.concurrent.ConcurrentHashMap<>();
     private static final long SESSION_TTL_MS = 30 * 60 * 1000L;
 
+    /**
+     * sessionId -> 中间步骤累积列表（跨 SSE 流保存 clarification_question/answer/outline）
+     * 用于在 novel_done 时统一创建 message，还原完整生成流程
+     * 会话超时 30 分钟（与 SESSION_ORIGINAL_QUERY_CACHE 对齐）
+     */
+    private static final java.util.concurrent.ConcurrentHashMap<String, java.util.List<JSONObject>> SESSION_STAGES_ACCUMULATOR =
+            new java.util.concurrent.ConcurrentHashMap<>();
+
     /**
      * session 元数据（含 originalQuery 和缓存时间）
      */
@@ -99,6 +107,36 @@ public class ShortNovelServiceImpl implements ShortNovelService {
         return meta.originalQuery;
     }
 
+    /**
+     * 累积中间步骤到 session 缓存
+     * 包级可见，便于单元测试
+     *
+     * @param sessionId  会话ID
+     * @param stageEntry 步骤条目（含 kind 字段：clarification_question/clarification_answer/outline）
+     */
+    static void accumulateStage(String sessionId, JSONObject stageEntry) {
+        if (sessionId == null || sessionId.isEmpty() || stageEntry == null) {
+            return;
+        }
+        SESSION_STAGES_ACCUMULATOR.computeIfAbsent(sessionId,
+                k -> new java.util.concurrent.CopyOnWriteArrayList<>()).add(stageEntry);
+    }
+
+    /**
+     * 读取并清理 session 累积的中间步骤
+     * 包级可见，便于单元测试
+     *
+     * @param sessionId 会话ID
+     * @return 步骤列表（按累积顺序），无则返回空列表
+     */
+    static java.util.List<JSONObject> drainStages(String sessionId) {
+        if (sessionId == null || sessionId.isEmpty()) {
+            return java.util.Collections.emptyList();
+        }
+        java.util.List<JSONObject> stages = SESSION_STAGES_ACCUMULATOR.remove(sessionId);
+        return stages != null ? stages : java.util.Collections.emptyList();
+    }
+
     @Autowired
     private ShortNovelConfig config;
 
diff --git a/server/src/test/java/com/emotion/service/impl/ShortNovelServiceImplTest.java b/server/src/test/java/com/emotion/service/impl/ShortNovelServiceImplTest.java
new file mode 100644
index 0000000..e14058e
--- /dev/null
+++ b/server/src/test/java/com/emotion/service/impl/ShortNovelServiceImplTest.java
@@ -0,0 +1,75 @@
+package com.emotion.service.impl;
+
+import com.alibaba.fastjson2.JSONObject;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * ShortNovelServiceImpl 静态缓存累积器单元测试
+ *
+ * @author huazhongmin
+ * @date 2026-07-26
+ */
+public class ShortNovelServiceImplTest {
+
+    @Test
+    public void testAccumulateStage_singleEntry() {
+        String sessionId = "test-session-1";
+        JSONObject entry = new JSONObject();
+        entry.put("kind", "clarification_question");
+        entry.put("card", new JSONObject().fluentPut("question", "你的咖啡馆特色？"));
+
+        ShortNovelServiceImpl.accumulateStage(sessionId, entry);
+
+        List<JSONObject> stages = ShortNovelServiceImpl.drainStages(sessionId);
+        assertEquals(1, stages.size());
+        assertEquals("clarification_question", stages.get(0).getString("kind"));
+    }
+
+    @Test
+    public void testAccumulateStage_multipleEntries_preservesOrder() {
+        String sessionId = "test-session-2";
+        ShortNovelServiceImpl.accumulateStage(sessionId,
+                new JSONObject().fluentPut("kind", "clarification_question").fluentPut("question", "Q1"));
+        ShortNovelServiceImpl.accumulateStage(sessionId,
+                new JSONObject().fluentPut("kind", "clarification_answer").fluentPut("answer", "A1"));
+        ShortNovelServiceImpl.accumulateStage(sessionId,
+                new JSONObject().fluentPut("kind", "outline").fluentPut("outline", new JSONObject()));
+
+        List<JSONObject> stages = ShortNovelServiceImpl.drainStages(sessionId);
+        assertEquals(3, stages.size());
+        assertEquals("clarification_question", stages.get(0).getString("kind"));
+        assertEquals("clarification_answer", stages.get(1).getString("kind"));
+        assertEquals("outline", stages.get(2).getString("kind"));
+    }
+
+    @Test
+    public void testDrainStages_clearsCache() {
+        String sessionId = "test-session-3";
+        ShortNovelServiceImpl.accumulateStage(sessionId,
+                new JSONObject().fluentPut("kind", "outline"));
+
+        List<JSONObject> first = ShortNovelServiceImpl.drainStages(sessionId);
+        assertEquals(1, first.size());
+
+        // 二次读取应为空（drain 后已清理）
+        List<JSONObject> second = ShortNovelServiceImpl.drainStages(sessionId);
+        assertTrue(second.isEmpty());
+    }
+
+    @Test
+    public void testAccumulateStage_nullSessionId_ignored() {
+        ShortNovelServiceImpl.accumulateStage(null,
+                new JSONObject().fluentPut("kind", "outline"));
+        assertTrue(ShortNovelServiceImpl.drainStages(null).isEmpty());
+    }
+
+    @Test
+    public void testDrainStages_unknownSession_returnsEmpty() {
+        List<JSONObject> stages = ShortNovelServiceImpl.drainStages("nonexistent-session");
+        assertTrue(stages.isEmpty());
+    }
+}