hotfix bug in pref init (#502)

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## Checklist:

- [ ] I have performed a self-review of my own code | 我已自行检查了自己的代码
- [ ] I have commented my code in hard-to-understand areas |
我已在难以理解的地方对代码进行了注释
- [ ] I have added tests that prove my fix is effective or that my
feature works | 我已添加测试以证明我的修复有效或功能正常
- [ ] I have created related documentation issue/PR in
[MemOS-Docs](https://github.com/MemTensor/MemOS-Docs) (if applicable) |
我已在 [MemOS-Docs](https://github.com/MemTensor/MemOS-Docs) 中创建了相关的文档
issue/PR（如果适用）
- [ ] I have linked the issue to this PR (if applicable) | 我已将 issue
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的人

Author: CaralHsi

README.md

@@ -53,8 +53,8 @@ Designed for **AI companions, role-playing NPCs, and multi-agent systems**, MemO
 </div>
 
 
-Get Free API: [Try API](https://memos-dashboard.openmem.net/quickstart/?source=github) 
- 
+Get Free API: [Try API](https://memos-dashboard.openmem.net/quickstart/?source=github)
+
 
 ---
 

evaluation/.env-example

@@ -21,4 +21,3 @@ MEMU_API_KEY="mu_xxx"
 SUPERMEMORY_API_KEY="sm_xxx"
 MEMOBASE_API_KEY="xxx"
 MEMOBASE_PROJECT_URL="http://***.***.***.***:8019"
-

src/memos/api/routers/server_router.py

@@ -187,32 +187,48 @@ def init_server():
 
     # Create component instances
     graph_db = GraphStoreFactory.from_config(graph_db_config)
-    vector_db = VecDBFactory.from_config(vector_db_config)
+    vector_db = (
+        VecDBFactory.from_config(vector_db_config)
+        if os.getenv("ENABLE_PREFERENCE_MEMORY", "false").lower() == "true"
+        else None
+    )
     llm = LLMFactory.from_config(llm_config)
     embedder = EmbedderFactory.from_config(embedder_config)
     mem_reader = MemReaderFactory.from_config(mem_reader_config)
     reranker = RerankerFactory.from_config(reranker_config)
     internet_retriever = InternetRetrieverFactory.from_config(
         internet_retriever_config, embedder=embedder
     )
-    pref_extractor = ExtractorFactory.from_config(
-        config_factory=pref_extractor_config,
-        llm_provider=llm,
-        embedder=embedder,
-        vector_db=vector_db,
+    pref_extractor = (
+        ExtractorFactory.from_config(
+            config_factory=pref_extractor_config,
+            llm_provider=llm,
+            embedder=embedder,
+            vector_db=vector_db,
+        )
+        if os.getenv("ENABLE_PREFERENCE_MEMORY", "false").lower() == "true"
+        else None
     )
-    pref_adder = AdderFactory.from_config(
-        config_factory=pref_adder_config,
-        llm_provider=llm,
-        embedder=embedder,
-        vector_db=vector_db,
+    pref_adder = (
+        AdderFactory.from_config(
+            config_factory=pref_adder_config,
+            llm_provider=llm,
+            embedder=embedder,
+            vector_db=vector_db,
+        )
+        if os.getenv("ENABLE_PREFERENCE_MEMORY", "false").lower() == "true"
+        else None
     )
-    pref_retriever = RetrieverFactory.from_config(
-        config_factory=pref_retriever_config,
-        llm_provider=llm,
-        embedder=embedder,
-        reranker=reranker,
-        vector_db=vector_db,
+    pref_retriever = (
+        RetrieverFactory.from_config(
+            config_factory=pref_retriever_config,
+            llm_provider=llm,
+            embedder=embedder,
+            reranker=reranker,
+            vector_db=vector_db,
+        )
+        if os.getenv("ENABLE_PREFERENCE_MEMORY", "false").lower() == "true"
+        else None
     )
 
     # Initialize memory manager

src/memos/mem_cube/navie.py

@@ -58,14 +58,18 @@ def __init__(
         )
         self._act_mem: BaseActMemory | None = None
         self._para_mem: BaseParaMemory | None = None
-        self._pref_mem: BaseTextMemory | None = SimplePreferenceTextMemory(
-            extractor_llm=llm,
-            vector_db=vector_db,
-            embedder=embedder,
-            reranker=reranker,
-            extractor=pref_extractor,
-            adder=pref_adder,
-            retriever=pref_retriever,
+        self._pref_mem: BaseTextMemory | None = (
+            SimplePreferenceTextMemory(
+                extractor_llm=llm,
+                vector_db=vector_db,
+                embedder=embedder,
+                reranker=reranker,
+                extractor=pref_extractor,
+                adder=pref_adder,
+                retriever=pref_retriever,
+            )
+            if os.getenv("ENABLE_PREFERENCE_MEMORY", "false").lower() == "true"
+            else None
         )
 
     def load(