fix: add thread-safe write lock to ChromaDB operations

src/core/db.py

@@ -1,20 +1,28 @@
 """ChromaDB 数据库层."""
+import threading
 import chromadb
 from chromadb.api.models.Collection import Collection
 
 
 class VectorDB:
-    """向量数据库封装."""
+    """线程安全的向量数据库封装."""
 
     def __init__(self, persist_dir: str = "./data"):
         self.client = chromadb.PersistentClient(path=persist_dir)
+        self._write_lock = threading.Lock()
+
+    @property
+    def write_lock(self) -> threading.Lock:
+        """获取写锁, 供外部在 add/delete/update 操作时使用."""
+        return self._write_lock
 
     def get_or_create_collection(self, name: str) -> Collection:
         """获取或创建 collection."""
         return self.client.get_or_create_collection(name=name)
 
     def delete_collection(self, name: str) -> None:
-        """删除 collection."""
+        """删除 collection (线程安全)."""
+        with self._write_lock:
             try:
                 self.client.delete_collection(name=name)
             except ValueError:

src/core/ingest.py

@@ -206,6 +206,7 @@ class DocumentIngestor:
             for i, c in enumerate(chunks)
         ]
 
+        with self.db.write_lock:
             self.collection.add(
                 ids=ids,
                 embeddings=embeddings,
@@ -226,6 +227,7 @@ class DocumentIngestor:
     def _remove_by_source(self, file_name: str) -> None:
         """按 source_file 删除已有 chunks."""
         try:
+            with self.db.write_lock:
                 existing = self.collection.get(
                     where={"source_file": file_name}
                 )

src/core/search.py

@@ -75,8 +75,9 @@ class Searcher:
         return sorted(sources)
 
     def delete_by_source(self, file_name: str) -> bool:
-        """按文件名删除文档."""
+        """按文件名删除文档 (线程安全)."""
         try:
+            with self.db.write_lock:
                 existing = self.collection.get(
                     where={"source_file": file_name}
                 )