diff --git a/mempalace/mcp_server.py b/mempalace/mcp_server.py
index b447249..bda4c1a 100644
--- a/mempalace/mcp_server.py
+++ b/mempalace/mcp_server.py
@@ -292,10 +292,10 @@ def tool_add_drawer(
             "matches": dup["matches"],
         }
 
-    drawer_id = f"drawer_{wing}_{room}_{hashlib.md5((content[:100] + datetime.now().isoformat()).encode()).hexdigest()[:16]}"
+    drawer_id = f"drawer_{wing}_{room}_{hashlib.md5(content.encode()).hexdigest()[:16]}"
 
     try:
-        col.add(
+        col.upsert(
             ids=[drawer_id],
             documents=[content],
             metadatas=[
diff --git a/mempalace/miner.py b/mempalace/miner.py
index 7b4e949..a53cf76 100644
--- a/mempalace/miner.py
+++ b/mempalace/miner.py
@@ -417,7 +417,7 @@ def add_drawer(
     """Add one drawer to the palace."""
     drawer_id = f"drawer_{wing}_{room}_{hashlib.md5((source_file + str(chunk_index)).encode(), usedforsecurity=False).hexdigest()[:16]}"
     try:
-        collection.add(
+        collection.upsert(
             documents=[content],
             ids=[drawer_id],
             metadatas=[
@@ -432,9 +432,7 @@ def add_drawer(
             ],
         )
         return True
-    except Exception as e:
-        if "already exists" in str(e).lower() or "duplicate" in str(e).lower():
-            return False
+    except Exception:
         raise
 
 
diff --git a/tests/test_knowledge_graph.py b/tests/test_knowledge_graph.py
index d7d9838..535eace 100644
--- a/tests/test_knowledge_graph.py
+++ b/tests/test_knowledge_graph.py
@@ -6,6 +6,7 @@ timeline, stats, and edge cases (duplicate triples, ID collisions).
 """
 
 
+
 class TestEntityOperations:
     def test_add_entity(self, kg):
         eid = kg.add_entity("Alice", entity_type="person")
@@ -124,7 +125,6 @@ class TestWALMode:
         conn.close()
         assert mode == "wal"
 
-
 class TestStats:
     def test_stats_empty(self, kg):
         stats = kg.stats()