diff --git a/src/langbot/pkg/pipeline/preproc/preproc.py b/src/langbot/pkg/pipeline/preproc/preproc.py
index eacf4772..c4bcf6b3 100644
--- a/src/langbot/pkg/pipeline/preproc/preproc.py
+++ b/src/langbot/pkg/pipeline/preproc/preproc.py
@@ -176,6 +176,16 @@ class PreProcessor(stage.PipelineStage):
         query.variables['user_message_text'] = plain_text
 
         query.user_message = provider_message.Message(role='user', content=content_list)
+
+        # Extract knowledge base UUIDs into query variables so plugins can modify them
+        # during PromptPreProcessing before the runner performs retrieval.
+        kb_uuids = query.pipeline_config['ai']['local-agent'].get('knowledge-bases', [])
+        if not kb_uuids:
+            old_kb_uuid = query.pipeline_config['ai']['local-agent'].get('knowledge-base', '')
+            if old_kb_uuid and old_kb_uuid != '__none__':
+                kb_uuids = [old_kb_uuid]
+        query.variables['_knowledge_base_uuids'] = list(kb_uuids)
+
         # =========== 触发事件 PromptPreProcessing
 
         event = events.PromptPreProcessing(
diff --git a/src/langbot/pkg/plugin/handler.py b/src/langbot/pkg/plugin/handler.py
index 1d190220..6ce98800 100644
--- a/src/langbot/pkg/plugin/handler.py
+++ b/src/langbot/pkg/plugin/handler.py
@@ -675,11 +675,15 @@ class RuntimeConnectionHandler(handler.Handler):
                 )
 
             try:
+                session_name = f'{query.session.launcher_type.value}_{query.session.launcher_id}'
                 entries = await kb.retrieve(
                     query_text,
                     settings={
                         'top_k': top_k,
                         'filters': filters,
+                        'session_name': session_name,
+                        'bot_uuid': query.bot_uuid or '',
+                        'sender_id': str(query.sender_id),
                     },
                 )
                 results = [entry.model_dump(mode='json') for entry in entries]
diff --git a/src/langbot/pkg/provider/runners/localagent.py b/src/langbot/pkg/provider/runners/localagent.py
index 62a534a1..65f86678 100644
--- a/src/langbot/pkg/provider/runners/localagent.py
+++ b/src/langbot/pkg/provider/runners/localagent.py
@@ -132,14 +132,9 @@ class LocalAgentRunner(runner.RequestRunner):
         """Run request"""
         pending_tool_calls = []
 
-        # Get knowledge bases list (new field)
-        kb_uuids = query.pipeline_config['ai']['local-agent'].get('knowledge-bases', [])
-
-        # Fallback to old field for backward compatibility
-        if not kb_uuids:
-            old_kb_uuid = query.pipeline_config['ai']['local-agent'].get('knowledge-base', '')
-            if old_kb_uuid and old_kb_uuid != '__none__':
-                kb_uuids = [old_kb_uuid]
+        # Get knowledge bases list from query variables (set by PreProcessor,
+        # may have been modified by plugins during PromptPreProcessing)
+        kb_uuids = query.variables.get('_knowledge_base_uuids', [])
 
         user_message = copy.deepcopy(query.user_message)