enh: enable selecting individual files from collection

backend/open_webui/apps/webui/models/knowledge.py

@@ -6,6 +6,10 @@ import uuid
 
 from open_webui.apps.webui.internal.db import Base, get_db
 from open_webui.env import SRC_LOG_LEVELS
+
+from open_webui.apps.webui.models.files import FileMetadataResponse
+
+
 from pydantic import BaseModel, ConfigDict
 from sqlalchemy import BigInteger, Column, String, Text, JSON
 
@@ -64,6 +68,8 @@ class KnowledgeResponse(BaseModel):
     created_at: int  # timestamp in epoch
     updated_at: int  # timestamp in epoch
 
+    files: Optional[list[FileMetadataResponse | dict]] = None
+
 
 class KnowledgeForm(BaseModel):
     name: str