diff --git a/.env.example b/.env.example
index 22b128ce8f..313024511a 100644
--- a/.env.example
+++ b/.env.example
@@ -22,6 +22,9 @@ ENABLE_RAG_CSV_SUMMARY=false
 # Set to true to preserve backing file records, storage blobs, and per-file vectors when files are removed from knowledge bases.
 ENABLE_KNOWLEDGE_FILE_RETENTION=false
 
+# Comma-separated chunk metadata keys to expose to the model alongside retrieved content.
+RAG_SOURCE_METADATA_KEYS=''
+
 # Set to false to disable workspace Tools and Functions.
 ENABLE_PLUGINS=true
 
diff --git a/backend/open_webui/env.py b/backend/open_webui/env.py
index b17df7340a..9017cafe6c 100644
--- a/backend/open_webui/env.py
+++ b/backend/open_webui/env.py
@@ -367,6 +367,9 @@ ENABLE_QUERIES_CACHE = os.getenv('ENABLE_QUERIES_CACHE', 'False').lower() == 'tr
 ENABLE_ADMIN_CHAT_ACCESS = os.getenv('ENABLE_ADMIN_CHAT_ACCESS', 'True').lower() == 'true'
 RAG_SYSTEM_CONTEXT = os.getenv('RAG_SYSTEM_CONTEXT', 'False').lower() == 'true'
 
+# Empty by default: chunk metadata also holds internal bookkeeping (file hashes, collection names, scores).
+RAG_SOURCE_METADATA_KEYS = [key.strip() for key in os.getenv('RAG_SOURCE_METADATA_KEYS', '').split(',') if key.strip()]
+
 ####################################
 # REDIS
 ####################################
diff --git a/backend/open_webui/retrieval/utils.py b/backend/open_webui/retrieval/utils.py
index 294309984e..b1946f630d 100644
--- a/backend/open_webui/retrieval/utils.py
+++ b/backend/open_webui/retrieval/utils.py
@@ -33,6 +33,7 @@ from open_webui.env import (
     ENABLE_FORWARD_USER_INFO_HEADERS,
     ENABLE_RETRIEVAL_UNSCOPED_COLLECTIONS,
     OFFLINE_MODE,
+    RAG_SOURCE_METADATA_KEYS,
 )
 from open_webui.models.access_grants import AccessGrants
 from open_webui.models.chats import Chats
@@ -1331,6 +1332,11 @@ async def filter_accessible_collections(
     return validated
 
 
+def filter_source_metadata(metadata: dict) -> dict:
+    """Keep only the chunk metadata keys the operator allowed the model to see."""
+    return {key: metadata[key] for key in RAG_SOURCE_METADATA_KEYS if metadata.get(key) is not None}
+
+
 async def get_sources_from_items(
     request,
     items,
diff --git a/backend/open_webui/tools/builtin.py b/backend/open_webui/tools/builtin.py
index ed6ad9d4a6..c3902003c9 100644
--- a/backend/open_webui/tools/builtin.py
+++ b/backend/open_webui/tools/builtin.py
@@ -28,7 +28,7 @@ from open_webui.models.memories import Memories
 from open_webui.models.messages import Message, Messages
 from open_webui.models.notes import Notes
 from open_webui.models.users import UserModel
-from open_webui.retrieval.utils import get_content_from_url
+from open_webui.retrieval.utils import filter_source_metadata, get_content_from_url
 from open_webui.retrieval.vector.async_client import ASYNC_VECTOR_DB_CLIENT
 from open_webui.routers.images import (
     CreateImageForm,
@@ -2600,6 +2600,7 @@ async def query_chat_files(
             for idx, doc in enumerate(documents):
                 metadata = metadatas[idx] if idx < len(metadatas) and isinstance(metadatas[idx], dict) else {}
                 chunk = {
+                    **filter_source_metadata(metadata),
                     'content': doc,
                     'source': metadata.get('source', metadata.get('name', source_info.get('name', 'Unknown'))),
                     'file_id': metadata.get('file_id', source_info.get('id', '')),
@@ -3312,6 +3313,7 @@ async def query_knowledge_files(
 
                 for idx, doc in enumerate(documents):
                     chunk_info = {
+                        **filter_source_metadata(metadatas[idx]),
                         'content': doc,
                         'source': metadatas[idx].get('source', metadatas[idx].get('name', 'Unknown')),
                         'file_id': metadatas[idx].get('file_id', ''),
@@ -3335,6 +3337,7 @@ async def query_knowledge_files(
             for idx, doc in enumerate(documents):
                 metadata = metadatas[idx] if idx < len(metadatas) else {}
                 chunk_info = {
+                    **filter_source_metadata(metadata),
                     'content': doc,
                     'source': metadata.get('source', metadata.get('name', knowledge.name)),
                     'file_id': metadata.get('file_id', f'external-{knowledge.id}'),
diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index c03e689ff2..b09b2a934e 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -2,6 +2,7 @@ import ast
 import asyncio
 import base64
 import copy
+import html
 import inspect
 import json
 import logging
@@ -50,7 +51,7 @@ from open_webui.models.models import Models
 from open_webui.models.notes import Notes
 from open_webui.models.oauth_sessions import OAuthSessions
 from open_webui.models.users import UserModel, Users
-from open_webui.retrieval.utils import get_sources_from_items
+from open_webui.retrieval.utils import filter_source_metadata, get_sources_from_items
 from open_webui.routers.images import (
     CreateImageForm,
     EditImageForm,
@@ -924,11 +925,17 @@ def get_source_context(sources: list, source_ids: dict = None, include_content:
             src_type = source.get('source', {}).get('type')
             src_rid = source.get('source', {}).get('id')
             body = doc if include_content else ''
+            extra_attrs = ''
+            for key, value in filter_source_metadata(meta).items():
+                if key in ('id', 'name', 'resource-type', 'resource-id'):
+                    continue
+                extra_attrs += f' {key}="{html.escape(str(value))}"'
             context_string += (
                 f'<source id="{source_ids[source_id]}"'
                 + (f' name="{src_name}"' if src_name else '')
                 + (f' resource-type="{src_type}"' if src_type else '')
                 + (f' resource-id="{src_rid}"' if src_rid else '')
+                + extra_attrs
                 + f'>{body}</source>\n'
             )
     return context_string