Refa: migrate document preview/download to RESTful API (#14633)

### What problem does this PR solve?

migrate document preview/download to RESTful API

### Type of change
- [x] Refactoring

api/apps/backward_compat.py

@@ -29,6 +29,8 @@ Deprecated APIs and their replacements:
 - POST /api/v1/file/convert -> POST /api/v1/files/link-to-datasets
 - GET /api/v1/file/* -> GET /api/v1/files*
 - POST /api/v1/file/* -> POST /api/v1/files*
+- GET /api/v1/document/get/{doc_id} -> GET /api/v1/documents/{doc_id}/preview
+- GET /api/v1/document/download/{doc_id} -> GET /api/v1/documents/{doc_id}/download
 - POST /api/v1/sessions/related_questions -> POST /api/v1/chat/recommandation
 - PUT (chunk update) -> PATCH (chunk update)
 """
@@ -394,6 +396,44 @@ async def deprecated_file_upload_info():
     tenant_id = current_user.id
     return await document_api.upload_info(tenant_id=tenant_id)
 
+
+# =============================================================================
+# Document APIs
+# =============================================================================
+
+@manager.route("/document/get/<doc_id>", methods=["GET"])
+@login_required
+async def deprecated_document_get(doc_id):
+    """
+    Deprecated: Use GET /api/v1/documents/{doc_id}/preview instead.
+
+    Old path: GET /api/v1/document/get/{doc_id}
+    New path: GET /api/v1/documents/{doc_id}/preview
+    """
+    logging.warning(
+        "API endpoint /api/v1/document/get/%s is deprecated. "
+        "Please use /api/v1/documents/%s/preview instead.",
+        doc_id, doc_id,
+    )
+    return await document_api.get(doc_id)
+
+
+@manager.route("/document/download/<doc_id>", methods=["GET"])
+@login_required
+async def deprecated_document_download(doc_id):
+    """
+    Deprecated: Use GET /api/v1/documents/{doc_id}/download instead.
+
+    Old path: GET /api/v1/document/download/{doc_id}
+    New path: GET /api/v1/documents/{doc_id}/download
+    """
+    logging.warning(
+        "API endpoint /api/v1/document/download/%s is deprecated. "
+        "Please use /api/v1/documents/%s/download instead.",
+        doc_id, doc_id,
+    )
+    return await document_api.download_attachment(doc_id=doc_id)
+
 # =============================================================================
 # Agent Chat API
 # =============================================================================

api/apps/document_app.py

@@ -1,71 +0,0 @@
-#
-#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
-#
-#  Licensed under the Apache License, Version 2.0 (the "License");
-#  you may not use this file except in compliance with the License.
-#  You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-#  Unless required by applicable law or agreed to in writing, software
-#  distributed under the License is distributed on an "AS IS" BASIS,
-#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-#  See the License for the specific language governing permissions and
-#  limitations under the License
-#
-import re
-
-from quart import make_response, request
-
-from api.apps import current_user, login_required
-from api.db import FileType
-from api.db.services.document_service import DocumentService
-from api.db.services.file2document_service import File2DocumentService
-from api.utils.api_utils import (
-    get_data_error_result,
-    server_error_response,
-)
-from api.utils.web_utils import CONTENT_TYPE_MAP, apply_safe_file_response_headers
-from common import settings
-from common.misc_utils import thread_pool_exec
-
-
-@manager.route("/get/<doc_id>", methods=["GET"])  # noqa: F821
-@login_required
-async def get(doc_id):
-    try:
-        e, doc = DocumentService.get_by_id(doc_id)
-        if not e:
-            return get_data_error_result(message="Document not found!")
-
-        b, n = File2DocumentService.get_storage_address(doc_id=doc_id)
-        data = await thread_pool_exec(settings.STORAGE_IMPL.get, b, n)
-        response = await make_response(data)
-
-        ext = re.search(r"\.([^.]+)$", doc.name.lower())
-        ext = ext.group(1) if ext else None
-        content_type = None
-        if ext:
-            fallback_prefix = "image" if doc.type == FileType.VISUAL.value else "application"
-            content_type = CONTENT_TYPE_MAP.get(ext, f"{fallback_prefix}/{ext}")
-        apply_safe_file_response_headers(response, content_type, ext)
-        return response
-    except Exception as e:
-        return server_error_response(e)
-
-
-@manager.route("/download/<attachment_id>", methods=["GET"])  # noqa: F821
-@login_required
-async def download_attachment(attachment_id):
-    try:
-        ext = request.args.get("ext", "markdown")
-        data = await thread_pool_exec(settings.STORAGE_IMPL.get, current_user.id, attachment_id)
-        response = await make_response(data)
-        content_type = CONTENT_TYPE_MAP.get(ext, f"application/{ext}")
-        apply_safe_file_response_headers(response, content_type, ext)
-
-        return response
-
-    except Exception as e:
-        return server_error_response(e)
-

api/apps/restful_apis/document_api.py

@@ -33,6 +33,7 @@ from api.db.services import duplicate_name
 from api.db.services.doc_metadata_service import DocMetadataService
 from api.db.db_models import Task
 from api.db.services.document_service import DocumentService
+from api.db.services.file2document_service import File2DocumentService
 from api.db.services.file_service import FileService
 from api.db.services.knowledgebase_service import KnowledgebaseService
 from api.common.check_team_permission import check_kb_team_permission
@@ -48,7 +49,7 @@ from common.constants import ParserType, RetCode, TaskStatus, SANDBOX_ARTIFACT_B
 from common.metadata_utils import convert_conditions, meta_filter, turn2jsonschema
 from common.misc_utils import get_uuid, thread_pool_exec
 from api.utils.file_utils import filename_type, thumbnail
-from api.utils.web_utils import html2pdf, is_valid_url, apply_safe_file_response_headers
+from api.utils.web_utils import CONTENT_TYPE_MAP, html2pdf, is_valid_url, apply_safe_file_response_headers
 from common.ssrf_guard import assert_url_is_safe
 from rag.nlp import search
 
@@ -1854,3 +1855,46 @@ async def batch_update_document_status(tenant_id, dataset_id):
     if has_error:
         return get_json_result(data=result, message="Partial failure", code=RetCode.SERVER_ERROR)
     return get_json_result(data=result)
+
+@manager.route("/documents/<doc_id>/preview", methods=["GET"])  # noqa: F821
+@login_required
+async def get(doc_id):
+    try:
+        e, doc = DocumentService.get_by_id(doc_id)
+        if not e:
+            return get_data_error_result(message="Document not found!")
+
+        b, n = File2DocumentService.get_storage_address(doc_id=doc_id)
+        data = await thread_pool_exec(settings.STORAGE_IMPL.get, b, n)
+        response = await make_response(data)
+
+        ext = re.search(r"\.([^.]+)$", doc.name.lower())
+        ext = ext.group(1) if ext else None
+        content_type = None
+        if ext:
+            fallback_prefix = "image" if doc.type == FileType.VISUAL.value else "application"
+            content_type = CONTENT_TYPE_MAP.get(ext, f"{fallback_prefix}/{ext}")
+        apply_safe_file_response_headers(response, content_type, ext)
+        return response
+    except Exception as e:
+        return server_error_response(e)
+
+
+@manager.route("/documents/<doc_id>/download", methods=["GET"])  # noqa: F821
+@login_required
+@add_tenant_id_to_kwargs
+async def download_attachment(tenant_id=None, doc_id=None, attachment_id=None):
+    try:
+        # Keep backward compatibility with older callers and unit tests that still
+        # pass `attachment_id` instead of the route parameter name.
+        doc_id = doc_id or attachment_id
+        ext = request.args.get("ext", "markdown")
+        data = await thread_pool_exec(settings.STORAGE_IMPL.get, tenant_id, doc_id)
+        response = await make_response(data)
+        content_type = CONTENT_TYPE_MAP.get(ext, f"application/{ext}")
+        apply_safe_file_response_headers(response, content_type, ext)
+
+        return response
+
+    except Exception as e:
+        return server_error_response(e)