Fix: correct regex for file-preview URL re-signing (#25620)

Fixes #25619

The regex patterns for file-preview and image-preview contained an unescaped `?`, 
which caused incorrect matches such as `file-previe` or `image-previw`. 
This led to malformed URLs being incorrectly re-signed.

Changes:
- Escape `?` in both file-preview and image-preview regex patterns.
- Ensure only valid URLs are re-signed.

Added unit tests to cover:
- Valid file-preview and image-preview URLs (correctly re-signed).
- Misspelled file/image preview URLs (no longer incorrectly matched).

Other:
- Fix a deprecated function `datetime.utcnow()`

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Asuka Minato <i@asukaminato.eu.org>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

api/models/model.py

                 sign_url = sign_tool_file(tool_file_id=tool_file_id, extension=extension)
             elif "file-preview" in url:
                 # get upload file id
-                upload_file_id_pattern = r"\/files\/([\w-]+)\/file-preview?\?timestamp="
+                upload_file_id_pattern = r"\/files\/([\w-]+)\/file-preview\?timestamp="
                 result = re.search(upload_file_id_pattern, url)
                 if not result:
                     continue
                 sign_url = file_helpers.get_signed_file_url(upload_file_id)
             elif "image-preview" in url:
                 # image-preview is deprecated, use file-preview instead
-                upload_file_id_pattern = r"\/files\/([\w-]+)\/image-preview?\?timestamp="
+                upload_file_id_pattern = r"\/files\/([\w-]+)\/image-preview\?timestamp="
                 result = re.search(upload_file_id_pattern, url)
                 if not result:
                     continue

api/tests/test_containers_integration_tests/tasks/test_batch_clean_document_task.py

 from faker import Faker
 
 from extensions.ext_database import db
+from libs.datetime_utils import naive_utc_now
 from models.account import Account, Tenant, TenantAccountJoin, TenantAccountRole
 from models.dataset import Dataset, Document, DocumentSegment
 from models.model import UploadFile
             UploadFile: Created upload file instance
         """
         fake = Faker()
-        from datetime import datetime
 
         from models.enums import CreatorUserRole
 
             mime_type="text/plain",
             created_by_role=CreatorUserRole.ACCOUNT,
             created_by=account.id,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
             used=False,
         )
 

api/tests/unit_tests/core/repositories/test_workflow_node_execution_conflict_handling.py

 """Unit tests for workflow node execution conflict handling."""
 
-from datetime import datetime
 from unittest.mock import MagicMock, Mock
 
 import psycopg2.errors
     WorkflowNodeExecutionStatus,
 )
 from core.workflow.enums import NodeType
+from libs.datetime_utils import naive_utc_now
 from models import Account, WorkflowNodeExecutionTriggeredFrom
 
 
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         original_id = execution.id
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.SUCCEEDED,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should update existing record
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should raise IntegrityError after max retries
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should raise error immediately

api/tests/unit_tests/models/test_model.py

+import importlib
+import types
+
+import pytest
+
+from models.model import Message
+
+
+@pytest.fixture(autouse=True)
+def patch_file_helpers(monkeypatch: pytest.MonkeyPatch):
+    """
+    Patch file_helpers.get_signed_file_url to a deterministic stub.
+    """
+    model_module = importlib.import_module("models.model")
+    dummy = types.SimpleNamespace(get_signed_file_url=lambda fid: f"https://signed.example/{fid}")
+    # Inject/override file_helpers on models.model
+    monkeypatch.setattr(model_module, "file_helpers", dummy, raising=False)
+
+
+def _wrap_md(url: str) -> str:
+    """
+    Wrap a raw URL into the markdown that re_sign_file_url_answer expects:
+    [link](<url>)
+    """
+    return f"please click [file]({url}) to download."
+
+
+def test_file_preview_valid_replaced():
+    """
+    Valid file-preview URL must be re-signed:
+    - Extract upload_file_id correctly
+    - Replace the original URL with the signed URL
+    """
+    upload_id = "abc-123"
+    url = f"/files/{upload_id}/file-preview?timestamp=111&nonce=222&sign=333"
+    msg = Message(answer=_wrap_md(url))
+
+    out = msg.re_sign_file_url_answer
+    assert f"https://signed.example/{upload_id}" in out
+    assert url not in out
+
+
+def test_file_preview_misspelled_not_replaced():
+    """
+    Misspelled endpoint 'file-previe?timestamp=' should NOT be rewritten.
+    """
+    upload_id = "zzz-001"
+    # path deliberately misspelled: file-previe? (missing 'w')
+    # and we append &note=file-preview to trick the old `"file-preview" in url` check.
+    url = f"/files/{upload_id}/file-previe?timestamp=111&nonce=222&sign=333&note=file-preview"
+    original = _wrap_md(url)
+    msg = Message(answer=original)
+
+    out = msg.re_sign_file_url_answer
+    # Expect NO replacement, should not rewrite misspelled file-previe URL
+    assert out == original
+
+
+def test_image_preview_valid_replaced():
+    """
+    Valid image-preview URL must be re-signed.
+    """
+    upload_id = "img-789"
+    url = f"/files/{upload_id}/image-preview?timestamp=123&nonce=456&sign=789"
+    msg = Message(answer=_wrap_md(url))
+
+    out = msg.re_sign_file_url_answer
+    assert f"https://signed.example/{upload_id}" in out
+    assert url not in out
+
+
+def test_image_preview_misspelled_not_replaced():
+    """
+    Misspelled endpoint 'image-previe?timestamp=' should NOT be rewritten.
+    """
+    upload_id = "img-err-42"
+    url = f"/files/{upload_id}/image-previe?timestamp=1&nonce=2&sign=3&note=image-preview"
+    original = _wrap_md(url)
+    msg = Message(answer=original)
+
+    out = msg.re_sign_file_url_answer
+    # Expect NO replacement, should not rewrite misspelled image-previe URL
+    assert out == original