feat: Add override context manager to ConnectionConfig

Added `conn.config.override()` method to temporarily change connection-
scoped settings. This provides the same functionality as `dj.config.override()`
but works in thread-safe mode where global config access is blocked.

Example:
    with conn.config.override(safemode=False, display_limit=50):
        # settings changed temporarily
        pass
    # settings restored

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dimitri-yatsenko

src/datajoint/connection.py

@@ -12,7 +12,7 @@
 import warnings
 from contextlib import contextmanager
 from pathlib import Path
-from typing import Any, Callable
+from typing import Any, Callable, Iterator
 
 from . import errors
 from .adapters import get_adapter
@@ -175,6 +175,52 @@ def get_store_spec(self, store_name: str) -> dict:
             raise errors.DataJointError(f"Store '{store_name}' is not configured.")
         return stores[store_name]
 
+    @contextmanager
+    def override(self, **kwargs: Any) -> Iterator["ConnectionConfig"]:
+        """
+        Temporarily override configuration values for this connection.
+
+        Parameters
+        ----------
+        **kwargs : Any
+            Settings to override.
+
+        Yields
+        ------
+        ConnectionConfig
+            The config instance with overridden values.
+
+        Examples
+        --------
+        >>> with conn.config.override(safemode=False, display_limit=50):
+        ...     # conn.config.safemode is False here
+        ...     pass
+        >>> # conn.config.safemode is restored
+        """
+        from copy import deepcopy
+
+        # Save original values
+        backup = {}
+        for key, value in kwargs.items():
+            if key in self._values:
+                backup[key] = deepcopy(self._values[key])
+            elif key in self._DEFAULTS:
+                backup[key] = None  # Marker for "was not set"
+
+        try:
+            # Apply overrides
+            for key, value in kwargs.items():
+                self._values[key] = value
+            yield self
+        finally:
+            # Restore original values
+            for key, original in backup.items():
+                if original is None:
+                    # Was not set before, remove it
+                    self._values.pop(key, None)
+                else:
+                    self._values[key] = original
+
 
 def translate_query_error(client_error: Exception, query: str, adapter) -> Exception:
     """

tests/unit/test_thread_safe.py

@@ -355,6 +355,42 @@ def test_repr(self):
         assert "ConnectionConfig" in r
         assert "safemode=False" in r
 
+    def test_override_context_manager(self):
+        """override temporarily changes values and restores them."""
+        cfg = ConnectionConfig(safemode=True, display_limit=10)
+
+        with cfg.override(safemode=False, display_limit=50):
+            assert cfg.safemode is False
+            assert cfg.display_limit == 50
+
+        assert cfg.safemode is True
+        assert cfg.display_limit == 10
+
+    def test_override_restores_on_exception(self):
+        """override restores values even when exception is raised."""
+        cfg = ConnectionConfig(safemode=True)
+
+        try:
+            with cfg.override(safemode=False):
+                assert cfg.safemode is False
+                raise RuntimeError("test error")
+        except RuntimeError:
+            pass
+
+        assert cfg.safemode is True
+
+    def test_override_with_defaults(self):
+        """override works when value was not explicitly set."""
+        cfg = ConnectionConfig()  # Uses defaults
+        assert cfg.safemode is True  # default
+
+        with cfg.override(safemode=False):
+            assert cfg.safemode is False
+
+        # Should restore to default (not be in _values)
+        assert cfg.safemode is True
+        assert "safemode" not in cfg._values
+
 
 class TestConnectionConfigAttribute:
     """Tests for Connection.config attribute."""