Pin RETURNING and multivalues-insert flags locally on DqliteDialect

The SQLAlchemy 2.x tripartite RETURNING flags (insert_returning /
update_returning / delete_returning) and supports_multivalues_insert
were inherited silently from SQLiteDialect. Dqlite runs SQLite >= 3.35,
so both RETURNING and multi-row INSERT VALUES are genuinely supported,
but leaving the flags inherited means an upstream change to SQLiteDialect
(e.g. version-gated discovery) could silently alter dqlite behaviour.
Pin the four flags locally, matching the existing precedent for
supports_native_boolean, supports_sane_isolation_level, and
supports_native_decimal. Pin tests assert both the value and that the
declaration lives in DqliteDialect.__dict__ so inheritance drift is
caught.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/sqlalchemydqlite/base.py

@@ -96,6 +96,20 @@ class DqliteDialect(SQLiteDialect):
     # inherited default, pinned here against upstream drift).
     supports_native_decimal = False
 
+    # dqlite runs SQLite >= 3.35, which supports the RETURNING clause on
+    # INSERT / UPDATE / DELETE. Pin locally so upstream changes to
+    # SQLiteDialect's RETURNING detection (e.g. version-gated discovery)
+    # can't silently change dqlite behaviour. All three of SQLAlchemy 2.x's
+    # tripartite RETURNING flags default to True on the parent class today.
+    insert_returning = True
+    update_returning = True
+    delete_returning = True
+
+    # SQLite >= 3.7.11 supports multi-row INSERT VALUES, which SQLAlchemy's
+    # insertmanyvalues optimisation depends on. Pin the flag so bulk-insert
+    # behaviour stays stable against upstream dialect drift.
+    supports_multivalues_insert = True
+
     # Override the SQLite dialect's string-based DATE/DATETIME processors:
     # dqlitedbapi returns datetime objects (PEP 249), not ISO strings.
     colspecs = {

tests/test_dialect.py

@@ -53,6 +53,23 @@ def test_supports_native_decimal_false(self) -> None:
         # SQLite/dqlite has no native DECIMAL type.
         assert DqliteDialect.supports_native_decimal is False
 
+    def test_returning_flags_pinned_locally(self) -> None:
+        # dqlite runs SQLite >= 3.35, so RETURNING is supported. Pin the
+        # three SQLAlchemy 2.x flags locally so upstream dialect changes
+        # cannot silently alter dqlite behaviour.
+        assert DqliteDialect.insert_returning is True
+        assert DqliteDialect.update_returning is True
+        assert DqliteDialect.delete_returning is True
+        # Locally declared (not just inherited) so the pin is load-bearing.
+        assert "insert_returning" in DqliteDialect.__dict__
+        assert "update_returning" in DqliteDialect.__dict__
+        assert "delete_returning" in DqliteDialect.__dict__
+
+    def test_supports_multivalues_insert_pinned_locally(self) -> None:
+        # SQLite >= 3.7.11 supports multi-row INSERT VALUES; dqlite does too.
+        assert DqliteDialect.supports_multivalues_insert is True
+        assert "supports_multivalues_insert" in DqliteDialect.__dict__
+
     def test_dialect_description(self) -> None:
         # Pin the derived dialect_description so SQLAlchemy upgrades cannot
         # silently change the rendered identity in ORM error messages.