fix(#532): align window total schema mapping (#541)

## Summary

Closes #532.

- Route `select_with_total(count_with_window=True)` window rows through
the normal schema conversion path in both sync and async drivers.
- Keep `_add_count_over_column()` and `_extract_total_from_rows()`
unchanged; the generated SQL was already correct.
- Add sync SQLite and async aiosqlite regressions for `msgspec.Struct`
schemas that omit an extra selected column.

## Root Cause

The two-query path used `SQLResult.get_data(schema_type=...)`, but the
window-count path stripped `_total_count` and then constructed schema
objects directly with `schema_type(**row)`. Direct `msgspec.Struct`
construction rejects unmapped columns, while the normal SQLSpec
conversion path tolerates them.

Author: cofin

sqlspec/driver/_async.py

@@ -1154,7 +1154,7 @@ async def select_with_total(
             data, total = self._extract_total_from_rows(rows)
 
             if schema_type is not None:
-                return ([schema_type(**r) for r in data], total)
+                return (cast("list[SchemaT]", self.to_schema(data, schema_type=schema_type)), total)
             return (data, total)
 
         count_result = await self.dispatch_statement_execution(self._create_count_query(sql_statement), self.connection)

sqlspec/driver/_sync.py

@@ -1143,7 +1143,7 @@ def select_with_total(
             data, total = self._extract_total_from_rows(rows)
 
             if schema_type is not None:
-                return ([schema_type(**r) for r in data], total)
+                return (cast("list[SchemaT]", self.to_schema(data, schema_type=schema_type)), total)
             return (data, total)
 
         count_result = self.dispatch_statement_execution(self._create_count_query(sql_statement), self.connection)

tests/unit/driver/test_count_query.py

@@ -8,6 +8,7 @@
 from types import SimpleNamespace
 from typing import Any
 
+import msgspec
 import pytest
 
 from sqlspec import SQL
@@ -656,6 +657,80 @@ def test_select_with_total_window_count_handles_repeated_named_parameters(sqlite
     assert [row["id"] for row in rows] == [1, 2]
 
 
+def test_select_with_total_window_count_uses_schema_conversion_for_extra_columns(sqlite_driver: "SqliteDriver") -> None:
+    """Window-count pagination should map rows through the normal schema converter."""
+
+    class Item(msgspec.Struct):
+        id: int
+        name: str
+
+    sqlite_driver.connection.executescript("""
+        CREATE TABLE window_schema_items (
+            id INTEGER PRIMARY KEY,
+            name TEXT,
+            extra_col TEXT
+        );
+        INSERT INTO window_schema_items (id, name, extra_col) VALUES (1, 'a', 'x');
+        INSERT INTO window_schema_items (id, name, extra_col) VALUES (2, 'b', 'x');
+        INSERT INTO window_schema_items (id, name, extra_col) VALUES (3, 'c', 'y');
+    """)
+
+    rows, total = sqlite_driver.select_with_total(
+        """
+        SELECT id, name, extra_col
+        FROM window_schema_items
+        ORDER BY id
+        LIMIT 2
+        """,
+        schema_type=Item,
+        count_with_window=True,
+    )
+
+    assert total == 3
+    assert rows == [Item(id=1, name="a"), Item(id=2, name="b")]
+
+
+@pytest.mark.anyio
+async def test_async_select_with_total_window_count_uses_schema_conversion_for_extra_columns() -> None:
+    """Async window-count pagination should map rows through the normal schema converter."""
+
+    from sqlspec.adapters.aiosqlite import AiosqliteConfig
+
+    class Item(msgspec.Struct):
+        id: int
+        name: str
+
+    config = AiosqliteConfig()
+    try:
+        async with config.provide_session() as driver:
+            await driver.execute_script("""
+                CREATE TABLE async_window_schema_items (
+                    id INTEGER PRIMARY KEY,
+                    name TEXT,
+                    extra_col TEXT
+                );
+                INSERT INTO async_window_schema_items (id, name, extra_col) VALUES (1, 'a', 'x');
+                INSERT INTO async_window_schema_items (id, name, extra_col) VALUES (2, 'b', 'x');
+                INSERT INTO async_window_schema_items (id, name, extra_col) VALUES (3, 'c', 'y');
+            """)
+
+            rows, total = await driver.select_with_total(
+                """
+                SELECT id, name, extra_col
+                FROM async_window_schema_items
+                ORDER BY id
+                LIMIT 2
+                """,
+                schema_type=Item,
+                count_with_window=True,
+            )
+
+        assert total == 3
+        assert rows == [Item(id=1, name="a"), Item(id=2, name="b")]
+    finally:
+        await config.close_pool()
+
+
 # =============================================================================
 # Bug Fix: Pagination Parameters Excluded from Count Query
 # =============================================================================