chore: cap SQLAlchemy below 2.2 and record the shared mypy pin

pyproject.toml

@@ -17,7 +17,9 @@ dependencies = [
   "psutil==7.2.2",
   "psycopg[binary]>=3.2,<4.0",
   "pyarrow==25.0.0",
-  "sqlalchemy>=2.0,<3.0",
+  # Capped below the next minor, not the next major: SQLAlchemy 2.1 retyped `Result`,
+  # which failed the type gate, so moving past 2.1 is a deliberate bump.
+  "sqlalchemy>=2.0,<2.2",
   "tzdata==2026.3",
   "uvicorn==0.52.1",
 ]
@@ -38,6 +40,7 @@ test = [
 ]
 dev = [
   "idea2strategy-backtest-engine[test]",
+  # The same release data-pipeline pins, so the two type gates agree. Bump both together.
   "mypy==2.3.0",
   "mutmut==3.3.1",
   "ruff==0.16.1",

src/backtest_engine/backtest_request_intake.py

@@ -408,7 +408,7 @@ def claim(
                 )
                 return RequestClaim(RequestClaimDisposition.CLAIMED)
 
-            latest = connection.execute(
+            latest: int = connection.execute(
                 text(
                     """
                     SELECT COALESCE(MAX(o.aggregate_sequence), 0)

tests/persistence/test_money_precision.py

@@ -75,7 +75,7 @@ def test_numeric_24_8_round_trips_without_precision_loss(persistence: BacktestPe
     with persistence.unit_of_work() as uow:
         stored = uow.runs.get(row.id).initial_cash_amount
         # `==` on Decimal ignores trailing zeros, so read the stored digits as text too.
-        stored_text = uow.connection.execute(
+        stored_text: str = uow.connection.execute(
             text("SELECT initial_cash_amount::text FROM backtest.runs WHERE id = :id"),
             {"id": str(row.id)},
         ).scalar_one()

tests/persistence/test_runtime_no_ddl.py

@@ -167,6 +167,6 @@ def test_ddl_really_did_not_happen(persistence: BacktestPersistence, admin_engin
         uow.connection.execute(text("CREATE TABLE backtest.sneaky (id uuid PRIMARY KEY)"))
 
     with admin_engine.connect() as connection:
-        exists = connection.execute(text("SELECT to_regclass('backtest.sneaky') IS NOT NULL")).scalar_one()
+        exists: bool = connection.execute(text("SELECT to_regclass('backtest.sneaky') IS NOT NULL")).scalar_one()
 
     assert exists is False