diff --git a/src/multi_swarm/backtest/__init__.py b/src/multi_swarm/backtest/__init__.py
index e69de29..de8a85d 100644
--- a/src/multi_swarm/backtest/__init__.py
+++ b/src/multi_swarm/backtest/__init__.py
@@ -0,0 +1,13 @@
+"""Backtest layer: order/position/trade dataclasses + engine."""
+
+from .engine import BacktestEngine, BacktestResult
+from .orders import Order, Position, Side, Trade
+
+__all__ = [
+    "BacktestEngine",
+    "BacktestResult",
+    "Order",
+    "Position",
+    "Side",
+    "Trade",
+]
diff --git a/src/multi_swarm/cerbero/__init__.py b/src/multi_swarm/cerbero/__init__.py
index e69de29..2ea6160 100644
--- a/src/multi_swarm/cerbero/__init__.py
+++ b/src/multi_swarm/cerbero/__init__.py
@@ -0,0 +1,5 @@
+"""Cerbero data-provider HTTP client."""
+
+from .client import CerberoClient
+
+__all__ = ["CerberoClient"]
diff --git a/src/multi_swarm/data/__init__.py b/src/multi_swarm/data/__init__.py
index e69de29..ef0c5c1 100644
--- a/src/multi_swarm/data/__init__.py
+++ b/src/multi_swarm/data/__init__.py
@@ -0,0 +1,5 @@
+"""Data loaders: OHLCV via Cerbero, train/test splits."""
+
+from .cerbero_ohlcv import CerberoOHLCVLoader, OHLCVRequest
+
+__all__ = ["CerberoOHLCVLoader", "OHLCVRequest"]