diff --git a/src/fxhnt/application/combined_book_factory.py b/src/fxhnt/application/combined_book_factory.py
new file mode 100644
index 0000000..ab0bf82
--- /dev/null
+++ b/src/fxhnt/application/combined_book_factory.py
@@ -0,0 +1,12 @@
+"""Composition helper: build the CombinedBookSource the settings select (the reversible cutover seam)."""
+from __future__ import annotations
+
+from fxhnt.application.combined_book_source import CombinedBookSource, RawFileSource, WarehouseSource
+from fxhnt.config import Settings
+
+
+def make_combined_book_source(settings: Settings, data_dir: str) -> CombinedBookSource:
+    if settings.combined_book_data_source == "warehouse":
+        from fxhnt.adapters.warehouse.duckdb_feature_store import DuckDbFeatureStore
+        return WarehouseSource(DuckDbFeatureStore(settings.warehouse_path))
+    return RawFileSource(data_dir)
diff --git a/src/fxhnt/cli.py b/src/fxhnt/cli.py
index e6b7142..f6b09fa 100644
--- a/src/fxhnt/cli.py
+++ b/src/fxhnt/cli.py
@@ -210,9 +210,11 @@ def forward_track(
     """Forward-validate the combined book: book today's realized return into the paper track. Run daily on
     a cron alongside the data fetch — the forward NAV/Sharpe is the only ground truth before capital."""
     from fxhnt.application.combined_book import CombinedBook
+    from fxhnt.application.combined_book_factory import make_combined_book_source
     from fxhnt.application.forward_tracker import CombinedBookForwardTracker
 
-    book = CombinedBook(data_dir, _FUTURES_UNIVERSE)
+    book = CombinedBook(data_dir, _FUTURES_UNIVERSE,
+                        source=make_combined_book_source(get_settings(), data_dir))
     st = CombinedBookForwardTracker(book, state).step()
     typer.echo(f"forward track since {st.inception} (last {st.last_date}): {st.forward_days} forward days, "
                f"booked {st.booked_today} today")
diff --git a/src/fxhnt/config.py b/src/fxhnt/config.py
index 3bd59a2..d56e3fb 100644
--- a/src/fxhnt/config.py
+++ b/src/fxhnt/config.py
@@ -106,6 +106,9 @@ class Settings(BaseSettings):
     analytical_path: str = Field(default=str(_DATA_DIR / "analytical.duckdb"))
     # Warehouse (point-in-time SSOT: bars, funding, microstructure features) — DuckDB embedded file.
     warehouse_path: str = Field(default=str(_DATA_DIR / "warehouse.duckdb"))
+    # Combined-book data path: "raw" (crypto_pit/.dbn files) or "warehouse" (SSOT). Default raw for safety;
+    # the B0 Dagster deploy sets FXHNT_COMBINED_BOOK_DATA_SOURCE=warehouse.
+    combined_book_data_source: str = Field(default="raw")
 
     cost_bps_per_turnover: float = 10.0   # round-trip cost model (bps of traded notional)
     gauntlet: GauntletSettings = Field(default_factory=GauntletSettings)
diff --git a/tests/unit/test_combined_book_factory.py b/tests/unit/test_combined_book_factory.py
new file mode 100644
index 0000000..e90d9ac
--- /dev/null
+++ b/tests/unit/test_combined_book_factory.py
@@ -0,0 +1,16 @@
+"""The factory picks WarehouseSource vs RawFileSource from settings (combined_book_data_source)."""
+from __future__ import annotations
+
+from fxhnt.application.combined_book_factory import make_combined_book_source
+from fxhnt.application.combined_book_source import RawFileSource, WarehouseSource
+from fxhnt.config import Settings
+
+
+def test_factory_raw_default(tmp_path) -> None:
+    s = Settings(combined_book_data_source="raw", warehouse_path=str(tmp_path / "wh.duckdb"))
+    assert isinstance(make_combined_book_source(s, "/data/surfer"), RawFileSource)
+
+
+def test_factory_warehouse(tmp_path) -> None:
+    s = Settings(combined_book_data_source="warehouse", warehouse_path=str(tmp_path / "wh.duckdb"))
+    assert isinstance(make_combined_book_source(s, "/data/surfer"), WarehouseSource)