Split exchange and strategy modules for future Binance support.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/main.py

@@ -11,9 +11,9 @@ from fastapi.staticfiles import StaticFiles
 
 from .api import router as api_router
 from .config import get_settings
-from .market import MarketGateway, set_gateway
 from .models.db import Database, set_db
 from .strategy import StrategyEngine, set_engine
+from .strategy.session import bootstrap_session
 
 logging.basicConfig(
     level=logging.INFO,
@@ -36,13 +36,15 @@ async def lifespan(app: FastAPI):
     engine = StrategyEngine()
     set_engine(engine)
 
-    gw = MarketGateway(settings)
-    set_gateway(gw)
+    session = bootstrap_session(settings)
     try:
-        await gw.start()
-        logger.info("market gateway started (SIM)")
+        await session.start()
+        logger.info(
+            "exchange=%s strategy session started (SIM)",
+            settings.exchange,
+        )
     except Exception:
-        logger.exception("market gateway failed to start")
+        logger.exception("strategy session failed to start")
 
     yield
 
@@ -53,8 +55,12 @@ async def lifespan(app: FastAPI):
             await engine._task
         except Exception:
             pass
-    await gw.stop()
-    set_gateway(None)
+    await session.stop()
+    from .exchange import set_exchange
+    from .strategy.session import set_session
+
+    set_session(None)
+    set_exchange(None)
     set_engine(None)
     db.close()
     set_db(None)
@@ -78,12 +84,12 @@ app.include_router(api_router)
 
 @app.get("/health")
 async def health() -> dict:
-    from .market import get_gateway
     from .strategy import get_engine
+    from .strategy.session import get_session
 
     settings = get_settings()
-    gw = get_gateway()
-    snap = gw.snapshot()
+    sess = get_session()
+    snap = sess.snapshot()
     try:
         st = get_engine().state()
     except Exception:
@@ -92,6 +98,7 @@ async def health() -> dict:
         "ok": True,
         "mode": settings.mode,
         "env_name": settings.env_name,
+        "exchange": settings.exchange,
         "sim": settings.is_sim,
         "market_connected": snap.connected,
         "pair": snap.pair.to_dict() if snap.pair else None,