feat: add portfolio snapshot read layer

tests/application/test_snapshot_scheduler.py

@@ -0,0 +1,61 @@
+"""Snapshot scheduler tests (REQ-030 AC-1)."""
+from __future__ import annotations
+
+from trex_core.adapters.broker.paper import PaperBroker
+from trex_core.adapters.portfolio.stub_read import StubPortfolioRead
+from trex_core.application.portfolio import PortfolioItem, SnapshotStore
+from trex_core.application.snapshot_scheduler import SnapshotScheduler
+
+
+def test_run_once_fetches_universe_and_swaps_store():
+    read = StubPortfolioRead(daemon_id="d-1", items=[
+        PortfolioItem(portfolio_id="pf-X", symbol="X",
+                      cash_balance=100, asset_quantity=0),
+    ])
+    store = SnapshotStore()
+    sched = SnapshotScheduler(read_port=read, store=store, broker=PaperBroker())
+    assert sched.run_once() is True
+    pids = {a.item.portfolio_id for a in store.list_assets()}
+    assert pids == {"pf-X"}
+    # universe membership + strategy params come from fetch (baseline)
+    # cash/quantity are baseline values (option D will overwrite later)
+    a = store.get("pf-X")
+    assert a.item.cash_balance == 100
+    assert a.warning is False
+
+
+def test_run_once_failure_sets_degraded_signal():
+    class BadRead:
+        def whoami(self): return "d-2"
+        def get_portfolios(self, daemon_id):
+            from trex_core.application.portfolio import PortfolioHubUnavailableError
+            raise PortfolioHubUnavailableError("simulated")
+    store = SnapshotStore()
+    sched = SnapshotScheduler(read_port=BadRead(), store=store, broker=PaperBroker())
+    assert sched.run_once() is False
+    reason, msg = store.degraded_state()
+    assert reason is not None and reason.value == "portfolio_hub_unavailable"
+
+
+def test_swap_preserves_warning_for_carried_over_portfolio():
+    store = SnapshotStore()
+    store.swap([PortfolioItem(portfolio_id="pf-X", symbol="X",
+                              cash_balance=100, asset_quantity=0)])
+    store.set_warning("pf-X", True)
+    # second swap includes the same portfolio with refreshed cash
+    store.swap([PortfolioItem(portfolio_id="pf-X", symbol="X",
+                              cash_balance=200, asset_quantity=0)])
+    a = store.get("pf-X")
+    assert a.warning is True
+    assert a.item.cash_balance == 200
+
+
+def test_option_d_update_cash_position_overrides_baseline():
+    """REQ-030 wiring — when *_after lands we update the authoritative values."""
+    store = SnapshotStore()
+    store.swap([PortfolioItem(portfolio_id="pf-X", symbol="X",
+                              cash_balance=100, asset_quantity=0)])
+    store.update_cash_position("pf-X", cash_balance=92.5, asset_quantity=1)
+    a = store.get("pf-X")
+    assert a.item.cash_balance == 92.5
+    assert a.item.asset_quantity == 1