fix: address account valuation review findings

tests/test_account_basis_public_consumers.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import inspect
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
+
+from dashboard.page_views import accounts as accounts_page
+from jarca_ledger_mcp.adapters.mcp import server
+
+
+def test_dashboard_valuation_basis_never_uses_sync_timestamp():
+    account = {
+        "last_balance_basis_date": "2026-06-30",
+        "last_synced_at": "2026-07-09T23:59:00+09:00",
+    }
+    assert accounts_page._account_balance_basis_date(account) == "2026-06-30"
+    assert accounts_page._account_balance_basis_date({"last_synced_at": account["last_synced_at"]}) == ""
+    assert "last_synced_at" not in inspect.getsource(accounts_page.page_accounts)
+
+
+def test_mcp_account_write_tools_forward_explicit_balance_basis(monkeypatch):
+    calls: list[tuple[str, tuple, dict]] = []
+
+    def fake_create(*args, **kwargs):
+        calls.append(("create", args, kwargs))
+        return {"success": True}
+
+    def fake_update(*args, **kwargs):
+        calls.append(("update", args, kwargs))
+        return {"success": True}
+
+    monkeypatch.setattr(server.contracts, "create_ledger_account", fake_create)
+    monkeypatch.setattr(server.contracts, "update_ledger_account", fake_update)
+
+    assert server.create_ledger_account(
+        "dated", last_balance=100, last_synced_at="2026-07-09T00:00:00Z",
+        last_balance_basis_date="2026-06-30",
+    )["success"]
+    assert server.update_ledger_account(
+        "account-1", last_balance=200, last_synced_at="2026-07-10T00:00:00Z",
+        last_balance_basis_date="2026-07-01",
+    )["success"]
+
+    assert calls[0][2]["last_balance_basis_date"] == "2026-06-30"
+    assert calls[1][2]["last_balance_basis_date"] == "2026-07-01"