diff --git a/main.py b/main.py
index dd16d7f..1b69674 100644
--- a/main.py
+++ b/main.py
@@ -882,9 +882,20 @@ def require_gateway_execution_backend():
     )
 
 
-def connect_ib(*, validate_trading_permissions: bool = True):
+def connect_ib(
+    *,
+    read_only: bool = False,
+    validate_trading_permissions: bool = True,
+):
+    """Connect to the Gateway with an optional read-only session boundary."""
     require_gateway_execution_backend()
-    return build_broker_adapters().connect_ib(
+    # A probe must not merely skip the local what-if permission check.  Its
+    # Gateway session itself must be read-only, so a future probe change cannot
+    # accidentally acquire broker write authority.
+    adapter_dry_run_override = True if read_only else None
+    return build_broker_adapters(
+        dry_run_only_override=adapter_dry_run_override,
+    ).connect_ib(
         validate_trading_permissions=validate_trading_permissions,
     )
 
@@ -1735,7 +1746,10 @@ def _handle_probe(*, response_body: str = "Probe OK"):
             http_method=request.method,
             execution_window="probe",
         )
-        ib = connect_ib(validate_trading_permissions=False)
+        ib = connect_ib(
+            read_only=True,
+            validate_trading_permissions=False,
+        )
         snapshot = build_portfolio_snapshot(ib)
         positions = tuple(getattr(snapshot, "positions", ()) or ())
         buying_power = float(getattr(snapshot, "buying_power", 0.0) or 0.0)
diff --git a/tests/test_event_loop.py b/tests/test_event_loop.py
index 34d9073..984bc15 100644
--- a/tests/test_event_loop.py
+++ b/tests/test_event_loop.py
@@ -51,6 +51,22 @@ def fake_ibkr_connect(host, port, client_id, **kwargs):
     assert observed["args"] == ("127.0.0.1", 4001, 1, {"timeout": 60, "readonly": False})
 
 
+def test_live_runtime_can_force_a_read_only_gateway_session(strategy_module_factory, monkeypatch):
+    module = strategy_module_factory(IBKR_DRY_RUN_ONLY="false")
+    observed = {}
+
+    def fake_ibkr_connect(host, port, client_id, **kwargs):
+        observed["args"] = (host, port, client_id, kwargs)
+        return object()
+
+    monkeypatch.setattr(module, "ibkr_connect_ib", fake_ibkr_connect)
+
+    adapters = module.build_broker_adapters(dry_run_only_override=True)
+    adapters.connect_ib_fn("127.0.0.1", 4001, 1, timeout=60)
+
+    assert observed["args"] == ("127.0.0.1", 4001, 1, {"timeout": 60, "readonly": True})
+
+
 def test_connect_ib_retries_with_offset_client_ids(strategy_module_factory, monkeypatch):
     module = strategy_module_factory(
         IBKR_CONNECT_ATTEMPTS="3",
diff --git a/tests/test_request_handling.py b/tests/test_request_handling.py
index e8e2c1b..cbf74fb 100644
--- a/tests/test_request_handling.py
+++ b/tests/test_request_handling.py
@@ -562,8 +562,13 @@ def disconnect(self):
         "attach_strategy_plugin_report",
         lambda *args, **kwargs: (_ for _ in ()).throw(AssertionError("health probe should not attach strategy plugin reports")),
     )
-    def fake_connect_ib(*, validate_trading_permissions=True):
-        observed["connection_options"].append(validate_trading_permissions)
+    def fake_connect_ib(*, read_only=False, validate_trading_permissions=True):
+        observed["connection_options"].append(
+            {
+                "read_only": read_only,
+                "validate_trading_permissions": validate_trading_permissions,
+            }
+        )
         return FakeIB()
 
     monkeypatch.setattr(strategy_module, "connect_ib", fake_connect_ib)
@@ -589,7 +594,9 @@ def fake_connect_ib(*, validate_trading_permissions=True):
     assert observed["report"]["summary"]["positions_count"] == 1
     assert observed["disconnects"] == 1
     assert observed["notifications"] == []
-    assert observed["connection_options"] == [False]
+    assert observed["connection_options"] == [
+        {"read_only": True, "validate_trading_permissions": False}
+    ]
 
 
 def test_handle_probe_connect_timeout_sends_concise_connection_notification(strategy_module, monkeypatch):