From 983af306b0758acf8f03d219d2d769d4d588d317 Mon Sep 17 00:00:00 2001
From: Bartok9 <danielrpike9@gmail.com>
Date: Sat, 25 Jul 2026 01:54:13 -0400
Subject: [PATCH] fix(communication): require positive callback_max_workers

ThreadPoolExecutor rejects non-positive max_workers with a generic error.
Validate callback_max_workers as a positive int up front on BaseConnector.

Signed-off-by: Bartok9 <danielrpike9@gmail.com>
---
 .../rai/communication/base_connector.py       | 10 +++++
 .../test_base_connector_workers.py            | 43 +++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 tests/communication/test_base_connector_workers.py

diff --git a/src/rai_core/rai/communication/base_connector.py b/src/rai_core/rai/communication/base_connector.py
index 51fd2f044..64590b1ea 100644
--- a/src/rai_core/rai/communication/base_connector.py
+++ b/src/rai_core/rai/communication/base_connector.py
@@ -72,6 +72,16 @@ class ParametrizedCallback(BaseModel, Generic[T]):
 
 class BaseConnector(Generic[T]):
     def __init__(self, callback_max_workers: int = 4):
+        if not isinstance(callback_max_workers, int) or isinstance(
+            callback_max_workers, bool
+        ):
+            raise ValueError(
+                f"callback_max_workers must be a positive int, got {callback_max_workers!r}"
+            )
+        if callback_max_workers <= 0:
+            raise ValueError(
+                f"callback_max_workers must be a positive int, got {callback_max_workers!r}"
+            )
         self.callback_max_workers = callback_max_workers
         self.logger = logging.getLogger(self.__class__.__name__)
         self.registered_callbacks: Dict[str, Dict[str, ParametrizedCallback[T]]] = (
diff --git a/tests/communication/test_base_connector_workers.py b/tests/communication/test_base_connector_workers.py
new file mode 100644
index 000000000..01390e144
--- /dev/null
+++ b/tests/communication/test_base_connector_workers.py
@@ -0,0 +1,43 @@
+# Copyright (C) 2025 Robotec.AI
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+from rai.communication.base_connector import BaseConnector, BaseMessage
+
+
+class _Msg(BaseMessage):
+    pass
+
+
+class _Conn(BaseConnector[_Msg]):
+    def send_message(self, message, target, **kwargs):
+        pass
+
+    def receive_message(self, source, timeout_sec, **kwargs):
+        pass
+
+    def service_call(self, message, target, timeout_sec, **kwargs):
+        pass
+
+
+@pytest.mark.parametrize("bad", [0, -1, 1.5, True, "4", None])
+def test_callback_max_workers_rejects_non_positive(bad):
+    with pytest.raises(ValueError, match="callback_max_workers must be a positive int"):
+        _Conn(callback_max_workers=bad)  # type: ignore[arg-type]
+
+
+def test_callback_max_workers_accepts_positive():
+    c = _Conn(callback_max_workers=2)
+    assert c.callback_max_workers == 2
+    c.callback_executor.shutdown(wait=False)