Mock OpenAI model in tests to prevent real API client construction

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: John-Lin

tests/test_agents.py

@@ -1,10 +1,21 @@
 from __future__ import annotations
 
+from unittest.mock import create_autospec
+
+import pytest
+from agents.models.interface import Model
+
 from bot.agents import DEFAULT_INSTRUCTIONS
 from bot.agents import MAX_TURNS
 from bot.agents import OpenAIAgent
 
 
+@pytest.fixture(autouse=True)
+def _mock_model(monkeypatch):
+    """Prevent tests from constructing a real OpenAI client."""
+    monkeypatch.setattr("bot.agents._get_model", lambda: create_autospec(Model))
+
+
 class TestPerChatConversations:
     def test_separate_chats_have_independent_history(self):
         """Different chat_ids should maintain separate message histories."""