test(core): Replace pytest.fail with functional assertions in token_usage and agent_capabilities

tests/test_agent_capabilities.py

@@ -1,10 +1,43 @@
 import pytest
 import sys
 import os
+from unittest.mock import patch, MagicMock
 
 # Ensure project root is in path
 sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
 
+import ai_client
 
 def test_agent_capabilities_listing() -> None:
- pytest.fail("TODO: Implement assertions")
+ # Mock credentials
+ with patch("ai_client._load_credentials") as mock_creds:
+  mock_creds.return_value = {"gemini": {"api_key": "fake-key"}}
+  
+  # Mock the google-genai Client and models.list
+  with patch("google.genai.Client") as mock_client_class:
+   mock_client = mock_client_class.return_value
+   
+   # Create a list of mock models
+   mock_models = []
+   model_names = [
+    "models/gemini-2.0-flash",
+    "models/gemini-2.0-flash-lite",
+    "models/gemini-1.5-pro",
+    "models/gemini-1.5-flash",
+    "models/gemini-pro",
+    "models/gemini-ultra"
+   ]
+   for name in model_names:
+    m = MagicMock()
+    m.name = name
+    mock_models.append(m)
+   
+   mock_client.models.list.return_value = mock_models
+   
+   models = ai_client.list_models("gemini")
+   
+   assert len(models) >= 6
+   assert "gemini-2.0-flash" in models
+   # Check that it stripped "models/" prefix
+   for m in models:
+    assert not m.startswith("models/")