[claude] Document and validate AirLLM Apple Silicon requirements (#1284) (#1298)

tests/unit/test_airllm_backend.py

@@ -0,0 +1,135 @@
+"""Unit tests for AirLLM backend graceful degradation.
+
+Verifies that setting TIMMY_MODEL_BACKEND=airllm on non-Apple-Silicon hardware
+(Intel Mac, Linux, Windows) or when the airllm package is not installed
+falls back to the Ollama backend without crashing.
+
+Refs #1284
+"""
+
+import sys
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+pytestmark = pytest.mark.unit
+
+
+class TestIsAppleSilicon:
+    """is_apple_silicon() correctly identifies the host platform."""
+
+    def test_returns_true_on_arm64_darwin(self):
+        from timmy.backends import is_apple_silicon
+
+        with patch("platform.system", return_value="Darwin"), patch(
+            "platform.machine", return_value="arm64"
+        ):
+            assert is_apple_silicon() is True
+
+    def test_returns_false_on_intel_mac(self):
+        from timmy.backends import is_apple_silicon
+
+        with patch("platform.system", return_value="Darwin"), patch(
+            "platform.machine", return_value="x86_64"
+        ):
+            assert is_apple_silicon() is False
+
+    def test_returns_false_on_linux(self):
+        from timmy.backends import is_apple_silicon
+
+        with patch("platform.system", return_value="Linux"), patch(
+            "platform.machine", return_value="x86_64"
+        ):
+            assert is_apple_silicon() is False
+
+    def test_returns_false_on_windows(self):
+        from timmy.backends import is_apple_silicon
+
+        with patch("platform.system", return_value="Windows"), patch(
+            "platform.machine", return_value="AMD64"
+        ):
+            assert is_apple_silicon() is False
+
+
+class TestAirLLMGracefulDegradation:
+    """create_timmy(backend='airllm') falls back to Ollama on unsupported platforms."""
+
+    def _make_fake_ollama_agent(self):
+        """Return a lightweight stub that satisfies the Agno Agent interface."""
+        agent = MagicMock()
+        agent.run = MagicMock(return_value=MagicMock(content="ok"))
+        return agent
+
+    def test_falls_back_to_ollama_on_non_apple_silicon(self, caplog):
+        """On Intel/Linux, airllm backend logs a warning and creates an Ollama agent."""
+        import logging
+
+        from timmy.agent import create_timmy
+
+        fake_agent = self._make_fake_ollama_agent()
+
+        with (
+            patch("timmy.backends.is_apple_silicon", return_value=False),
+            patch("timmy.agent._create_ollama_agent", return_value=fake_agent) as mock_create,
+            patch("timmy.agent._resolve_model_with_fallback", return_value=("qwen3:8b", False)),
+            patch("timmy.agent._check_model_available", return_value=True),
+            patch("timmy.agent._build_tools_list", return_value=[]),
+            patch("timmy.agent._build_prompt", return_value="test prompt"),
+            caplog.at_level(logging.WARNING, logger="timmy.agent"),
+        ):
+            result = create_timmy(backend="airllm")
+
+        assert result is fake_agent
+        mock_create.assert_called_once()
+        assert "Apple Silicon" in caplog.text
+
+    def test_falls_back_to_ollama_when_airllm_not_installed(self, caplog):
+        """When the airllm package is missing, log a warning and use Ollama."""
+        import logging
+
+        from timmy.agent import create_timmy
+
+        fake_agent = self._make_fake_ollama_agent()
+
+        # Simulate Apple Silicon + missing airllm package
+        def _import_side_effect(name, *args, **kwargs):
+            if name == "airllm":
+                raise ImportError("No module named 'airllm'")
+            return original_import(name, *args, **kwargs)
+
+        original_import = __builtins__["__import__"] if isinstance(__builtins__, dict) else __import__
+
+        with (
+            patch("timmy.backends.is_apple_silicon", return_value=True),
+            patch("builtins.__import__", side_effect=_import_side_effect),
+            patch("timmy.agent._create_ollama_agent", return_value=fake_agent) as mock_create,
+            patch("timmy.agent._resolve_model_with_fallback", return_value=("qwen3:8b", False)),
+            patch("timmy.agent._check_model_available", return_value=True),
+            patch("timmy.agent._build_tools_list", return_value=[]),
+            patch("timmy.agent._build_prompt", return_value="test prompt"),
+            caplog.at_level(logging.WARNING, logger="timmy.agent"),
+        ):
+            result = create_timmy(backend="airllm")
+
+        assert result is fake_agent
+        mock_create.assert_called_once()
+        assert "airllm" in caplog.text.lower() or "AirLLM" in caplog.text
+
+    def test_airllm_backend_does_not_raise(self):
+        """create_timmy(backend='airllm') never raises — it degrades gracefully."""
+        from timmy.agent import create_timmy
+
+        fake_agent = self._make_fake_ollama_agent()
+
+        with (
+            patch("timmy.backends.is_apple_silicon", return_value=False),
+            patch("timmy.agent._create_ollama_agent", return_value=fake_agent),
+            patch("timmy.agent._resolve_model_with_fallback", return_value=("qwen3:8b", False)),
+            patch("timmy.agent._check_model_available", return_value=True),
+            patch("timmy.agent._build_tools_list", return_value=[]),
+            patch("timmy.agent._build_prompt", return_value="test prompt"),
+        ):
+            # Should not raise under any circumstances
+            result = create_timmy(backend="airllm")
+
+        assert result is not None