test: add comprehensive unit, integration, and e2e test suites

Introduce complete test coverage for the ARTEMIS platform across multiple layers:
Unit tests: Add tests for agent nodes (Planner, Operator, Validator, Diagnoser, FlashRunner, Explorer), tools, utils (OCR/XML fusion, UI hierarchy), and data engine.
Integration tests: Add live tool verification, reactive runner, IME, and standalone workflow tests.
E2E tests: Add end-to-end scenario tests for media playback and failure recovery flows.
Fixtures & mocks: Add mock inputs (audio, video, screenshot) and test utilities.

tests/unit/tools/test_launch_app.py

@@ -0,0 +1,92 @@
+# Copyright 2026 Google LLC
+#
+# 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.
+
+from unittest.mock import MagicMock, patch
+from artemis.agents.hopper.hopper import HopperOutput
+from artemis.context import ArtemisContext
+from artemis.tools.mobile.launch_app import find_package
+import pytest
+
+
+@pytest.fixture
+def mock_context():
+    ctx = MagicMock(spec=ArtemisContext)
+    ctx.package_cache = {}
+    return ctx
+
+
+@pytest.mark.asyncio
+@patch("artemis.tools.mobile.launch_app.list_packages_async")
+@patch("artemis.tools.mobile.launch_app.hopper")
+async def test_find_package_cache_hit(mock_hopper, mock_list_packages, mock_context):
+    mock_list_packages.return_value = "com.example.app1\ncom.example.app2"
+
+    # First call: not in cache, calls hopper
+    mock_hopper.return_value = HopperOutput(
+        found=True, output="com.example.app1", reason="Found it"
+    )
+
+    pkg1 = await find_package(mock_context, "App 1")
+    assert pkg1 == "com.example.app1"
+    assert mock_hopper.call_count == 1
+    assert mock_context.package_cache["App 1"] == "com.example.app1"
+
+    # Second call: cache hit, does not call hopper or list_packages again
+    mock_hopper.reset_mock()
+    mock_list_packages.reset_mock()
+
+    pkg2 = await find_package(mock_context, "App 1")
+    assert pkg2 == "com.example.app1"
+    mock_hopper.assert_not_called()
+    mock_list_packages.assert_not_called()
+
+
+@pytest.mark.asyncio
+@patch("artemis.tools.mobile.launch_app.list_packages_async")
+@patch("artemis.tools.mobile.launch_app.hopper")
+async def test_find_package_not_found_caches_none(mock_hopper, mock_list_packages, mock_context):
+    mock_list_packages.return_value = "com.example.app1\ncom.example.app2"
+
+    # Hopper doesn't find it
+    mock_hopper.return_value = HopperOutput(found=False, output=None, reason="Not found")
+
+    pkg1 = await find_package(mock_context, "App 3")
+    assert pkg1 is None
+    assert mock_hopper.call_count == 1
+    assert mock_context.package_cache["App 3"] is None
+
+    # Second call: cache hit (None), does not call hopper again
+    mock_hopper.reset_mock()
+    pkg2 = await find_package(mock_context, "App 3")
+    assert pkg2 is None
+    mock_hopper.assert_not_called()
+
+
+@pytest.mark.asyncio
+@patch("artemis.tools.mobile.launch_app.list_packages_async")
+@patch("artemis.tools.mobile.launch_app.hopper")
+async def test_find_package_passes_use_fallback(mock_hopper, mock_list_packages, mock_context):
+    mock_list_packages.return_value = "com.example.app1\ncom.example.app2"
+    mock_hopper.return_value = HopperOutput(
+        found=True, output="com.example.app1", reason="Found it"
+    )
+
+    # Pass use_fallback=False
+    await find_package(mock_context, "App 1", use_fallback=False)
+    mock_hopper.assert_called_once_with(
+        ctx=mock_context,
+        request=("I'm looking for the package name of the following app: 'App 1'"),
+        data="com.example.app1\ncom.example.app2",
+        use_fallback=False,
+    )