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/tools/log_analyzer/test_log_analyzer_tools.py

@@ -0,0 +1,61 @@
+# 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 artemis.agents.log_analyzer.log_analyzer import LogAnalyzerNode
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_spawn_log_reader(artemis_context, mock_state):
+    """Test the spawn_log_reader tool exposed by LogAnalyzerNode."""
+    from artemis.sdk.utils import load_llm_config_override
+    from pathlib import Path
+
+    node = LogAnalyzerNode(ctx=artemis_context)
+    artemis_context.llm_config = load_llm_config_override(Path("llm-config.json"))
+    if artemis_context.data_engine:
+        artemis_context.data_engine.start_session("test_session")
+    tool = node._get_spawn_log_reader_tool()
+
+    # Let the tool run its lifecycle. It will use the real LLM APIs.
+    # Note: State injection is normally handled by LangGraph/tool invocation,
+    # but since we are testing the coroutine directly, we can pass it manually.
+    result = await tool.coroutine(
+        specific_query=("Find any errors related to network timeout in the logs."),
+        state=mock_state,
+    )
+
+    assert result is not None
+    assert isinstance(result, (str, list))
+    assert len(result) > 0
+
+
+@pytest.mark.asyncio
+async def test_log_analyzer_run(artemis_context, mock_state):
+    """Test LogAnalyzerNode.run end-to-end execution with grounding configuration."""
+    from artemis.config.llm import parse_llm_config
+
+    node = LogAnalyzerNode(ctx=artemis_context)
+    artemis_context.llm_config = parse_llm_config()
+    if artemis_context.data_engine:
+        artemis_context.data_engine.start_session("test_log_analyzer_session")
+
+    result = await node.run(
+        prompt="Analyze recent error logs for potential crash or exception tags.",
+        state=mock_state,
+    )
+
+    assert result is not None
+    assert isinstance(result, (str, list))
+    assert len(result) > 0