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/diagnoser/test_diagnoser_tools.py

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+# 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.tools.diagnoser_submit_answer_tool import get_submit_answer_tool
+
+
+def test_diagnoser_submit_answer_tool(artemis_context):
+    tool = get_submit_answer_tool(artemis_context)
+
+    # Execute the tool with some typical payload
+    result = tool.invoke(
+        {
+            "analysis": "The problem is caused by a network timeout.",
+            "actionable_steps": ["Check network connection", "Restart the server"],
+        }
+    )
+
+    # Assert that the tool executes without raising errors and produces expected output structure
+    assert result == "Answer submitted successfully."
+    assert "error" not in result.lower()
+
+
+def test_submit_answer_tool_subclass_and_registry():
+    """Verify SubmitAnswerTool is an ArtemisTool subclass and registered in ToolRegistry."""
+    from artemis.tools.base import ArtemisTool, ToolRegistry
+    from artemis.tools.diagnoser_submit_answer_tool import (
+        DiagnoserSubmitAnswerTool,
+        SubmitAnswer,
+        SubmitAnswerArgs,
+        SubmitAnswerTool,
+        submit_answer,
+    )
+
+    assert issubclass(SubmitAnswerTool, ArtemisTool)
+    assert issubclass(SubmitAnswer, ArtemisTool)
+    assert issubclass(DiagnoserSubmitAnswerTool, ArtemisTool)
+    assert isinstance(submit_answer, ArtemisTool)
+    assert isinstance(submit_answer, SubmitAnswerTool)
+
+    assert submit_answer.name == "submit_answer"
+    assert submit_answer.category == "custom"
+    assert submit_answer.args_schema == SubmitAnswerArgs
+
+    # Registry lookup
+    reg_tool = ToolRegistry.get("submit_answer")
+    assert reg_tool is not None
+    assert isinstance(reg_tool, SubmitAnswerTool)
+
+    # GenAI FunctionDeclaration export
+    declaration = submit_answer.to_genai_declaration()
+    assert declaration.name == "submit_answer"
+    assert "analysis" in declaration.parameters.properties
+    assert "actionable_steps" in declaration.parameters.properties
+
+
+def test_ask_diagnoser_tool_subclass_and_registry():
+    """Verify AskDiagnoserTool is an ArtemisTool subclass and registered in ToolRegistry."""
+    from artemis.tools.base import ArtemisTool, ToolRegistry
+    from artemis.tools.diagnostic_tool import (
+        AskDiagnoser,
+        AskDiagnoserArgs,
+        AskDiagnoserTool,
+        DiagnosticTool,
+        ask_diagnoser,
+    )
+
+    assert issubclass(AskDiagnoserTool, ArtemisTool)
+    assert issubclass(AskDiagnoser, ArtemisTool)
+    assert issubclass(DiagnosticTool, ArtemisTool)
+    assert isinstance(ask_diagnoser, ArtemisTool)
+    assert isinstance(ask_diagnoser, AskDiagnoserTool)
+
+    assert ask_diagnoser.name == "ask_diagnoser"
+    assert ask_diagnoser.category == "custom"
+    assert ask_diagnoser.args_schema == AskDiagnoserArgs
+
+    # Registry lookup
+    reg_tool = ToolRegistry.get("ask_diagnoser")
+    assert reg_tool is not None
+    assert isinstance(reg_tool, AskDiagnoserTool)
+
+    # GenAI FunctionDeclaration export
+    declaration = ask_diagnoser.to_genai_declaration()
+    assert declaration.name == "ask_diagnoser"
+    assert "query" in declaration.parameters.properties
+
+
+def test_analyze_logs_tool_subclass_and_registry():
+    """Verify AnalyzeLogsTool is an ArtemisTool subclass and registered in ToolRegistry."""
+    from artemis.tools.base import ArtemisTool, ToolRegistry
+    from artemis.tools.log_tool import (
+        AnalyzeLogs,
+        AnalyzeLogsArgs,
+        AnalyzeLogsTool,
+        LogTool,
+        analyze_logs,
+    )
+
+    assert issubclass(AnalyzeLogsTool, ArtemisTool)
+    assert issubclass(AnalyzeLogs, ArtemisTool)
+    assert issubclass(LogTool, ArtemisTool)
+    assert isinstance(analyze_logs, ArtemisTool)
+    assert isinstance(analyze_logs, AnalyzeLogsTool)
+
+    assert analyze_logs.name == "analyze_logs"
+    assert analyze_logs.category == "custom"
+    assert analyze_logs.args_schema == AnalyzeLogsArgs
+
+    # Registry lookup
+    reg_tool = ToolRegistry.get("analyze_logs")
+    assert reg_tool is not None
+    assert isinstance(reg_tool, AnalyzeLogsTool)
+
+    # GenAI FunctionDeclaration export
+    declaration = analyze_logs.to_genai_declaration()
+    assert declaration.name == "analyze_logs"
+    assert "specific_query" in declaration.parameters.properties