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_image_processor_tool.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 unittest.mock import AsyncMock, MagicMock, patch
+
+from artemis.context import ArtemisContext
+from artemis.graph.state import State
+from artemis.tools.image_processor_tool import get_ask_image_processor_tool
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_ask_vision_coder_success():
+    # Mock Context and State
+    mock_ctx = MagicMock(spec=ArtemisContext)
+    mock_ctx.data_engine = None
+
+    mock_state = MagicMock(spec=State)
+    mock_state.latest_screenshot = "/tmp/test_screen.jpg"
+
+    # Mock VisionCoder Agent Outcome
+    vision_coder_outcome = {
+        "new_image_path": "/tmp/coder_output.jpg",
+        "summary": "Found red button at pixel coords (100, 200)",
+    }
+
+    # We need to patch the ImageProcessor class inside the tool
+    mock_coder_instance = MagicMock()
+    mock_coder_instance.run = AsyncMock(return_value=vision_coder_outcome)
+
+    with patch(
+        "artemis.agents.image_processor.image_processor.ImageProcessor",
+        return_value=mock_coder_instance,
+    ):
+        # Retrieve the tool
+        ask_vision_coder_tool = get_ask_image_processor_tool(mock_ctx)
+
+        # Invoke the tool
+        result = await ask_vision_coder_tool.ainvoke(
+            {
+                "instruction": "Find the red button",
+                "target_image_id": "img_0",
+                "state": mock_state,
+            }
+        )
+
+        # Verify the agent was called with correct arguments
+        mock_coder_instance.run.assert_called_once_with(
+            "Find the red button", "/tmp/test_screen.jpg"
+        )
+
+        # Verify the output matches
+        assert result == vision_coder_outcome
+
+
+def test_ask_image_processor_tool_subclass_and_registry():
+    """Verify AskImageProcessorTool is an ArtemisTool subclass and registered in ToolRegistry."""
+    from artemis.tools.base import ArtemisTool, ToolRegistry
+    from artemis.tools.image_processor_tool import (
+        AskImageProcessor,
+        AskImageProcessorTool,
+        AskVisionCoderArgs,
+        AskVisionCoderTool,
+        ImageProcessorTool,
+        ask_image_processor,
+    )
+
+    assert issubclass(AskImageProcessorTool, ArtemisTool)
+    assert issubclass(AskImageProcessor, ArtemisTool)
+    assert issubclass(AskVisionCoderTool, ArtemisTool)
+    assert issubclass(ImageProcessorTool, ArtemisTool)
+    assert isinstance(ask_image_processor, ArtemisTool)
+    assert isinstance(ask_image_processor, AskImageProcessorTool)
+
+    assert ask_image_processor.name == "ask_image_processor"
+    assert ask_image_processor.category == "custom"
+    assert ask_image_processor.args_schema == AskVisionCoderArgs
+
+    # Registry lookup
+    reg_tool = ToolRegistry.get("ask_image_processor")
+    assert reg_tool is not None
+    assert isinstance(reg_tool, AskImageProcessorTool)
+
+    # GenAI FunctionDeclaration export
+    declaration = ask_image_processor.to_genai_declaration()
+    assert declaration.name == "ask_image_processor"
+    assert "instruction" in declaration.parameters.properties
+    assert "target_image_id" in declaration.parameters.properties