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_read_note_pure_tool.py

@@ -0,0 +1,127 @@
+# 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.context import ArtemisContext
+from artemis.tools.base import ArtemisTool, ToolRegistry
+from artemis.tools.scratchpad import (
+    ReadNoteArgs,
+    ReadNotePure,
+    ReadNotePureTool,
+    get_read_note_tool_pure,
+    read_note_pure,
+)
+from artemis.utils.notes import save_note_content
+import pytest
+
+
+@pytest.fixture
+def mock_ctx(tmp_path):
+    ctx = MagicMock(spec=ArtemisContext)
+    ctx.data_engine = MagicMock()
+    ctx.data_engine.base_dir = str(tmp_path)
+    return ctx
+
+
+def test_read_note_pure_tool_subclass_and_registry():
+    """Verify ReadNotePureTool is a subclass of ArtemisTool and properly registered."""
+    assert issubclass(ReadNotePureTool, ArtemisTool)
+    assert issubclass(ReadNotePure, ArtemisTool)
+    assert isinstance(read_note_pure, ArtemisTool)
+    assert isinstance(read_note_pure, ReadNotePureTool)
+
+    assert read_note_pure.name == "read_note_pure"
+    assert read_note_pure.category == "memory"
+    assert read_note_pure.args_schema == ReadNoteArgs
+
+    # Registry lookup
+    reg_tool = ToolRegistry.get("read_note_pure")
+    assert reg_tool is not None
+    assert isinstance(reg_tool, ReadNotePureTool)
+
+    # GenAI FunctionDeclaration export
+    declaration = read_note_pure.to_genai_declaration()
+    assert declaration.name == "read_note_pure"
+    assert "key" in declaration.parameters.properties
+    assert "start_line" in declaration.parameters.properties
+    assert "end_line" in declaration.parameters.properties
+
+
+@pytest.mark.asyncio
+async def test_read_note_pure_direct_execution_success(mock_ctx, tmp_path):
+    """Verify direct execution of ReadNotePureTool.execute reads saved note."""
+    save_note_content(tmp_path, "sample_pure", "line 1\nline 2\nline 3")
+
+    result = await read_note_pure.execute(ctx=mock_ctx, key="sample_pure")
+    assert "Successfully read note 'sample_pure'." in result
+    assert "line 1\nline 2\nline 3" in result
+
+
+@pytest.mark.asyncio
+async def test_read_note_pure_slice(mock_ctx, tmp_path):
+    """Verify reading a line slice with start_line and end_line via ReadNotePureTool."""
+    save_note_content(tmp_path, "slice_pure", "line 1\nline 2\nline 3\nline 4")
+
+    result = await read_note_pure.execute(
+        ctx=mock_ctx,
+        key="slice_pure",
+        start_line=2,
+        end_line=3,
+    )
+    assert "Successfully read note 'slice_pure' (lines 2 to 3)." in result
+    assert "line 1" not in result
+    assert "line 2\nline 3" in result
+    assert "line 4" not in result
+
+
+@pytest.mark.asyncio
+async def test_read_note_pure_callable_execution(mock_ctx, tmp_path):
+    """Verify invoking read_note_pure directly as a callable."""
+    save_note_content(tmp_path, "callable_pure", "hello from pure callable")
+
+    result = await read_note_pure(ctx=mock_ctx, key="callable_pure")
+    assert "Successfully read note 'callable_pure'." in result
+    assert "hello from pure callable" in result
+
+
+@pytest.mark.asyncio
+async def test_read_note_pure_not_found(mock_ctx):
+    """Verify error handling when note is missing."""
+    result = await read_note_pure.execute(ctx=mock_ctx, key="nonexistent_pure")
+    assert "Note 'nonexistent_pure' not found" in result
+
+
+@pytest.mark.asyncio
+async def test_read_note_pure_other_error(mock_ctx):
+    """Verify error handling when read_note_content raises an exception."""
+    with patch(
+        "artemis.tools.scratchpad.read_note_content",
+        side_effect=OSError("Disk error"),
+    ):
+        result = await read_note_pure.execute(ctx=mock_ctx, key="err_note")
+        assert "Failed to read note 'err_note': Disk error" in result
+
+
+@pytest.mark.asyncio
+async def test_get_read_note_tool_pure_langchain_ainvoke(mock_ctx, tmp_path):
+    """Verify get_read_note_tool_pure exports a LangChain tool named 'read_note'."""
+    save_note_content(tmp_path, "pure_export", "exported pure note")
+
+    pure_tool = get_read_note_tool_pure(mock_ctx)
+    assert pure_tool.name == "read_note"
+
+    result = await pure_tool.ainvoke({"key": "pure_export"})
+    assert "Successfully read note 'pure_export'." in result
+    assert "exported pure note" in result