feat: improve task execution, verification and packaging

Add execution incidents, action bursts and shared Flash history.

Expose verification and Explorer settings with streamed check results.

Support graceful cancellation, recording recovery and bundled UI resources.

Add CI quality checks and clean up comments and documentation.

tests/unit/agents/test_checker_structured_report.py

@@ -0,0 +1,55 @@
+# 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.
+
+"""The structured verdict request must never end on a model turn (Gemini
+rejects such requests with 400 "Requests ending with a model turn are not
+supported"), which is the natural state after the loop's tool-free reply."""
+
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+from langchain_core.messages import AIMessage, HumanMessage, SystemMessage
+
+from artemis.agents.checker.checker import CheckReport, _structured_report
+
+
+def _llm(report: CheckReport):
+    structured = MagicMock()
+    structured.ainvoke = AsyncMock(return_value=report)
+    llm = MagicMock()
+    llm.with_structured_output.return_value = structured
+    return llm, structured
+
+
+@pytest.mark.asyncio
+async def test_structured_report_appends_user_turn_after_model_reply():
+    llm, structured = _llm(CheckReport(verdicts=[]))
+    messages = [SystemMessage(content="s"), HumanMessage(content="h"), AIMessage(content="done")]
+
+    await _structured_report(llm, messages)
+
+    sent = structured.ainvoke.call_args.args[0]
+    assert isinstance(sent[-1], HumanMessage)
+    assert sent[-2] is messages[-1]
+    assert len(messages) == 3  # caller's list untouched
+
+
+@pytest.mark.asyncio
+async def test_structured_report_keeps_user_ending_conversation_as_is():
+    llm, structured = _llm(CheckReport(verdicts=[]))
+    messages = [SystemMessage(content="s"), HumanMessage(content="final iteration")]
+
+    await _structured_report(llm, messages)
+
+    assert structured.ainvoke.call_args.args[0] is messages