fix: require executable source for Work reports

tests/test_agent_loop.py

@@ -10,6 +10,7 @@ from agent_platform.models import get_model_spec
 from agent_platform.runtime.loop import (
     AgentLoop,
     is_substantive_execution,
+    non_source_execution_error,
     normalize_write_file_content,
     python_source_error,
     select_tool_specs,
@@ -59,6 +60,14 @@ def test_invalid_complete_python_source_is_detected_before_write() -> None:
     assert python_source_error({"path": "benchmark.py", "content": "print('ok')\n"}) is None
 
 
+def test_python_cannot_execute_documentation_or_data_files() -> None:
+    assert non_source_execution_error({"command": "python3 SortingReport.md"}) is not None
+    assert non_source_execution_error({"command": "cd /workspace && python report.json"}) is not None
+    assert non_source_execution_error({"command": "python3 benchmark.py"}) is None
+    assert non_source_execution_error({"command": "python3 -m pytest"}) is None
+    assert non_source_execution_error({"command": "python3 -c 'print(1)' "}) is None
+
+
 def test_read_only_shell_commands_do_not_satisfy_execution_evidence() -> None:
     assert not is_substantive_execution("exec", {"command": "cat report.txt"})
     assert not is_substantive_execution("exec", {"command": "sed -n '1,20p' script.py"})