Treat grep no matches as nonfatal

tests/test_tools_flow.py

@@ -112,6 +112,23 @@ def test_shell_exec_allows_safe_command(tmp_path: Path) -> None:
     assert str(tmp_path) in result["result"]["output"]
 
 
+def test_shell_exec_treats_grep_no_matches_as_information(tmp_path: Path) -> None:
+    _write_config_tree(tmp_path)
+    controller = RuntimeController(base_dir=tmp_path)
+    result = controller.handle_task(
+        UserTask(
+            input="run grep with no matches",
+            context={
+                "requested_tool": "shell_exec",
+                "tool_args": {"command": "printf 'abc\\n' | grep definitely_missing"},
+            },
+        )
+    )
+    assert result["status"] == "completed"
+    assert result["result"]["metadata"]["exit_code"] == 1
+    assert result["result"]["metadata"]["no_matches"] is True
+
+
 def test_permission_resolution_can_resume_task(tmp_path: Path) -> None:
     _write_config_tree(tmp_path)
     controller = RuntimeController(base_dir=tmp_path)