fix: validate sandbox readiness before rein handoff

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a0726e-5232-73f2-aaca-2c05ceb62efb

tests/test_gateway.py

@@ -519,3 +519,37 @@ def test_old_result_records_have_unknown_outcomes():
     assert restored.hub_report_status == 'unknown'
     assert restored.evidence.session_cleanup == 'unknown'
     assert restored.evidence.sandbox_destroy == 'unknown'
+
+
+@pytest.mark.parametrize('state', [state for state in SandboxState if state != SandboxState.READY])
+def test_nonready_owner_handoff_never_starts_rein(state):
+    manager = MagicMock()
+    manager.create.return_value = _fake_status().model_copy(update={'state': state})
+    rein = _FakeRein()
+    result = run_execution(_request(), catalog=_catalog_with_readiness(), rein=rein, manager=manager)
+    assert not result.ok
+    assert result.evidence.failure_stage == 'sandbox_create'
+    assert result.evidence.session_cleanup == 'not_attempted'
+    assert result.evidence.sandbox_destroy == 'succeeded'
+    assert rein.calls == []
+    manager.execute.assert_not_called()
+    manager.destroy.assert_called_once_with('sbx1')
+
+
+def test_reachability_preparation_failure_is_reported_and_destroyed():
+    manager = MagicMock()
+    reachability = MagicMock()
+    reachability.model_dump.side_effect = RuntimeError('private owner detail')
+    manager.create.return_value = _fake_status().model_copy(update={'reachability': reachability})
+    rein = _FakeRein()
+    with patch('glas_harness.gateway.hub.post_progress_event', return_value=True) as post:
+        result = run_execution(_request(report_to_hub=True), catalog=_catalog_with_readiness(),
+                               rein=rein, manager=manager)
+    assert not result.ok
+    assert result.evidence.failure_stage == 'session_start'
+    assert result.tool_error == 'private owner detail'
+    assert result.evidence.session_cleanup == 'not_attempted'
+    assert result.evidence.sandbox_destroy == 'succeeded'
+    assert 'private owner detail' not in str(post.call_args)
+    assert rein.calls == []
+    manager.destroy.assert_called_once_with('sbx1')