fix sandbox create rollback gap

test/test_sandbox_usecase.py

@@ -669,6 +669,39 @@ def test_create_sandbox_error_records_observability(monkeypatch) -> None:
     assert excinfo.value in span.errors
 
 
+def test_create_sandbox_save_failure_stops_untracked_container(monkeypatch) -> None:
+    now = datetime(2026, 4, 2, 12, 0, tzinfo=UTC)
+    repository = FailingSaveRepository(RuntimeError('save_failed'))
+    repository.fail_next_save()
+    metrics = RecordingMetrics()
+    runtime = FakeRuntime()
+    usecase = CreateSandbox(
+        repository=repository,
+        locker=FakeLocker(),
+        runtime=runtime,
+        clock=FakeClock(now),
+        logger=FakeLogger(),
+        metrics=metrics,
+        tracer=NoopTracer(),
+        ttl=timedelta(minutes=5),
+    )
+    monkeypatch.setattr('usecase.sandbox._new_session_id', lambda: SESSION_NEW_ID)
+
+    with pytest.raises(RuntimeError, match='save_failed'):
+        usecase.execute(CreateSandboxCommand(chat_id=CHAT_ID))
+
+    assert len(runtime.create_calls) == 1
+    assert runtime.stop_calls == [f'container-{SESSION_NEW_ID}']
+    assert repository.get_active_by_chat_id(CHAT_ID) is None
+    assert _active_count_values(metrics)
+    assert _active_count_values(metrics)[-1] == 0
+    _assert_increment_metric_present(
+        metrics,
+        'sandbox.create.total',
+        attrs={'result': 'error'},
+    )
+
+
 def test_create_sandbox_replace_stop_failure_preserves_separate_identities(
     monkeypatch,
 ) -> None:
@@ -755,9 +788,11 @@ def test_create_sandbox_replace_save_failure_records_stage_safe_trace_ids(
     with pytest.raises(RuntimeError, match='save_failed') as excinfo:
         usecase.execute(CreateSandboxCommand(chat_id=CHAT_ID))
 
-    assert runtime.stop_calls == ['container-old']
+    assert runtime.stop_calls == ['container-old', f'container-{SESSION_NEW_ID}']
     assert len(runtime.create_calls) == 1
     assert repository.get_active_by_chat_id(CHAT_ID) is None
+    assert _active_count_values(metrics)
+    assert _active_count_values(metrics)[-1] == 0
     _assert_increment_metric_present(
         metrics,
         'sandbox.create.total',