%% api/shared_fence's lifetime check, step by step.
sequenceDiagram
    participant App
    participant Q as Compute queue
    participant V as FenceEvent (value)
    App->>V: CreateFence(SHARED), CreateSharedHandle
    App->>Q: Wait(fence, 1), then Signal(other, 2)
    App->>V: Release fence (handle still open)
    Note over Q,V: queue stays blocked: other == 1
    App->>V: OpenSharedHandle -> new fence, value 0
    App->>V: CloseHandle
    Note over Q,V: still blocked: a fence is alive
    App->>V: Release last fence -> sweep: our handle is the only one
    V-->>Q: value = max, wait released
    Q-->>App: other == 2