What

lockfree_spsc_queue in src/impl/async/lockfree_queue.h:191 declares a separate alignas(cache_line_size) std::array<std::atomic<size_t>, Size> sequence_ array. However, each cell struct (L:157) already contains its own std::atomic<size_t> sequence field. The standalone sequence_ array is initialized but never referenced in enqueue/dequeue operations.

Why

• With default Size = 1024, the unused array wastes ~8KB of memory
• The array also increases cache footprint, potentially evicting useful data from L1/L2 cache

Where

• src/impl/async/lockfree_queue.h:191 — unused sequence_ array declaration
• src/impl/async/lockfree_queue.h:157 — cell::sequence already provides per-slot sequencing

How

Acceptance Criteria

• sequence_ array removed
• Enqueue/dequeue logic verified to use cell::sequence exclusively
• All existing tests pass
• Memory footprint reduced by ~8KB per queue instance