Always add, never lose

Adding to cart never fails. Even if item soon becomes unavailable, cart entry stays. User sees it at checkout with 'unavailable' badge.

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Always add, never lose

Adding to cart never fails. Even if item soon becomes unavailable, cart entry stays. User sees it at checkout with 'unavailable' badge.

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Eventually consistent replicas

DynamoDB replicates cart. Reads may show stale. Adds converge. Removals resolved by vector clocks (concurrent add + remove → add wins).