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How does automatic batching work in React 18, and how do you opt out?

Q: How does automatic batching work in React 18, and how do you opt out?

React 18 **automatically batches** every state update that happens in the same tick — including updates inside promises, `setTimeout`, and native event handlers — into a single re-render. (React 17 only batched updates originating inside React event handlers; updates in async callbacks each triggered their own render.) setA + setB + setC in one tick → ONE render setA <rect x="110" y="55" width="70" height="28" rx="6" fill="#3b

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