Ethereum's next fork changes 8 things every contract on the chain took for granted. The EF published the list and asked everyone to check their code before Glamsterdam ships: 1. Gas can now go up in the middle of a transaction. Until now it only went down. Any contract that measures "gas before minus gas after" to charge someone can get a negative number. 2. Prices jump 5 to 8 times for anything new. A new account: 25,000 gas becomes 183,600. A new storage slot: 22,100 becomes 110,020. Every hardcoded gas number in a contract, a bot or a signed message is now wrong. 3. The 2,300 gas that transfer() and send() give the recipient used to be enough for a tiny write. It is not anymore. Contracts receiving ETH that way can start failing. 4. A failed call used to leave too little gas to do anything after it. At new prices the leftover can be enough to record "done" for an item that never actually completed. 5. A call that fails now gives back the storage gas it spent. The caller has more gas than it expected, and code that guesses "it ran out of gas" from the gas left guesses wrong. 6. Running out of gas inside a call no longer kills the whole transaction. The code after it can still write storage and mark the failure as final. 7. Set a flag and clear it in the same transaction, and the gas refund arrives immediately instead of at the end. Reentrancy locks built this way behave differently. 8. A 7702 delegation that runs out of gas is rolled back, but the transaction is still mined and anyone can reuse the signature. The EF scanned every verified contract on Sourcify, found enough to delay the fork, and now asks you to point a coding agent at their repo with your own code. Billions in contracts nobody can change, running on a machine whose rules just did. What could go wrong.