Solidity 0.8.36

Use these rules for Solidity 0.8.36 contracts, libraries, deployment scripts, upgrade systems, and off-chain integrations.

Contract authority

• Define every privileged role, capability, scope, transfer path, revocation path, and emergency action before coding.
• Authorize the exact state transition and target object instead of checking only msg.sender globally; never use tx.origin for authorization.
• Never rely on msg.sender == tx.origin, code.length == 0, or extcodesize to keep code-running callers out, block flash loans or sandwiches, or prevent reentrancy. Under EIP-7702 an EOA can run delegated code that calls your contract several times in one transaction with msg.sender == tx.origin; a delegated EOA also has nonzero code length, and a contract under construction has none.
• Use explicit role administration and avoid a single implicit owner where duties should be separated.
• Make ownership acceptance and role transfer two-step, for example with OpenZeppelin Ownable2Step or AccessControlDefaultAdminRules, when an incorrect recipient would be unrecoverable.
• Test that renounced, expired, paused, and removed authority cannot be recovered through alternate entry points.

External calls and reentrancy

• Apply checks, then effects, then interactions, and guard state that can be reentered with OpenZeppelin nonReentrant. Use ReentrancyGuardTransient on Cancun or newer chains, and the storage-based ReentrancyGuard, deprecated since OpenZeppelin 5.5, only where transient storage is unavailable.
• Treat calls to known tokens, libraries, hooks,