Solana SIMD-0312 Fixes Sending SOL to Non-Existent Addresses

On Solana mainnet, the create_account_allow_prefund feature was activated on May 29, 2026, epoch 979, adding the CreateAccountAllowPrefund instruction. It allows creating an account at an address that already received SOL: the existing balance is counted, and the sender only pays the difference.

• Activated on mainnet May 29, 2026, epoch 979, slot 422,928,004
• Account order reversed from CreateAccount: new account index 0, payer index 1
• When requesting 0 lamports, only target account needed, no payer
• Does not work for token accounts and does not return SOL sent to wrong address